Psychosocial interventions for supporting women to stop smoking in pregnancy
Referencias
References to studies included in this review
References to studies excluded from this review
References to ongoing studies
Additional references
References to other published versions of this review
Characteristics of studies
Characteristics of included studies [ordered by study ID]
| Methods | 3‐armed randomised‐controlled trial (pilot study) evaluated 2 different interventions provided to 'pregnant teens' to reduce smoking in pregnancy and relapse postpartum. The hypothesis was that an intervention including peer support would be more effective than the intervention alone. Study conducted in Pittsburgh, USA. Data collection dates not reported. | |
| Participants | Inclusion criteria:12 to 20 years of age; 4 to 28 weeks' gestation; reported smoking at least 1 cigarette a day; single marital status; no previous live birth; able to read and write English. Baseline characteristics: Mean cigarettes/day at first visit: C = 6.44; I1 (TFS) = 5.87; I2 (TFSB) = 6.81. 63% African‐American heritage, 37% European‐American heritage. Progress + coding: Coded as single (low social capital) and young age (less than 20). | |
| Interventions | A: Control: 30 mins individual educational session with project nurse including information about the risks of smoking to the mother and the fetus and brochures on smoking and pregnancy. Main intervention strategy: Social support (multiple intervention) compared to less intensive intervention. TFSB (C) compared with TFS (B) and control (A) in this review as outcomes for A and B only reported as combined figures. Intensity rating: Frequency (C = 2, I = 6); Duration (C = 2, I = 6). Intervention provided by project staff:efficacy study. | |
| Outcomes | Biochemically validated point prevalence abstinence at 4‐6 weeks post baseline (late pregnancy*).Intervention arms B and C were combined so unable to report separately in this review. Reduction in exhaled CO and self‐reported mean cigarettes per day are reported as 'reduction' but actual post‐intervention measures were not reported so are not included in this review. Baseline modified Fagerstrom Tolerance questionnaire for adolescents to assess nicotine dependence. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as 'randomly assigned'. |
| Allocation concealment (selection bias) | Unclear risk | No information. |
| Incomplete outcome data (attrition bias) | Low risk | Only 46/84 had complete outcome data (high attrition rate = 45%), UC = 12 (41%), TFS = 13 (46%), TFSB = 13 (50%). No explanation for attrition. ITT analysis not mentioned. All those lost to follow‐up were included as continuing smokers in this review. |
| Selective reporting (reporting bias) | High risk | Only smoking outcomes reported and outcomes not reported separately for each of the control arms. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | CO level (>= 8 ppm) in exhaled air used to identify smokers. |
| Blinding of participants and personnel (performance bias) | High risk | Provider and participants unable to be blinded to educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Process evaluation showed there was a 'significant dropout rate' (45%). |
| Equal baseline characteristics in study arms | Unclear risk | Baseline smoking characteristics similar, but other baseline characteristics not reported. |
| Contamination of control group | Low risk | Intervention provided by research project staff. |
| Methods | 3‐armed randomised controlled trial evaluated the short‐ and long‐term effects of 2 smoking cessation strategies tailored to support pregnant adolescents to attain abstinence in pregnancy and maintain abstinence postpartum. The study was conducted in 5 hospital‐based and 2 community‐based prenatal clinics in Pittsburgh, Pennsylvania, USA. Years of data collection not reported. | |
| Participants | Inclusion criteria: 'Pregnant teens' aged 14 to 19 years; 12 to 28 weeks' gestation; able to read, write, and understand English; smoking at least 1 cigarette per day; single marital status; having no previous live births; and capable of being reached by telephone. Exclusion criteria: pregnancy complications (i.e. bleeding or preterm labor) or required confinement to home by their physician. Recruitment: During prenatal assessment, adolescents self‐reporting smoking were invited to participate in study. Those expressing interest signed a consent form to allow the research team to contact them. Expressions of interest also advertised through flyers and brochures. 470 screened; 142/224 (63%) eligible women randomised (C = 50; I1: (TFS) = 47; I2: (TFS + B) = 45. Fagerstrom dependence score: Control 3.38 (2.05); I1: (TFS) 3.44 (1.79); I2: (TFSB) 3.68 (1.89). Progress + coding: Low SES, Low educational attainment, low social capital (single) and young age (< 20 years). | |
| Interventions | A: Control: UC that all teens would typically receive from a healthcare provider throughout their pregnancy. Smoking during pregnancy was addressed in the clinic by giving the teens educational materials on this subject during the initial prenatal visit. In this study, this material was explained and distributed to the participants by a research team member during the initial assessment. The meetings lasted 45‐60 mins and occurred at 1 of the AN clinics or centrally located community site. During the meeting, addresses and telephone numbers of the control group participants were updated after completion of the assessment. Prior to leaving the meeting, participants were informed of the date and time of their next assessment. Participants also received an attendance incentive (e.g. lipstick, nail polish). If the participant had delivered, the attendance incentive was a baby item. B: Intervention 1 (TFS): The TFS intervention consisted of an 8‐week group program designed to promote and maintain smoking abstinence based on the Cognitive Behavioral Theory, with modification that incorporated developmental components of Jessor’s Problem Behavior Theory, including a peer buddy and a peer co‐leader for peer modelling and sanctioning on smoking. Information pertinent to pregnancy and smoking was provided at the beginning of the 8‐week program. Main intervention strategy: Social support (multiple intervention) compared to a less intensive intervention. The control group and TFS‐B are compared in Albrecht 2006 (AvC) Intensity rating: Frequency (C = 2, I = 6); Duration (C = 3, I = 6). Provided by dedicated project staff: efficacy study. | |
| Outcomes | Biochemically validated point prevalence abstinence 8 weeks (late pregnancy*) and 1 year (6‐11 months post partum*) after the intervention. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Consenting adolescents were assigned randomly to 1 of 3 group assignments (TFS, TFS‐B, or control) by a computer algorithm with a permutated block design, stratified by entry site. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | High attrition: C = 60% (i.e. 40% did not complete 1 yr follow‐up), TFS = 55%, TFS‐B = 53%. Participants included in primary aim analysis pertaining to randomised treatment assignment, regardless of adherence to study treatment (ITT analysis). |
| Selective reporting (reporting bias) | Low risk | Primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation of self‐reported smoking status (point prevalence abstinence) using salivary cotinine (> 10 ng). Women reporting less than 1 cigarette per day with salivary cotinine 10‐15 ng had salivary nicotine assessment to rule out environmental exposure, and were classified as smokers if that test was > 5 ng. |
| Blinding of participants and personnel (performance bias) | High risk | Participants and providers unlikely to be blinded to this educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Blinding of outcome assessor not reported. |
| Incomplete implementation | High risk | Process evaluation showed poor implementation with almost 50% participants not completing study. |
| Equal baseline characteristics in study arms | Low risk | Baseline characteristics appear equal. |
| Contamination of control group | Low risk | Intervention provided by research team. |
| Methods | 3‐armed randomised controlled trial evaluated the short‐ and long‐term effects of 2 smoking cessation strategies tailored to support pregnant adolescents to attain abstinence in pregnancy and maintain abstinence postpartum. The study was conducted in 5 hospital‐based and 2 community‐based prenatal clinics in Pittsburgh, Pennsylvania, USA. Years of data collection not reported. | |
| Participants | Inclusion criteria: 'Pregnant teens' aged 14 to 19 years; 12 to 28 weeks' gestation; able to read, write, and understand English; smoking at least 1 cigarette per day; single marital status; having no previous live births; and capable of being reached by telephone. Exclusion criteria: pregnancy complications (i.e. bleeding or preterm labor) or required confinement to home by their physician. Recruitment: During prenatal assessment, adolescents self‐reporting smoking were invited to participate in study. Those expressing interest signed a consent form to allow the research team to contact them. Expressions of interest also advertised through flyers and brochures. 470 screened; 142/224 (63%) eligible women randomised (C = 50; I1: (TFS) = 47; I2: (TFS + B) = 45. Fagerstrom dependence score: Control 3.38 (2.05); I1: (TFS) 3.44 (1.79); I2: (TFSB) 3.68 (1.89). Progress + coding: Low SES, Low educational attainment, low social capital (single) and young age (< 20 years). | |
| Interventions | A: Control: UC that all teens would typically receive from a healthcare provider throughout their pregnancy. Smoking during pregnancy was addressed in the clinic by giving the teens educational materials on this subject during the initial prenatal visit. In this study, this material was explained and distributed to the participants by a research team member during the initial assessment. The meetings lasted 45‐60 mins and occurred at 1 of the AN clinics or centrally located community site. During the meeting, addresses and telephone numbers of the control group participants were updated after completion of the assessment. Prior to leaving the meeting, participants were informed of the date and time of their next assessment. Participants also received an attendance incentive (e.g. lipstick, nail polish). If the participant had delivered, the attendance incentive was a baby item. B: Intervention 1 (TFS): The TFS intervention consisted of an 8‐week group program designed to promote and maintain smoking abstinence based on the Cognitive Behavioral Theory, with modification that incorporated developmental components of Jessor’s Problem Behavior Theory, including a peer buddy and a peer co‐leader for peer modelling and sanctioning on smoking. Information pertinent to pregnancy and smoking was provided at the beginning of the 8‐week program. Main intervention strategy: Social support (multiple intervention) compared to a less intensive intervention. The control group and TFS are compared in Albrecht 2006 (AvB). Intensity rating: Frequency (C = 2, I = 6); Duration (C = 3, I = 6). Provided by dedicated project staff: efficacy study. | |
| Outcomes | Biochemically validated 24‐hr point prevalence abstinence 8 weeks (late pregnancy*) and 1 year (6‐11 months post partum*) after the intervention. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Consenting adolescents were assigned randomly to 1 of 3 group assignments (TFS, TFS‐B, or control) by a computer algorithm with a permutated block design, stratified by entry site. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | High attrition: C = 60% (i.e. 40% did not complete 1 yr follow‐up), TFS = 55%, TFS‐B = 53%. Participants included in primary aim analysis pertaining to randomised treatment assignment, regardless of adherence to study treatment (ITT analysis). |
| Selective reporting (reporting bias) | Low risk | Primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation of self‐reported smoking status (point prevalence abstinence) using salivary cotinine (> 10 ng). Women reporting less than 1 cigarette per day with salivary cotinine 10‐15 ng had salivary nicotine assessment to rule out environmental exposure, and were classified as smokers if that test was > 5 ng. |
| Blinding of participants and personnel (performance bias) | High risk | Participants and providers unlikely to be blinded to this educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Blinding of outcome assessor not reported. |
| Incomplete implementation | High risk | Process evaluation showed poor implementation with almost 50% participants not completing study. |
| Equal baseline characteristics in study arms | Low risk | Baseline characteristics appear equal. |
| Contamination of control group | Low risk | Intervention provided by research team. |
| Methods | A 2‐arm randomised controlled pilot study to evaluate whether medical advice had a effect on smoking cessation in pregnancy. Study conducted in Bolton, England. Years of data collection not reported. | |
| Participants | Inclusion criteria: Pregnant smokers at their first AN visit, less than 20 weeks' gestation. Exclusion criteria: Not reported. Recruitment: Women recruited from public AN clinic at Bolton and District General Hospital. 510 women screened, 142 eligible, 8 moved house and could not be followed up, and 24 women had spontaneously quit. 110 women randomised: control = 47, intervention = 63. Baseline characteristics: 89% heavy smokers and 75% had been smoking for 5 years or more. 72% 'working‐class' (majority low SES) and 75% had no educational qualifications. Progress + coding: Low SES and low educational attainment. | |
| Interventions | Control: UC, which was advice at the discretion of the doctor. Main intervention strategy: Counselling (single intervention) compared with UC. Intensity: Frequency (C = 0, I = 1); Duration: (C = 0, I = 1). UC intensity: Frequency = 1, duration = 1. | |
| Outcomes | Self‐reported abstinence 11 weeks after baseline visit (late pregnancy*). Smoking reduction reported for whole cohort, not by intervention group, therefore not included in this review. Discusses participants' views of intervention. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | No information provided. Described as "randomly divided". |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | Low risk | There are some missing data in the tables. It is not clear if there was any overall loss to follow‐up or whether missing data relate to specific outcomes only. All randomised women included in this review and those lost to follow‐up were included as continuing smokers in this review. |
| Selective reporting (reporting bias) | Unclear risk | No other outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Smoking outcomes were self‐reported by participants during a visit at home. There was no biochemical validation. |
| Blinding of participants and personnel (performance bias) | High risk | Educational intervention at first AN visit. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Not reported. |
| Equal baseline characteristics in study arms | Unclear risk | Not reported. |
| Contamination of control group | Low risk | Medical student provided intervention (not UC provider). |
| Methods | Randomised controlled trial of use of exhaled CO feedback for promoting smoking cessation in pregnancy. Study conducted in Guildford County, North Carolina, USA over 6 months in 1981. | |
| Participants | Inclusion criteria: Women currently or recently smoking, attending public clinics. Exclusion criteria: Not reported. All women attending AN care‐orientation sessions were randomly allocated to experimental or control groups. Recruitment: 226 women entered prenatal program and 170 (75%) included in analyses. The authors compared those who did not participate and did not find any significant differences. 47% (79/170) were current smokers (C = 43, I = 36). Baseline characteristics: 43% had completed high school education, 56% were black, 80% classified as having no pregnancy risks other than smoking. 38% in the first trimester and 46% in the second trimester of pregnancy. Progress + coding: Low SES as all attending public prenatal clinic. | |
| Interventions | Control: Women were read a 135 script that described the relationship among cigarette smoking, CO, and the harmful consequences of smoking. Intervention: Experimental group received same information as control group, and they provided breath specimen in which CO was measured, with feedback of the result. Main intervention strategy: Feedback (single intervention) compared to a less intensive intervention. Intensity: Frequency (C = 1, I = 1); Duration (C = 1, I = 1). Implemented by regular health educators: effectiveness study. | |
| Outcomes | Biochemically validated abstinence 6 weeks after intervention (late pregnancy*). Exhaled CO (ppm), but no SD reported; unclear if 'quantity of cigarettes' is mean cigarettes per day; how recent was smoking; depth of inhalation. | |
| Notes | Not clear whether this was a group intervention ‐ in which case there was no adjustment for clustering. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Random number table. |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | Unclear risk | Unclear exactly how many women were randomised to each group, however we assume that those reported as 'current smokers' in table 1 are the baseline numbers, which were all included in this review. |
| Selective reporting (reporting bias) | Unclear risk | None apparent. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation of reported smoking behaviour for those followed up (CO >= 9 ppm in exhaled air). |
| Blinding of participants and personnel (performance bias) | High risk | Intervention was carried out by clinical staff, no participant blinding reported. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | All women apparently received the intervention. |
| Equal baseline characteristics in study arms | Low risk | No difference between experimental and control arms on 12 variables measured. |
| Contamination of control group | Low risk | Implemented by regular health educators at the maternity clinics. |
| Methods | Randomised controlled trial of psychosocial support in pregnancy which aimed to improve maternal health, including reducing smoking during pregnancy. Conducted in 4 countries in Latin America (Argentina, Brazil, Cuba, and Mexico) from January 1989 to March 1991. | |
| Participants | Inclusion criteria:High‐risk women whose AN care began at 15‐22 weeks' gestation, singleton pregnancy, 1 or more of the following: prior LBW infant; preterm birth; perinatal/infant death; < 18 years; body weight <= 50 kg; height <= 150 cm; low family income (local definitions applied); < 3 years school; crowded household (4 or more persons/bedroom); smoking; not living with husband or partner. Recruitment: 2235 women met eligibility criteria and gave consent (I = 1115‐though 1110 in table, C = 1120). Baseline characteristics: Smokers (I = 23.9%, C = 21.8%), with variation between countries ‐ Argentina (I = 21.9%, C = 20.6%), Brazil (I = 40.7%, C = 33.1%), Cuba (I = 27.4%, C = 28.9%), Mexico (I = 9%, C = 6.8%). Mean cigarettes per day at randomisation: C = 7.9, I = 7.5. Progress + coding: Low SES based on place of residence (low family income 20% in Cuba, 52% in Mexico, 53% in Brazil and 100% in Argentina). | |
| Interventions | Control: Routine AN care, otherwise unspecified. Intervention: Flexible use of a standardised manual, based on site‐specific ethnographic studies of needs, fears, expectations, social support networks, including detailed descriptions of situations likely to occur during home visits. 4 to 6 home visits of 1 to 2 hours with emphasis on psychosocial support, education on health habits including better nutrition, reducing smoking alcohol and other drugs, reducing their physical workload, recognition of alarm signs and symptoms, improved access to hospital facilities, reinforcement of health service utilisation. Additional components were a poster, a booklet, hotline to project office, guided tour of hospital, encouragement of family support and participation. Intervention was provided by specially trained female social workers or obstetric nurses with previous experience of childbirth. Main intervention strategy: Maternal health intervention with smoking component: social support (tailored) compared with UC. Intensity: Frequency (C = 0, I = 6), Duration (C = 0, I = 5). UC frequency and duration = 0 (unclear). Intervention provided by study team: efficacy study. | |
| Outcomes | Self‐reported point prevalence abstinence at 36 weeks' gestation (late pregnancy*); Mean cigarettes per day.* Multiple perinatal and maternal health outcome data were collected, but not included in this review as other aspects of the intervention may have had an impact. Baseline state anxiety score and associations with other factors. | |
| Notes | Sample size was planned for the primary trial objective. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Centrally prepared, method not stated. |
| Allocation concealment (selection bias) | Low risk | Allocation was by opening sealed, opaque envelopes. |
| Incomplete outcome data (attrition bias) | High risk | Attrition 202/2230 (9%): 101 in each arm. Unclear what attrition among smokers and no ITT analysis of dropouts as continuing smokers, so not able to re‐include smokers who dropped out in this review. |
| Selective reporting (reporting bias) | Unclear risk | None apparent. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | No biochemical validation of reported smoking behaviour. |
| Blinding of participants and personnel (performance bias) | High risk | Home visitors were aware of group allocation. Social support intervention with home visits. |
| Blinding of outcome assessment (detection bias) | Low risk | The evaluation of the interventions was conducted by a team of independent professional interviewers who were not informed of the characteristics of the study. |
| Incomplete implementation | Low risk | Most (83%) of the women randomly assigned to the intervention group received the planned number of home visits, and 90% were visited at least once. |
| Equal baseline characteristics in study arms | Low risk | The distribution of risk factors was similar in the 2 groups and the 2 groups had similar demographic, obstetric, and psychological characteristics at baseline. |
| Contamination of control group | Low risk | The clinic personnel were unaware of the identity of the women in the control group, and no attempts were made to inform them of which women were in the intervention group. Health educators providing intervention were separate from care providers. |
| Methods | 2‐armed randomised controlled trial of telephone support for improving maternal health outcomes, including smoking cessation during pregnancy. Study conducted in a metropolitan city in the south island of New Zealand from March to December 1993. | |
| Participants | Inclusion criteria: Women with telephone access, who were either single or with an unemployed partner, less than 20 weeks' gestation. Exclusion criteria: None stated. Recruitment: Recruited in the outpatient department of a large maternity hospital, or its associated GP practices, or self‐referral via an introductory letter, phone call, and full discussion of "Healthy Mothers/Healthy Babies". The eligible population was 221 women of whom 49 were never located, 23 were not interested, 10 refused after explanation, and 8 moved away, did not speak English or had a miscarriage. 131 (59%) participated (103 OPD, 22 from GPs, 6 self‐referred) (C = 66, I = 65 randomised). Just over 50% were smokers (C = 35, I = 31). 88% European, 10% Maori. 53% single. Progress + coding: Low SES. | |
| Interventions | Control: Package of publicly available educational material on healthy behaviours during pregnancy. Main intervention strategy: Maternal health intervention with smoking component: Social support (single intervention) compared to a less intensive intervention. Intensity: Frequency (C = 2, I = 6); Duration (C = 1, I = 4). Intervention provided by project staff: efficacy study. | |
| Outcomes | Self‐reported abstinence at 34/40 (late pregnancy*). Mean cigarettes per day*. Anxiety (Speilbergers State anxiety score) and depression (Levine Pilowsky Depression inventory) at baseline and 34/40; stress; social support; self‐esteem. There were other intervention components which might have influenced these outcomes. | |
| Notes | No process evaluation is reported. No sample size justification. SDs for mean cigarettes per day were not reported, therefore we calculated a mean SD from 14 studies with available mean cigarette SDs (6.5) to include in this review, as recommended by the cochrane handbook. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer‐generated random assignment to control or intervention in balanced blocks of 50. |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | High risk | Data being reported were analysed on 122/131 of randomised women (control = 63/66, intervention = 59/65). 1 woman requested to be removed from the study, but there were 8 women who for various reasons had incomplete data. p477 4.5% control 9.2% intervention. Only a proportion were smokers (I = 31, C = 35), and the attrition among these is not reported so we were unable to re‐include them in the analysis for this review. |
| Selective reporting (reporting bias) | Unclear risk | None apparent. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | No biochemical validation of reported smoking behaviour. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Caregiver blinded to allocation. Women not blinded to intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | No process evaluation. |
| Equal baseline characteristics in study arms | Unclear risk | Baseline psychosocial variables (stress; social support; self‐esteem; depression; anxiety) reported in Table 2. Demographic variables not reported. |
| Contamination of control group | Unclear risk | Care providers blinded to allocation and not involved in intervention delivery. |
| Methods | Randomised controlled trial (2 x 2 factorial design) evaluating nurse delivered telephone social support (‘‘Baby BEEP’’) to improve a range of maternal health outcomes, including smoking during pregnancy. | |
| Participants | Inclusion criteria: Women attending rural WIC clinic who reported smoking at least 1 cigarette per day, spoke English, were 18 years or older, and less than 24 weeks' gestation. Exclusion criteria: Not further specified. Recruitment: When a woman attending a WIC clinic reported current smoking, staff explained the availability of a smoking cessation study and asked permission to provide her name and telephone number to the Baby BEEP research team. If the woman agreed, a nurse from the research team was assigned to contact her to arrange a face‐to‐face visit to explain the study and request written consent. 1420 referrals from WIC clinics, 932 eligible, 695 (75%) randomised (C = 171; I1 (booklets) = 179; I2 (social support) = 175, I3 (social support + booklets) = 170. Baseline characteristics: > 90% 'ready to quit this pregnancy'. Fagerstrom scores: C = 4.8, I1 (Booklets) = 5.0, I2 (SS) = 4.9, I3 (SS + booklets) = 4.7 Mean age: 22 years, 95% white, 63% high school diploma, 70% in relationship. Psychosocial assessments indicated participants experienced high levels of perceived stress and depression and low levels of support generally and from partners. Progress + coding: Low SES as women recruited from WIC clinics. | |
| Interventions | A: Control: Quit Smoking for Good pamphlet from the American Heart Association and instructed that a member of the research team would call each month to arrange a saliva sample, measure exposure to tobacco smoke and ask some questions for 2 more interviews. Intervention (3 arms): B: I1 Serialised Pregnancy‐Smoking Cessation Booklets (Booklets):Eight booklets comprised a program called ‘‘Stop Smoking! A Special Program for Pregnant Women’’ adapted to a 7th grade reading level. The first booklet was given to the woman at the recruitment visit without counselling, and the 7 remaining booklets were mailed at weekly intervals. C: I2 Nurse‐Delivered General Social Support (SS): scheduled weekly telephone call and 24‐hour access to the nurse for any additional social support needed. The research nurse’s role on the calls was to use empathetic listening skills and provide social, emotional and/or informational support in response to each woman’s individual needs, such as stressors she was facing and ways she could manage her stress responses. The nurses kept logs of all conversations so that they would be able to follow‐up on issues of importance on subsequent calls and as a measure of treatment integrity. D: I3 SS + Booklets: This study ID included comparisons arms A + C v B + D to utilise the factorial design to assess impact of booklets and arm B (Booklets). Main intervention strategy: Maternal health intervention with smoking component: Health education(single) compared to a less intensive intervention. Intensity: Frequency (C = 1, I = 2); Duration (C = 1, I = 1). Intervention provided by project staff: Efficacy study. | |
| Outcomes | Biochemically validated point prevalence abstinence at 28‐32 weeks' gestation* (late pregnancy) and 6 weeks post‐delivery (0‐5 months postpartum*). Baseline perceived stress scale, prenatal psychosocial profile, mental health index 5; readiness to stop smoking; Fagerstrom Test for Nicotine Dependence. Subgroup analysis for patterns of quitting and associations with partner smoking. | |
| Notes | Process evaluation to follow‐up phone calls. Low attrition rate suggested as indicator of acceptability. The sample size of the control group is split in comparison 'all interventions vs all controls' to avoid double counting of participants in analysis. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Assignments were prepared individually for each nurse, were computer generated using SAS |
| Allocation concealment (selection bias) | Low risk | Opaque, sealed envelope, prepared by the principle investigator that contained the study group assignment. |
| Incomplete outcome data (attrition bias) | High risk | Attrition: 9 had a spontaneous abortion (C = 2, I1 = 3, I2 = 3, I3 = 1) or non‐viable infant (C = 0, I1 = 4,I2 = 1, I3 = 4) and were excluded from the analysis in this review. Those who dropped out and were lost to follow‐up for other reasons were included in the final analysis as continuing smokers (C = 7, I1 = 11, I2 = 11, I3 = 7). However, 165 women were lost to lab error in analysing their saliva samples and were not included in analysis. Only 530/695 (76%) randomised participants were included in this analysis. C = 128, I1 = 141, I2 = 132, I3 = 129 (n = 530) included as denominators in this review. |
| Selective reporting (reporting bias) | Low risk | All primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | 165/695 sample lost. Self‐reported abstinence in remaining women biochemically validated using salivary cotinine (30 ng/mL or less classified as non‐smokers). |
| Blinding of participants and personnel (performance bias) | High risk | The nurses who collected samples when they conducted the follow‐up interviews in late pregnancy and 6‐weeks postdelivery were aware of the study group assignment. |
| Blinding of outcome assessment (detection bias) | Low risk | The laboratory was blind to study group assignment while running the cotinine analyses. The assistants who collected the monthly saliva sample may or may not have been blinded to the study group but the rule was to treat all the women the same way. |
| Incomplete implementation | High risk | Percentage of calls completed in each of their caseloads ranged from 58% to 80% (p400). |
| Equal baseline characteristics in study arms | Low risk | Characteristics appear equal. |
| Contamination of control group | Low risk | Care‐providers not involved in provision of the intervention. |
| Methods | Randomised controlled trial (2 x 2 factorial design) evaluating nurse delivered telephone social support (‘‘Baby BEEP’’) to improve a range of maternal health outcomes, including smoking during pregnancy. | |
| Participants | Inclusion criteria: Women attending rural WIC clinic who reported smoking at least 1 cigarette per day, spoke English, were 18 years or older, and less than 24 weeks' gestation. Exclusion criteria: Not further specified. Recruitment: When a woman attending a WIC clinic reported current smoking, staff explained the availability of a smoking cessation study and asked permission to provide her name and telephone number to the Baby BEEP research team. If the woman agreed, a nurse from the research team was assigned to contact her to arrange a face‐to‐face visit to explain the study and request written consent. 1420 referrals from WIC clinics, 932 eligible, 695 (75%) randomised (C = 171; I1 (booklets) = 179; I2 (social support) = 175, I3 (social support + booklets) = 170. Baseline characteristics: > 90% 'ready to quit this pregnancy'. Fagerstrom scores: C = 4.8, I1 (Booklets) = 5.0, I2 (SS) = 4.9, I3 (SS + booklets) = 4.7 Mean age: 22 years, 95% white, 63% high school diploma, 70% in relationship. Psychosocial assessments indicated participants experienced high levels of perceived stress and depression and low levels of support generally and from partners. Progress + coding: Low SES as women recruited from WIC clinics. | |
| Interventions | A: Control: Quit Smoking for Good pamphlet from the American Heart Association and instructed that a member of the research team would call each month to arrange a saliva sample, measure exposure to tobacco smoke and ask some questions for 2 more interviews. Intervention (3 arms): B: I1 Serialised Pregnancy‐Smoking Cessation Booklets (Booklets):Eight booklets comprised a program called ‘‘Stop Smoking! A Special Program for Pregnant Women’’ adapted to a 7th grade reading level. The first booklet was given to the woman at the recruitment visit without counselling, and the 7 remaining booklets were mailed at weekly intervals. C: I2 Nurse‐Delivered General Social Support (SS): scheduled weekly telephone call and 24‐hour access to the nurse for any additional social support needed. The research nurse’s role on the calls was to use empathetic listening skills and provide social, emotional and/or informational support in response to each woman’s individual needs, such as stressors she was facing and ways she could manage her stress responses. The nurses kept logs of all conversations so that they would be able to follow‐up on issues of importance on subsequent calls and as a measure of treatment integrity. D: I3 SS + Booklets: This study ID included comparisons with the control group and arm C (SS). Main intervention strategy: Maternal health intervention with smoking component: Social support (single) compared to a less intensive intervention. Intensity: Frequency (C = 1, I = 6); Duration (C = 1, I = 4). Intervention provided by project staff: Efficacy study. | |
| Outcomes | Biochemically validated point prevalence abstinence at 28‐32 weeks' gestation* (late pregnancy) and 6 weeks post‐delivery (0‐5 months postpartum*). Baseline perceived stress scale, prenatal psychosocial profile, mental health index 5; readiness to stop smoking; Fagerstrom Test for Nicotine Dependence. Subgroup analysis for patterns of quitting and associations with partner smoking. | |
| Notes | Process evaluation to follow‐up phone calls. Low attrition rate suggested as indicator of acceptability. The sample size of the control group is split in comparison 'all interventions vs all controls' to avoid double counting of participants in analysis. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Assignments were prepared individually for each nurse, were computer generated using SAS. |
| Allocation concealment (selection bias) | Low risk | Opaque, sealed envelope, prepared by the principle investigator that contained the study group assignment. |
| Incomplete outcome data (attrition bias) | High risk | Attrition: 9 had a spontaneous abortion (C = 2, I1 = 3, I2 = 3, I3 = 1) or non‐viable infant (C = 0, I1 = 4,I2 = 1, I3 = 4) and were excluded from the analysis in this review. Those who dropped out and were lost to follow‐up for other reasons were included in the final analysis as continuing smokers (C = 7, I1 = 11, I2 = 11, I3 = 7). However, 165 women were lost to lab error in analysing their saliva samples and were not included in analysis. Only 530/695 (76%) randomised participants were included in this analysis. C = 128, I1 = 141, I2 = 132, I3 = 129 (n = 530) included as denominators in this review. |
| Selective reporting (reporting bias) | Low risk | All primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | 165/695 sample lost. Self‐reported abstinence in remaining women biochemically validated using salivary cotinine (30 ng/mL or less classified as non‐smokers). |
| Blinding of participants and personnel (performance bias) | High risk | The nurses who collected samples when they conducted the follow‐up interviews in late pregnancy and 6‐weeks postdelivery were aware of the study group assignment. |
| Blinding of outcome assessment (detection bias) | Low risk | The laboratory was blind to study group assignment while running the cotinine analyses. The assistants who collected the monthly saliva sample may or may not have been blinded to the study group but the rule was to treat all the women the same way. |
| Incomplete implementation | High risk | Percentage of calls completed in each of their caseloads ranged from 58% to 80% (p400). |
| Equal baseline characteristics in study arms | Low risk | Characteristics appear equal. |
| Contamination of control group | Low risk | Care‐providers not involved in provision of the intervention. |
| Methods | Randomised controlled trial (2 x 2 factorial design) evaluating nurse delivered telephone social support (‘‘Baby BEEP’’) to improve a range of maternal health outcomes, including smoking during pregnancy. | |
| Participants | Inclusion criteria: Women attending rural WIC clinic who reported smoking at least 1 cigarette per day, spoke English, were 18 years or older, and less than 24 weeks' gestation. Exclusion criteria: Not further specified. Recruitment: When a woman attending a WIC clinic reported current smoking, staff explained the availability of a smoking cessation study and asked permission to provide her name and telephone number to the Baby BEEP research team. If the woman agreed, a nurse from the research team was assigned to contact her to arrange a face‐to‐face visit to explain the study and request written consent. 1420 referrals from WIC clinics, 932 eligible, 695 (75%) randomised (C = 171; I1 (booklets) = 179; I2 (social support) = 175, I3 (social support + booklets) = 170. Baseline characteristics: > 90% 'ready to quit this pregnancy'. Fagerstrom scores: C = 4.8, I1 (Booklets) = 5.0, I2 (SS) = 4.9, I3 (SS + booklets) = 4.7 Mean age: 22 years, 95% white, 63% high school diploma, 70% in relationship. Psychosocial assessments indicated participants experienced high levels of perceived stress and depression and low levels of support generally and from partners. Progress + coding: Low SES as women recruited from WIC clinics. | |
| Interventions | A: Control: Quit Smoking for Good pamphlet from the American Heart Association and instructed that a member of the research team would call each month to arrange a saliva sample, measure exposure to tobacco smoke and ask some questions for 2 more interviews. Intervention (3 arms): B: I1 Serialised Pregnancy‐Smoking Cessation Booklets (Booklets):Eight booklets comprised a program called ‘‘Stop Smoking! A Special Program for Pregnant Women’’ adapted to a 7th grade reading level. The first booklet was given to the woman at the recruitment visit without counselling, and the 7 remaining booklets were mailed at weekly intervals. C: I2 Nurse‐Delivered General Social Support (SS): scheduled weekly telephone call and 24‐hour access to the nurse for any additional social support needed. The research nurse’s role on the calls was to use empathetic listening skills and provide social, emotional and/or informational support in response to each woman’s individual needs, such as stressors she was facing and ways she could manage her stress responses. The nurses kept logs of all conversations so that they would be able to follow‐up on issues of importance on subsequent calls and as a measure of treatment integrity. D: I3 SS + Booklets: This study ID included comparisons with the control group and arm D(I3) (SS + Booklets). Main intervention strategy: Maternal health intervention with smoking component: Social support (multiple) compared to a less intensive intervention. Intensity: Frequency (C = 1, I = 6); Duration (C = 1, I = 4). Intervention provided by project staff: Efficacy study. | |
| Outcomes | Biochemically validated point prevalence abstinence at 28‐32 weeks' gestation* (late pregnancy) and 6 weeks post‐delivery (0‐5 months postpartum*). Baseline perceived stress scale, prenatal psychosocial profile, mental health index 5; readiness to stop smoking; Fagerstrom Test for Nicotine Dependence. Subgroup analysis for patterns of quitting and associations with partner smoking. | |
| Notes | Process evaluation to follow‐up phone calls. Low attrition rate suggested as indicator of acceptability. The sample size of the control group is split in comparison 'all interventions vs all controls' to avoid double counting of participants in analysis. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Assignments were prepared individually for each nurse, were computer generated using SAS |
| Allocation concealment (selection bias) | Low risk | Opaque, sealed envelope, prepared by the principle investigator that contained the study group assignment. |
| Incomplete outcome data (attrition bias) | High risk | Attrition: 9 had a spontaneous abortion (C = 2, I1 = 3, I2 = 3, I3 = 1) or non‐viable infant (C = 0, I1 = 4,I2 = 1, I3 = 4) and were excluded from the analysis in this review. Those who dropped out and were lost to follow‐up for other reasons were included in the final analysis as continuing smokers (C = 7, I1 = 11, I2 = 11, I3 = 7). However, 165 women were lost to lab error in analysing their saliva samples and were not included in analysis. Only 530/695 (76%) randomised participants were included in this analysis. C = 128, I1 = 141, I2 = 132, I3 = 129 (n = 530) included as denominators in this review. |
| Selective reporting (reporting bias) | Low risk | All primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | 165/695 sample lost. Self‐reported abstinence in remaining women biochemically validated using salivary cotinine (30 ng/mL or less classified as non‐smokers). |
| Blinding of participants and personnel (performance bias) | High risk | The nurses who collected samples when they conducted the follow‐up interviews in late pregnancy and 6‐weeks postdelivery were aware of the study group assignment. |
| Blinding of outcome assessment (detection bias) | Low risk | The laboratory was blind to study group assignment while running the cotinine analyses. The assistants who collected the monthly saliva sample may or may not have been blinded to the study group but the rule was to treat all the women the same way. |
| Incomplete implementation | High risk | Percentage of calls completed in each of their caseloads ranged from 58% to 80% (p400). |
| Equal baseline characteristics in study arms | Low risk | Characteristics appear equal. |
| Contamination of control group | Low risk | Care‐providers not involved in provision of the intervention. |
| Methods | Randomised controlled trial of CO feedback and brief directive feedback to reduce smoking in pregnancy. Study conducted in a large USA municipal hospital AN clinic, over an 18‐month study period (dates not specified). | |
| Participants | Inclusion criteria: Pregnant women, currently smoking, at any gestation, attending a clinic for 'uncomplicated pregnancies'. Exclusion criteria: Very young age (not specified) or "complications" (not specified). Recruitment: All attending women were screened for smoking by questionnaire + CO breath measurement (>= 9 ppm) (over 50% were current smokers) and 139 women were randomly assigned (C = 69, I = 70). Baseline characteristics: An average of 12.7 cigarettes per day. The population consisted primarily poor and stable 'working class' Caucasian women (52.4%), Black (44.6%) and Asian (3%). Progress + coding: Low SES. | |
| Interventions | Control: UC, where a clinic nurse provided health education, including risks of smoking. Main intervention strategy: Health education (single intervention) compared to UC. CO feedback was provided to both groups so not included as a feedback trial. Intensity: Frequency (C = 0, I = 1), Duration (C = 0, I = 1). UC intensity: Frequency = 1, Duration = 1. Intervention provided by routine clinic staff: Effectiveness study. | |
| Outcomes | Biochemically validated point prevalence smoking cessation at 34 weeks' gestation (late pregnancy*). Number of cigarettes per day and CO levels collected but not reported. | |
| Notes | Simple intervention so no process evaluation. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | No information provided. |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | Low risk | No consent sought and no loss to follow‐up apparent. |
| Selective reporting (reporting bias) | Unclear risk | None apparent. Primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation of reported behaviour by exhaled CO (>= 9 ppm counted as smoking). |
| Blinding of participants and personnel (performance bias) | Unclear risk | The authors state that clinic staff were unaware of group allocation. Women would not have been blind to educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | All intervention participants provided with letter. No information regarding whether they read it or not. |
| Equal baseline characteristics in study arms | Unclear risk | There were no significant baseline differences between 2 groups in terms of age, ethnicity, term of pregnancy, number of children, number of reported cigarettes smoked, or CO. |
| Contamination of control group | Low risk | Intervention was a letter so unlikely to be sent to control group in error. |
| Methods | This 2‐armed randomised controlled study aimed to evaluate the effectiveness of nurse counselling to reduce smoking in pregnancy. The study was conducted in 2 community‐based obstetric clinics in Milwaukee (USA). Study dates unclear. | |
| Participants | Inclusion criteria: Pregnant, ‘a current smoker’, English speaking, visually able to read 12 point typeset, being able to give free consent, and expecting to reside in Milwaukee following delivery. Exclusion criteria: Not specified. Recruitment: 50% of patients enrolled in third trimester. 57 women randomised, but unclear how many to each group. Baseline characteristics: Cigarette consumption mean at entry = 8.6 93% participants smoked fewer than 10 cigarettes per day. 79% Black participants, 16% had partner, 70% single, 77% unemployed, 32% < grade 12 education, 61% < $10,000 per year. No coding as outcomes not able to be included in this review. | |
| Interventions | Control: A smoking cessation booklet at 6th grade reading level or 11 min videotape. Intervention: Booklet or video Nurse counselling based on 4 As recommended by National Cancer Institute. The nurse intervention was a systematic tailored smoking cessation approach that was based on the 4 A (Ask, Advise, Assist, Arrange) approach by the National Cancer Institute. Main intervention strategy and intensity not coded as not included in meta‐analysis. | |
| Outcomes | Self‐reported smoking status (20% had CO screening) 1 month after enrolment, in the ninth month of pregnancy, and 1 month postpartum. But not reported by intervention group so unable to include any outcomes in meta‐analysis. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Method of sequence generation not stated. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | Of the 57 participants enrolled in the study, 50 were available for 1‐ and 9‐month follow‐up, and 48 responded to the 1‐month postpartum survey. All non‐respondents were considered to be smokers at follow‐up and considered to have made no quit attempts in the follow‐up interval. |
| Selective reporting (reporting bias) | Unclear risk | Outcomes not reported by intervention group, but did not claim results were significant. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Self‐reported smoking status for 80% sample. |
| Blinding of participants and personnel (performance bias) | High risk | Participants and personal unlikely to be blinded in educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Not reported. |
| Equal baseline characteristics in study arms | Unclear risk | Not reported. |
| Contamination of control group | Low risk | Home visits. |
| Methods | Cluster‐randomised controlled trial which aimed to assess 2 methods of disseminating smoking cessation programmes to public AN clinics. Study conducted in Newcastle, New South Wales, Australia. Data collection dates not reported. | |
| Participants | Inclusion criteria: Public AN clinics with an AN clinic and more than 500 births per year (unit of randomisation). Women who attended the clinics and reported to be current smokers were the unit of analysis. Exclusion criteria: Under 16 years of age, too sick, non‐English speaking, illiterate, attendance was first visit. Recruitment: 23/25 public hospitals agreed to participate 22 clinics randomised (C = 11, I = 11). Assume smoking prevalence identifies eligible smokers (2284 in control clinics and 2821 in intervention clinics). Included in post‐dissemination assessment: C = 688, I = 781. Baseline characteristics: Smoking details not reported. Proportion more than high school: 22%; Language other than English at home: C = 35%, I = 33%. Progress + coding: Low SES as all attending a public pre‐natal clinic. | |
| Interventions | The cessation programme "Fresh Start for you and your baby", developed by Windsor, based on CBT, was used. More details are described in Walsh 1997. Coded as a counselling (multi‐modal) intervention. Control: Simple dissemination of programme to clinics which included mail out of written information on programme benefit and resources. Intervention: Intensive dissemination of programme which included written information and feedback about programme benefits to managers, provision of programme resources, offers of visits to explain programme and provide training, sample smoking cessation policy, regular contacts to offer support, and computerised feedback on activities. Main intervention strategy: Intensive dissemination vs less intensive dissemination. Intensity: Not coded as same intervention for women in both arms (counselling‐tailored). This study is not included in intensity analysis. Study provided by existing service providers: effectiveness/dissemination study. | |
| Outcomes | Primary outcomes were the proportion of women whose smoking status was assessed and were provided smoking cessation advice. Biochemically validated point prevalence smoking cessation at end of pregnancy* (The proportion of women who had been smokers when they first visited the clinic who had now quit, p99) was a secondary outcome for this study. Provider views of interventions discussed. | |
| Notes | No intracluster correlation or impact factor reported, so sensitivity analysis conducted using 4 ICCs and figures adjusting using ICC of 0.1 in outcome tables. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Method of random allocation not specified, but taken within strata based on clinic size and baseline smoking rates. |
| Allocation concealment (selection bias) | Unclear risk | Not specified. |
| Incomplete outcome data (attrition bias) | High risk | One clinic excluded as did not report final data and some missing data for post‐dissemination measures. No ITT of women dropping out of study. Only women completing study measures included in analysis. Unable to re‐include in this review. |
| Selective reporting (reporting bias) | Low risk | Smoking status and recall of intervention reported. |
| Other bias | High risk | There was a shorter recruitment period (1 week instead of 2 weeks) at post‐dissemination for the 11 largest clinics (out of the 22 clinics involved), so the sample sizes have been adjusted to account for the shorter recruitment period for those clinics, by increasing the sample size to what they would have expected to have recruited if the period was over 2 weeks instead of 1. We have adjusted for these estimates in this review as outlined in Table 1. Also lower recruitment in control arms compared to intervention arms. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Exhaled CO >= 9 ppm. |
| Blinding of participants and personnel (performance bias) | High risk | Educational intervention. Neither women nor providers would have been blind to the intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Process evaluation showed good implementation in intervention group. However time constraints within clinics meant that training sessions could not be repeated. Although training permitted information about the programme to be provided to clinicians and the training videotape modelled smoking cessation skills, the time period was usually inadequate to provide skill development as originally planned. p100 |
| Equal baseline characteristics in study arms | Low risk | Patient population differences on nearly all 14 characteristics were minimal (less than 5%). |
| Contamination of control group | High risk | Similar proportions of control women received the specific risk information which indicated that midwives had increased the pre‐study level of UC advice. |
| Methods | Randomised controlled trial evaluating provision of videotaped vignettes for promoting smoking cessation and relapse prevention during pregnancy. Study conducted in a community‐based university setting, Texas, USA. Data collection dates not reported. | |
| Participants | Inclusion criteria: Volunteers who were willing to quit within 2 weeks. Exclusion criteria: Women smoking < 3 cigarettes per day; < 18 years; > 30 weeks' pregnant; do not have a working video recorder (approximately 12% Americans); depressed. Recruitment: Through local media, such as newspaper, radio, subscriber letters, community business flyers, waiting room posters. 146 women screened and 82 women who met inclusion criteria were randomised (C = 40, I = 42). Baseline characteristics: Mean cigarettes/day at first visit: C = 14.5, I = 17.3. Progress + coding: None. | |
| Interventions | Control: Received a quit calendar and tip guide. Main intervention strategy: Counselling (single intervention) compared to a less intensive intervention. Intensity: Frequency (C = 2, I = 2), Duration (C = 1, I = 4). Intervention provided by study staff: efficacy study. | |
| Outcomes | Biochemically validated point prevalence abstinence obtained within 2‐3 days of quit date, 4‐5 weeks after the quit date (late pregnancy)* and 1 month postpartum (0‐5 months postpartum*). Associated references report association between quitting and depressive disorders, but not by intervention exposure. CES‐D scores at baseline only. | |
| Notes | Authors say women in this study tend to be heavier smokers than described in previous studies. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Not stated. |
| Allocation concealment (selection bias) | Unclear risk | Not stated. |
| Incomplete outcome data (attrition bias) | Low risk | Only 61% of participants completed all assessments. All those with missing data were treated as continuing smokers in this review. |
| Selective reporting (reporting bias) | Low risk | Pre‐specified outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | All reports of abstinence were validated by measurement of salivary cotinine < 30 ng/mL. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Video mailed to participants. Not clear if UC givers were aware of group allocation. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Process evaluation showed only 53% of the intervention group viewed 1‐3 of the 6 videos. 47% did not view them. |
| Equal baseline characteristics in study arms | Low risk | No significant difference in socioeconomic variables between groups. |
| Contamination of control group | Low risk | Video mailed out to participants only. |
| Methods | 2‐armed randomised controlled trial to evaluate a depression‐focused intervention which aims to promote smoking cessation during pregnancy. Study conducted in Texas (USA) between January 2005 and January 2008. | |
| Participants | Inclusion criteria: >= 16 years of age, to be <= 32 weeks pregnant, to have smoked at least a puff or more during the past 7 days, to have a telephone, and to express a willingness to quit smoking during the study (i.e. women with a goal of only reducing cigarette consumption were not eligible). Exclusion criteria: Currently participating in psychotherapy or other smoking cessation treatment, had unstable medical conditions that would adversely affect attendance, or demonstrated psychological instability during the screening (e.g. high suicide risk, symptoms of cognitive disorder, or severe intellectual impairment). Recruitment: Through newspaper and television advertisements, and physician referrals. 730 women were screened for basic eligibility by telephone. 266/294 (90%) eligible women were randomised (C = 133, I = 133). Baseline characteristics: Smoking rate before finding out pregnant (mean cigarettes per day): I = 16.8 (8.7), C = 15.8 (9.1); 63% receiving medicaid or county health care, 54% African‐American, 10% Hispanic, 33.5% Caucasian; 31.9% had less than high school education. 34.2% had family income < $10,000. 75.5% had lifetime major depressive disorder (23.5% current major disorder). Progress + coding: Ethnic minority. | |
| Interventions | Ten individual counselling sessions were scheduled for 60 min. Each session consisted of 15 min of standard behavioural and motivational smoking cessation counselling (common to both groups). Counselling typically involved active efforts to prepare for quitting and maintaining abstinence using self‐monitoring of their smoking prior to the quit date, identification of high‐risk situations for smoking, and development of coping skills and support before and after the quit date. Therapists used motivational enhancement strategies based on techniques of MI if resistant to quitting. The core features included exploration of participant ambivalence, use of open‐ended questions, reflective listening, expressed empathy, rolling with resistance, and use of strategies to develop perceived discrepancy between smoking behaviour and important personal goals and values. Control: The primary goal of the HW treatment was to educate women on ways to decrease stress, to respond to stressful events, and to take care of themselves physically during their pregnancies. The purpose was to provide a time‐ and attention‐matched control for CBASP that was pregnancy relevant but instructional in nature—typical of health‐education interventions. Participants chose from a list of discussion topics, including stress, pregnancy symptoms, sleep, exercise, yoga, relaxation training, time management, parenting tips, dealing with anger, negative thoughts and feelings, and postpartum depression. Main intervention strategy: Counselling (single intervention) compared to alternative intervention. Intensity: Frequency (C = 6, I = 6); Duration (C = 6, I = 6). Intervention provided by study staff: efficacy study. | |
| Outcomes | Biochemically validated 7‐day point prevalence abstinence at end of 10 weeks treatment (late pregnancy*), self‐reported smoking cessation 3 and 6 months after treatment, smoking cessation 3 (0‐5*) and 6 (6‐11*) months postpartum. Continuous and prolonged abstinence also reported. Depression (CES‐D scores) and probability of cessation 6 months post‐treatment. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Adaptive randomisation was used to stratify the groups on age, race, history of depression, baseline smoking rate, baseline depressive symptom severity (CES‐D >= 16), and longest duration of last depressive episode. |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition: 3 months: C = 9/133, I = 22/133; 6 months C = 42/133, I = 54/133. All analyses were carried out on the ITT sample, which included 128 participants in the Intervention group and 129 control — excluding only those who experienced a miscarriage during the study (5 participants in Intervention and 4 participants in control). |
| Selective reporting (reporting bias) | Low risk | All primary outcomes reported |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation of self‐reported smoking status (7‐day point prevalence only) using expired CO (< 4 ppm) throughout treatment or salivary cotinine (< 15 ng/mL) with self‐report only at 3‐ and 6‐month follow‐up contacts. |
| Blinding of participants and personnel (performance bias) | High risk | Participants and providers unlikely to be blinded to counselling intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | Process evaluation showed high levels of compliance with counselling standards in both groups. Participants attended an average of 8/10 sessions of approximately 58 mins. |
| Equal baseline characteristics in study arms | Low risk | No significant differences noted. |
| Contamination of control group | Low risk | There is a potential risk with the same counsellors providing counselling for the intervention and control groups. However global competence ratings for CBASP, HW, and the smoking cessation counselling interventions were measured on a scale ranging from 1 (does not attempt intervention) to 4 (good use of intervention). No differences in competence between the groups were noted, averaging 3.8 (SD across conditions. Statistical agreement of competence ratings between primary and secondary raters was high, with a Cohen’s kappa (Landis & Koch, 1977) of .93 (95% CI 0.86 to 1.0) |
| Methods | Randomised controlled trial of counselling to support women to stop smoking during pregnancy in the USA. Location and dates of data collection not reported (abstract only available). | |
| Participants | Inclusion criteria: Self‐reported smokers presenting for prenatal care before 24 weeks' gestation. Exclusion criteria: Not specified. 150 women randomised. Data for only 43 women (C = 20, I = 23) who had delivered by the time of report are available. 2 women in control group had baseline cotinine levels consistent with abstinence so are not included (C = 18, I = 23). Baseline characteristics: Not reported. Progress + coding: None. | |
| Interventions | Control: Discussion of smoking risks by a nutritionist and again by a resident physician at initial prenatal visit. Intervention: Control + regular meetings with a smoking cessation counsellor and physician reinforcement at each visit. The women also received biochemical feedback from urine cotinine. Main intervention strategy: Counselling (multiple intervention) compared to a less intensive intervention. Intensity: Frequency (C = 1, I = 5); Duration (C = 1, I = 3). Estimates for intervention as little detail provided. Intervention provided by routine care staff: effectiveness study. | |
| Outcomes | Biochemically validated point prevalence abstinence at term or birth (late pregnancy*); > 50% reduction in cotinine*; and mean birthweight*. | |
| Notes | SDs for mean birthweight were not reported, therefore we calculated a mean SD from 13 studies with available birthweight SDs (578) to include in this review, as recommended by the cochrane handbook. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Not reported. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Unclear risk | One woman in the intervention group dropped out of the study and was not included in the original analysis but has been re‐included as a continuing smoker in this review, but not included in the mean birthweight analysis. |
| Selective reporting (reporting bias) | High risk | Preliminary results only available. Final results not reported and unable to be accessed. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation by urine cotinine but cut‐off levels not reported. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible for participants and personnel to be blinded to counselling intervention |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Not reported. |
| Equal baseline characteristics in study arms | Unclear risk | Baseline characteristics not reported (abstract only). |
| Contamination of control group | High risk | Appears that same physician provided advice to control and intervention women, and not clear if this was not repeated for control group. |
| Methods | 2‐armed randomised controlled trial evaluating effectiveness of feedback from a point‐of‐care cotinine test for supporting women to stop smoking during pregnancy. Study conducted in Birmingham, UK. Dates of data collection not reported. | |
| Participants | Inclusion criteria: 'Current smokers' (> 10 mg/L in preliminary urine cotinine result). Exclusion criteria: Not specified. Recruitment: Seen at initial AN visit and given brief explanation of test and aims of research, and asked to give verbal consent to participate in study. Women then had urine screened for cotinine and completed a questionnaire. 745/856 (87%) eligible women agreed to participate and were randomised (C = 447, I = 298 in flow chart and 409 in results text). 280 women were smokers (C = 164, I = 116). Baseline characteristics: Average consumption of 11.8 cigarettes per day. Other characteristics not reported. Progress + coding: None | |
| Interventions | Control: Routine counselling from a doctor or midwife. Urine measured at initial visit but no feedback given to woman. Intervention: 6‐min urine test completed in their presence. Results given as a number and graphic illustration. A specific quit date within the next 14 days was mutually agreed and the woman was given a printed leaflet containing practical advice on how to reduce their smoking measurement at each visit. A positive friendly attitude of providers ‐ information, feedback, encouragement protocol was repeated whenever the patient returned to the clinic up to and including the 36 week visit, with measurement, questioning about changes in smoking, specific events on the quit date and reinforcement of advice. Main intervention strategy: Feedback (multiple intervention) compared to UC. Intensity: Frequency (C = 0, I = 5); Duration (C = 0, I = 3). UC intensity: F = 1, D = 1. Intervention provided by study staff: Efficacy study. | |
| Outcomes | Biochemically validated point prevalence smoking cessation at 36 weeks' gestation (late pregnancy*). Proportion with 'some reduction*' (20% to 80% urine cotinine). Mean birthweight* and length. Preterm births* reported in attrition and re‐included in both numerator and denominator for this outcome. Gestation, type of delivery, and Apgar scores collected but results not reported. Participants view of interventions reported. | |
| Notes | SDs for mean birthweight were not reported, therefore we calculated a mean SD from 13 studies with available birthweight SDs (578) to include in this review, as recommended by the cochrane handbook | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | High risk | Quasi‐randomised: New referrals to 3 large inner‐city hospital AN clinics were randomised on the basis of their allocated hospital unit number, even numbers being placed in the case or intervention group, or those who were provided with feedback from the smoking test at point of care. p675 |
| Allocation concealment (selection bias) | High risk | Group allocation could be anticipated. |
| Incomplete outcome data (attrition bias) | Unclear risk | Only 83/116 women in the control group and 109/164 women in the intervention group completed the study. Those who dropped out for medical reasons: miscarriage (C = 2, I = 3) or premature delivery (C = 6, I = 13), or transferred care (C = 3, I = 5) were excluded (C = 11, I = 21) from smoking outcome analysis. Those who failed to attend appointments, or refused further involvement were re‐included as continuing smokers in this review (C = 18, I = 34), leaving a total sample of C = 101, I = 143. |
| Selective reporting (reporting bias) | Low risk | Primary outcomes appear to be reported. |
| Other bias | High risk | Clear financial conflict of interest declared by author (directorship of company producing feedback tests). |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking status biochemically validated with urine cotinine (> 10 mg/L indicates active smoker). |
| Blinding of participants and personnel (performance bias) | High risk | Neither providers nor women were blind to intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Not reported. |
| Equal baseline characteristics in study arms | Unclear risk | Not reported. |
| Contamination of control group | Low risk | Contamination unlikely with provision of specific biochemical test. |
| Methods | Randomised controlled trial of "Significant Other Supporter" (SOS) program, of social support and direct financial rewards to reduce smoking during pregnancy and postpartum. Study conducted in Oregon WIC program sites, USA, between June 1996 and June 1997. | |
| Participants | Inclusion criteria: Women smoking (even a puff in the last 7 days); less than 28 weeks' gestation; over 15 years of age; literate in English. Exclusion criteria: Not specified. Recruitment: 220/309 (71%) eligible women were randomised (C = 108, I = 112). Baseline characteristics: Mean salivary cotinine at baseline: I = 45.4; C = 45.7. Caucasian (I = 90%, C = 88%), household income < $20000 (I = 87%, C = 89%), Single (I = 47%, C = 42%), Mean age (I = 23.5, C = 24.0). Progress + coding: Low SES. | |
| Interventions | Control: Verbal and written information on the importance of smoking cessation, a pregnancy specific smoking cessation self‐help kit, and monthly telephone calls for self‐reports on their smoking status. Main intervention strategy: Incentives (multiple intervention) compared with a less intensive intervention. Intensity: Frequency (C = 2, I = 6), Duration (C = 1, I = 3)‐estimated duration as limited information available. The intervention was delivered by trained program staff or research staff: efficacy study. | |
| Outcomes | Biochemically validated 7‐day point prevalence smoking cessation at 34 weeks' gestation (late pregnancy*) and 2 (0‐5*) months postpartum. | |
| Notes | Data in outcome tables is inconsistent. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | No information provided. |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | Low risk | High attrition rates I = 32%; C = 51.5% (reasons not specified), but all dropouts included as continuing smokers in this analysis. |
| Selective reporting (reporting bias) | Low risk | Main outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | 7‐day point prevalence validated by salivary cotinine analysis (> 30 ng/mL considered to be smokers). Salivary thiocyanate also used to confirm non‐smokers for immediate feedback only (> 100 ug/mL considered to be smokers). |
| Blinding of participants and personnel (performance bias) | High risk | Neither providers nor women were blinded for this educational intervention with incentives. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | No process evaluation reported. |
| Equal baseline characteristics in study arms | Low risk | Preliminary analysis indicates no significant differences exist between randomised groups on baseline demographic characteristics. |
| Contamination of control group | Low risk | Control group not reported clearly ‐ however intervention given by trained research staff rather than UC providers so unlikely that there was contamination |
| Methods | Randomised controlled trial of medical advice to stop smoking in pregnancy. Study conducted in 3 public maternity units in the UK. Dates of data collection not stated. | |
| Participants | Inclusion criteria: Pregnant women < 35 years; currently smoking >= 5 cigarettes/day and had been smoking >= 1/day at the onset of pregnancy; < 30 weeks' gestation at first visit; no prior perinatal death; not seeking termination. Exclusion criteria: Not further specified. Recruitment: Consecutive series of patients who contacted 3 maternity units regarding confinement were posted reply‐paid questionnaires (including smoking questions), which were used to select eligible participants. 588 women provided consent and were randomised. Baseline characteristics: Mean cigarettes/day at beginning of pregnancy (C = 17.6, I = 17.9); mean cigarettes/day at study entry (C = 15.2, I = 15.2), Mean age (C = 24.2, I = 23.8). Even distribution of social class categories. Progress + coding: None. | |
| Interventions | Control: ANC usually provided by the hospital, including any anti‐smoking advice which may have been given routinely. Intervention: Individualised medical advice by clinic doctor, Details of the intervention are in Donovan 1975. Main intervention strategy: Health education (single intervention) compared to UC. Intensity: Frequency (C = 0, I = 5); Duration: (C = 0, I = 2)‐estimate. UC intensity: F = 1, I = 1. Intervention provided by existing service providers: effectiveness study. | |
| Outcomes | Self‐reported mean cigarettes/day at 4 stages of pregnancy (late pregnancy*), mean birthweight*, LBW*, preterm birth* (< 36 weeks), perinatal deaths*. No data on smoking cessation. | |
| Notes | Discussion of common problems identified when advising women to stop and on the contextual factors which encourage the continuation of smoking. Actual standard errors were able to be incorporated into software for this update (previously SD 500 used), so effect size estimates have altered slightly. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Table of random numbers. |
| Allocation concealment (selection bias) | Unclear risk | Information not provided. |
| Incomplete outcome data (attrition bias) | Low risk | Twins (C = 2, I = 6) and miscarriages (C = 17, I = 11) not included in analysis. 552 women analysed (C = 289, I = 263). No further attrition reported. |
| Selective reporting (reporting bias) | Unclear risk | Smoking cessation rates not reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | No biochemical validation of reported smoking behaviour. |
| Blinding of participants and personnel (performance bias) | High risk | Notes labelled. Caregivers asked to reinforce information. Educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Process evaluation of the reinforcement of advice showed little difference between the groups in recall of advice being given. |
| Equal baseline characteristics in study arms | Unclear risk | From table 2 characteristics appear to be equal ‐ but there is no statement or statistic confirming this. |
| Contamination of control group | High risk | Same providers offering intervention and control advice. Process evaluation of the reinforcement of advice showed little difference between the groups in recall of advice being given. |
| Methods | Randomised controlled trial of counselling and telephone support to support women to stop smoking during pregnancy and postpartum. Study conducted in Hartford, Connecticut (USA), between January 2001 and December 2002. | |
| Participants | Inclusion criteria: Pregnant women, over 18 years old, less than 30 weeks' gestation, current smokers (recent quitters included in associated relapse prevention paper (Morasco 2006). Exclusion criteria: Recent history of abuse or dependence on alcohol or other non‐nicotine substance, major psychiatric illness, no access to a telephone. Recruitment: Study conducted in the prenatal clinic of a non‐profit tertiary care community hospital. Written consent obtained. Unclear how many eligible women participated. 140 women enrolled in study. 33 spontaneously quit (C = 19, I = 14), 107 were randomised but 2 were excluded due to missing data, leaving 105 included in analysis (I = 53, C = 52). Baseline characteristics: 70.5% smoked less than 10 cigarettes per day at baseline. Mean 20.8 (12.37) pre‐pregnancy. 66% Hispanic, 17% Caucasian, 11% African American. 61% unemployed, 54% less than high school education, 60% single, 49% household income < $15000/yr, 52% 1 or more depression items and 19% all 4 items. Progress + coding: Low SES and minority ethnic group. | |
| Interventions | Control: UC according to standard smoking cessation guidelines, with providers offered 2 x 1‐hour training sessions. Research study co‐ordinator provided all participants with a booklet, inserted a chart prompt to remind providers to provide personalised quit messages at each visit, and audited charts to ensure the advice was documented. Intervention: 1 90‐min psychotherapy session provided by masters‐prepared mental health therapist trained in smoking cessation. The main goals were to assess readiness to quit, identify potential psychological or social problems that might pose as barriers to quitting, and set a quit date. This was followed by bi‐monthly telephone calls from the therapist during pregnancy, and monthly calls after delivery. Main intervention strategy: Counselling (single intervention) compared to a less intensive intervention. Intensity: Frequency (C = 5, I = 6), Duration (C = 2, I = 6). Intervention provided by study staff: efficacy study. | |
| Outcomes | Biochemically validated 7‐day point prevalence abstinence in late pregnancy* and 6 (6‐11) months postpartum*. Aggregated results by week of gestation to enter study. An associated study (Morasco 2006) reports abstinence rates for recent quitters (relapse prevention*). Cost‐effectiveness of 'cost per quitter'. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | No description of methods of randomisation. |
| Allocation concealment (selection bias) | Unclear risk | No description. |
| Incomplete outcome data (attrition bias) | High risk | 2/107 randomised women were excluded from analysis due to missing data and were unable to be re‐included in this report as the group allocation is not reported. The remaining dropouts (18% at 6 months postpartum) are included as continuing smokers in this analysis. |
| Selective reporting (reporting bias) | Low risk | All outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation with exhaled CO readings (cut off < 8 ppm but all participants less than 4 ppm). |
| Blinding of participants and personnel (performance bias) | High risk | Educational intervention so blinding not feasible. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Process evaluation showed 17/53 did not receive the phone calls as planned. |
| Equal baseline characteristics in study arms | Unclear risk | No significant differences in any of the baseline characteristic between the 2 groups |
| Contamination of control group | Low risk | Counselling and follow‐up sessions provided by psychotherapist not involved in UC. |
| Methods | Randomised controlled trial of midwifery counselling to support women to stop smoking in pregnancy. Study conducted in a large UK maternity service. Data collection dates not specified. | |
| Participants | Inclusion criteria: Pregnant and booked for maternity care; < 18 weeks' gestation; currently smoking 1 or more cigarettes/day. Practising midwives regularly attending AN clinic.13 midwives selected for the intervention group and 13 for the control group. Exclusion criteria: Not specified. Recruitment: All women identified as smokers in a busy teaching hospital with 3700 deliveries a year received a letter asking if they would like to participate. 100 women participated (described as 'all 100 women contacted') and were randomised (C = 50, I = 50). Baseline characteristics: 'Contemplators' (C = 70%, I = 60%), 'pre‐contemplators' (C = 15%, I = 22%), 'ready for action' (C = 15%, I = 18%). No other baseline characteristics reported. Progress + coding: None. | |
| Interventions | Control: UC. Intervention: Midwives were trained to assess the stages of change and provide a behavioural intervention, using the Health Education Authority material "Helping pregnant smokers quit: training for health professionals", 1994. Main intervention strategy: Counselling (single intervention) compared to UC. Intensity: Frequency (C = 0, I = 5), duration (C = 0, I = 2)‐based on estimated brief contact (< 5 min) at a standard number of AN visits (8), as very little information about intervention provided. UC intensity: F = 0, I = 0. Intervention provided by existing staff: effectiveness study. | |
| Outcomes | Self‐reported smoking cessation at 37 weeks (late pregnancy)*; and at 4 weeks (0‐5 months*) postpartum. Reduction in cigarettes/day (not reported as results unclear), "stage of change" at 11 to 18 weeks vs 37 weeks. No biochemical validation of smoking status. Care providers' views discussed. | |
| Notes | No process evaluation reported. Abstract data used. States 'after one year' which is assumed to be of year of the study, at 37 weeks' gestation, as reported in figure 1. As there were no quitters in the control group, the relapse rates of 4% within 1 month postpartum are assumed to be from the treatment group only. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Not stated. |
| Allocation concealment (selection bias) | Unclear risk | Described as 'randomly allocated'. |
| Incomplete outcome data (attrition bias) | Low risk | 94 of 100 randomised women followed up (reasons for attrition not reported). No ITT analysis reported. However, all dropouts re‐included as continuing smokers in this review. |
| Selective reporting (reporting bias) | Unclear risk | All outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | No biochemical validation of reported smoking status. |
| Blinding of participants and personnel (performance bias) | High risk | Participants and personnel unlikely to be blinded to educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Not reported. |
| Equal baseline characteristics in study arms | Unclear risk | Not reported. |
| Contamination of control group | Low risk | Midwives randomised so low risk of contamination. |
| Methods | Randomised controlled trial which aims to promote smoking cessation and relapse prevention during pregnancy and postpartum. The study was conducted in 3 urban community‐controlled health services in far north Queensland and Western Australia June 2005 and December 2009. | |
| Participants | Inclusion criteria: Pregnant Aboriginal or Torres Strait Islander women attending their first AN appointment at 1 of the Aboriginal community‐controlled health services at or before 20 weeks’ gestation; were aged 16 years or older, were self‐reported current smokers or recent quitters (quitting when they knew they were pregnant); and were residents of the local area. Exclusion criteria: Women whose pregnancy was complicated by a mental illness or they were receiving treatment for chemical dependencies other than tobacco or alcohol use. Recruitment: 1119/1180 women attending the AN clinic were assessed for eligibility. 263/379 (69%) eligible women agreed to participate (C = 115, I = 148). Baseline characteristics: Median cigarettes per day: C = 10 (4‐15), I = 10 (5‐15); Spontaneous quitting since pregnancy: C = 8, I = 24. 100% Aboriginal and Torres Strait Islander women. Partner (C = 88%, I = 92%). Progress + coding: Low SES and minority ethnic group. | |
| Interventions | Control: UC consisting of general advice from a GP about quitting smoking, based on existing brief intervention guidelines. Intervention: Intervention developed after review of the literature and consultation with service providers and community members. At first AN visit women received a scripted invitation from the doctor to quit smoking and advised to quit 'cold turkey' and return to the clinic in 3‐5 days and at 7‐10 days. The woman received an appointment reminder card, fridge magnet, and a letter for other household members requesting their support. Women were asked to bring a partner or support person with them on their second visit. Women still smoking after 7‐10 days were offered NRT if no contra‐indications. Follow‐up visits were conducted by female Aboriginal or Torres Strait Islander health workers and midwives who received training from a behavioural scientist and a GP, a study manual and a 1 page guide with scripted advice. Main intervention strategy: Counselling (tailored) compared to UC. Intensity: Frequency (C = 0, I = 4), Duration (C = 0, I = 3). UC intensity: F = 1, D = 1. Existing staff delivered intervention: effectiveness study. | |
| Outcomes | Biochemically validated point prevalence smoking abstinence* and relapse prevention* at 36 weeks' gestation (late pregnancy). Postpartum cessation (6 months) not reported due to very high rates of attrition. | |
| Notes | Cluster‐randomisation by weeks but number of weeks not reported. No analysis for adjustment for clustering reported. Treated as individually‐randomised controlled trial in this review. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | An Excel computer program was used to randomly allocate weeks to intervention or control for all clinics. |
| Allocation concealment (selection bias) | High risk | Author notes lack of allocation concealment a methodological limitation of the study, which may account for unequal allocation in study arms. |
| Incomplete outcome data (attrition bias) | Low risk | High rates of attrition (C = 37/115, I = 50/148) at end of pregnancy (reasons not reported). Very high attrition at 6 months postpartum. ITT analysis. Women lost to follow‐up or with missing smoking status were classified as current smokers. |
| Selective reporting (reporting bias) | Unclear risk | 6 months postpartum outcomes not reported due to high attrition. |
| Other bias | High risk | Unequal numbers in each group with greater allocation to intervention groups. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Self‐reported smoking cessation biochemically validated using urinary cotinine (< 250 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Clinic staff made aware of treatment allocation at beginning of each week and unlikely participants were blinded. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Outcome assessor blinding not reported. |
| Incomplete implementation | High risk | 64% doctors adhered to protocol and a lower proportion of nurses and health workers. |
| Equal baseline characteristics in study arms | High risk | A slightly higher proportion of intervention group were in clinic 1, a slightly lower proportion had a partner, and had recently quit. |
| Contamination of control group | High risk | Same AN care providers delivered intervention and control arms. High likelihood of contamination noted in discussion. |
| Methods | This randomised controlled trial examines whether an integrated behavioural intervention improves pregnancy outcomes, including smoking cessation. The study was conducted in 6 community‐based clinical sites serving minority women (African‐Americans and Hispanics) in Columbia, USA, from July 2001 to July 2004. | |
| Participants | Inclusion criteria: Women attending prenatal care in 6 community‐based sites who self‐identified as belonging to a minority group, being >= 18 years, Exclusion criteria: Suicidal women. Recruitment: 2913 women approached while waiting for prenatal appointments. 1044/1398 (75%) eligible women provided signed consent to participate in the study (C = 523, I = 521). 302 women reported smoking '1+ puff in the preceding 6 months and 198 reported 'active' smoking at baseline. These 198 'active' smokers at baseline are included in this analysis (C = 92, I = 106). Baseline characteristics: 100% African American, 43.7% reliant on social housing, ˜80% Medicaid recipients. Progress + coding: Minority ethnic group and low SES. | |
| Interventions | Control: Not reported‐UC. Intervention: The 10‐session intervention was delivered during prenatal (eight sessions) and postpartum (2 booster sessions) care visits. 4 prenatal sessions were considered minimal adherence. The session duration was approximately 35 min. The smoking intervention was consistent with the Smoking Cessation or Reduction in Pregnancy Trial (SCRIPT) and the Counseling and Behavioral Interventions Work Group of the United States Preventive Services Task Force recommendations, a 5‐step behavioral counselling approach. The intervention was tailored to the woman’s stage of change. Women were encouraged to avoid triggers and to use alternative coping and behavioural change strategies. The intervention included content to address both active smoking and ETSE, whether or not they met criteria for ETSE. Women with other risk factors (IPV, depression and drug or alcohol use) also received additional targeted interventions to address those issues. Main intervention strategy: Maternal health intervention with smoking component: Counselling (single intervention) compared to UC. Intensity: Frequency (C = 0, I = 5), Duration (C = 0, I = 5). Intervention provided by study staff: efficacy study. | |
| Outcomes | Biochemically validated smoking cessation prior to delivery* (late pregnancy) and at 8‐10 weeks (0‐5 months*) postpartum. Mean urine cotinine*. Outcomes also reported by intervention group for environmental tobacco smoke exposure, depression, intimate partner violence and illicit drug use. Detailed pregnancy outcomes reported but not included in this analysis as they were not reported by smoking status at baseline, and these outcomes may be affected by several of the multi‐modal interventions aimed at reducing risk factors other than smoking. | |
| Notes | Detailed participant satisfaction and intervention acceptability was reported in an associated reference (Katz 2008). | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Site‐ and risk‐specific block randomisation to IG or UCG was conducted. A computer‐generated randomisation scheme considered all possible risk combinations within each of the recruitment sites. |
| Allocation concealment (selection bias) | Low risk | Investigators and field workers were blinded to the block size. Recruitment staff at each site called in the details of the risk profile for a new recruit, and the assignment was generated centrally by the data co‐ordinating centre. |
| Incomplete outcome data (attrition bias) | Low risk | Attrition: 104/500 (21%) prior to delivery and 116/500 (23%) in the postpartum assessment. Participant data were analysed according to their care group assignment, regardless of whether they received any intervention sessions, using an ITT model. |
| Selective reporting (reporting bias) | Unclear risk | Data on women spontaneously quitting before pregnancy were not reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking cessation biochemically validated using salivary cotinine (< 10 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Participants and providers not able to be blinded by dedicated intervention providers minimised risk of contamination of study arms. |
| Blinding of outcome assessment (detection bias) | Low risk | 4 research teams were allocated to ensure blinding of outcome assessors. |
| Incomplete implementation | High risk | Process evaluation showed 16% women did not attend any sessions, 43% randomised women did not complete first follow‐up interview and 31% did not complete 2nd follow‐up interview. |
| Equal baseline characteristics in study arms | Low risk | No significant differences noted. |
| Contamination of control group | Low risk | Persons delivering intervention were separate from care provider team. |
| Methods | Randomised controlled trial of self‐help booklets to support women to stop smoking in pregnancy. Study conducted in 5 health centres of the same HMO in Los Angeles (USA), from 1985 to 1987. | |
| Participants | Inclusion criteria: English‐speaking women attending 1 of 5 health centres for prenatal care, < 18 weeks' gestation; still smoking >= 7 cigarettes a week. Exclusion criteria: Not specified further. Recruitment: 323 who self‐reported still smoking >= 7 cigarettes/week were randomised (C = 158, I = 165). 242 included in final analysis (C = 116, I = 126). 228 women who had spontaneously quit also included (C = 108, I = 110). Baseline characteristics (smokers): Prepregnancy smoking: 27.3% 1‐10 cigarettes/day, 14% 11‐19 cigarettes/day, 58.7% 20 + cigarettes/day. At intake: 71.9% 1‐10 cigarettes/day, 14.9% 11‐19 cigarettes/day, 13.2% 20 + cigarettes/day. Spontaneous quitters: mean pre‐pregnancy cigarettes/day = 10.3. Smokers: 64% white, 73% had high school or some college education, 59.9% married. Progress + coding: None. | |
| Interventions | Control: 2‐page pamphlet on hazards of smoking and on the need to quit; 2 mins discussion with a health educator (within a 45 mins individual conference); advised of free 5 session smoking cessation program available through the HMO. Coverage in AN classes remained unchanged. Main intervention strategy: Counselling (single intervention) compared to less intensive intervention. Intensity: Frequency (C = 6, I = 6), Duration (C = 4, I = 4). Estimate based on uptake of optional HMO sessions x 5 approximately 20‐40 mins. Intervention provided by existing health staff: effectiveness study. | |
| Outcomes | Biochemically validated abstinence at 34 weeks' gestation (late pregnancy*). Ershoff 1995 reports relapse prevention* among women who had spontaneously quit. Ershoff 1990 reports birth outcomes (mean birthweight*, LBW*, preterm birth* (< 37 weeks), very preterm birth (< 34 weeks), stillbirths*, 'confidence in ability to quit' and cost outcomes (economic evaluation). Associated reference (Mullen 1991) describes question structure's to improve accurate disclosure of smoking status. | |
| Notes | SDs for mean birthweight were not reported, therefore we calculated a mean SD from 13 studies with available birthweight SDs (578) to include in this review, as recommended by the cochrane handbook | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | No information |
| Allocation concealment (selection bias) | High risk | The authors state that women had been randomised in advance of their visit. It was not clear how women were recruited to the study or gave consent for participation. The health educator turned over a 'pre‐assigned card' to randomise women. |
| Incomplete outcome data (attrition bias) | Unclear risk | Smokers: Attrition I = 39/165, C = 44/158 not included in analysis. Losses due to termination (C = 11, I = 7); miscarriage (C = 13, I = 12); disenrolment or transfer to another HMO (C = 18, I = 20). Spontaneous quitters: Attrition 22% ‐ Abortion (n = 5), miscarriage (n = 17), disenrolment from HMO or transfer (n = 25). Not re‐included in analysis for this review as excluded for medical reasons or moving. |
| Selective reporting (reporting bias) | Unclear risk | None apparent. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation by urinary cotinine levels. For participants reporting no smoking and low exposure to passive smoke urine cotinine had to be less than or equal to 10 ng/mL. For participants reporting a relapse and high exposure to passive smoke some values could be as high as 29 ng/mL though at least 1 sample had to be 10 ng/mL or less. |
| Blinding of participants and personnel (performance bias) | Unclear risk | The authors state that the health educator delivering the intervention was not aware of group allocation, but materials were provided to the experimental group at the clinic visit. Prenatal care providers were blinded to group assignment and no effort was made to modify their usual counselling practices. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | Process evaluation reports good implementation. |
| Equal baseline characteristics in study arms | Unclear risk | With the exception of partners smoking status. |
| Contamination of control group | Low risk | Prenatal care providers not involved in intervention so risk of contamination likely to be low. |
| Methods | 3‐armed randomised controlled trial of interactive computer program and telephone counselling to support women to stop smoking in pregnancy. Study conducted in a large group model managed care organisation in Los Angeles, California (USA) with recruitment from November 1996 to June 1997. | |
| Participants | Inclusion criteria: Smokers were identified at first visit as women who self‐report "smoking now", "smoke but have cut down since pregnancy", or "smoke from time to time". Exclusion criteria: < 18 years of age, > 26 weeks' gestation, do not speak English, or smoked less than 7 cigarettes pre‐pregnancy. Recruitment: Researchers attempted to phone 931 women. 150 could not be contacted, 90 refused to be interviewed, 158 were not eligible and 34 were excluded as they experienced miscarriage (n = 34). 390/458 women (82%) agreed to participate (C = 131,I1 = 133, I2 = 126). Baseline characteristics: Pre‐pregnancy mean cigarettes per day: C = 17.1 (9.7), I1 = 17.6 (9.8), I2 = 16.3 (7.6). Mean cigarettes per day at intake: C = 6.6(7.3), I1 = 6.7(6.5), I2 = 6.3(6.5). 60% white, approximately 50% college educated, with a mean age of 29.4. Mean cigarette/day at first visit = 6.6. Progress + coding: None. | |
| Interventions | 3 interventions, based on stages of change model. Main intervention strategy: Health education (tailored intervention) compared to a less intensive intervention (self‐help booklet). This study ID compares arms A and B, see Ershoff 1999 (AvC) for A and C. Intensity: Frequency (C = 2, I = 2), Duration (C = 1, I = 1). Intervention provided by study staff: efficacy study. | |
| Outcomes | Biochemically validated smoking cessation at 34 weeks' gestation (late pregnancy*). Mean cigarettes per day*. Baseline mental health index and Cohen's perceived stress scale. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as "random assignment" |
| Allocation concealment (selection bias) | Unclear risk | No information. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition 58/390 (14.87) due to abortion (n = 31), disenrolment from health plan (n = 22) and preterm birth less than 32 weeks (n = 5). Lost to follow‐up not included as continuing smokers in analysis as attrition due to medical reasons and moving not re‐included in this review, and attrition from each study group not reported separately. 332 included in analysis (C = 111, I1 = 120, I2 = 101). |
| Selective reporting (reporting bias) | Unclear risk | Results were difficult to interpret. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation by urinary cotinine levels (< 80 ng/mL). |
| Blinding of participants and personnel (performance bias) | Unclear risk | Authors state that care providers were blind to group allocation. Educational intervention so blinding women not feasible. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported |
| Incomplete implementation | Low risk | Good process evaluation of each of the methods. 79.2% received at least 1 call. Mean 4 calls lasting 12 mins each. |
| Equal baseline characteristics in study arms | Low risk | No significant differences reported. |
| Contamination of control group | High risk | 11% control group received individual smoking cessation counselling as they were classified as high‐risk patients. |
| Methods | 3‐armed randomised controlled trial of interactive computer program and telephone counselling to support women to stop smoking in pregnancy. Study conducted in a large group model managed care organisation in Los Angeles, California (USA) with recruitment from November 1996 to June 1997. | |
| Participants | Inclusion criteria: Smokers were identified at first visit as women who self‐report "smoking now", "smoke but have cut down since pregnancy", or "smoke from time to time". Exclusion criteria: < 18 years of age, > 26 weeks' gestation, do not speak English, or smoked less than 7 cigarettes pre‐pregnancy. Recruitment: Researchers attempted to phone 931 women. 150 could not be contacted, 90 refused to be interviewed, 158 were not eligible and 34 were excluded as they experienced miscarriage (n = 34). 390/458 women (82%) agreed to participate (C = 131,I1 = 133, I2 = 126). Baseline characteristics: Pre‐pregnancy mean cigarettes per day: C = 17.1 (9.7), I1 = 17.6 (9.8), I2 = 16.3 (7.6). Mean cigarettes per day at intake: C = 6.6(7.3), I1 = 6.7(6.5), I2 = 6.3(6.5). 60% white, approximately 50% college educated, with a mean age of 29.4. Mean cigarette/day at first visit = 6.6. Progress + coding: None. | |
| Interventions | 3 interventions, based on stages of change model. Main intervention strategy: Counselling (single intervention) compared to a less intensive intervention (self‐help booklet). This study IDI compares arms A and C, please see Ershoff 1999 (AvB) for A and B. Intensity: Frequency (C = 2, I = 5), Duration (C = 1, I = 3). Intervention provided by study staff: efficacy study. | |
| Outcomes | Biochemically validated smoking cessation at 34 weeks' gestation (late pregnancy*). Mean cigarettes per day*. Baseline mental health index and Cohen's perceived stress scale. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as "random assignment" |
| Allocation concealment (selection bias) | Unclear risk | No information. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition 58/390 (14.87) due to abortion (n = 31), disenrolment from health plan (n = 22) and preterm birth less than 32 weeks (n = 5). Lost to follow‐up not included as continuing smokers in analysis as attrition due to medical reasons and moving not re‐included in this review, and attrition from each study group not reported separately. 332 included in analysis (C = 111, I1 = 120, I2 = 101). |
| Selective reporting (reporting bias) | Unclear risk | Results were difficult to interpret. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation by urinary cotinine levels (< 80 ng/mL). |
| Blinding of participants and personnel (performance bias) | Unclear risk | Authors state that care providers were blind to group allocation. Educational intervention so blinding women not feasible. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported |
| Incomplete implementation | Low risk | Good process evaluation of each of the methods. 79.2% received at least 1 call. Mean 4 calls lasting 12 mins each. |
| Equal baseline characteristics in study arms | Low risk | No significant differences reported. |
| Contamination of control group | High risk | 11% control group received individual smoking cessation counselling as they were classified as high‐risk patients. |
| Methods | Randomised controlled trial of counselling and a self‐help guide to support women to stop smoking during pregnancy. Study conducted in Baltimore (USA). Study dates not reported. | |
| Participants | Inclusion criteria: Pregnant women currently smoking (even 1 puff in the past 7 days), either African‐American or white. Exclusion criteria: > 28 weeks' gestation; changing to another prenatal clinic or could not complete baseline interview. Recruitment: 2319 women assessed, 32% currently smoking by above definition. 72 were excluded for gestation, ethnicity or changing providers, leaving 662 eligible of whom 510 agreed to participate (77%). 25 quit prior to first visit, 18 did not wish to quit, leaving 467 (C = 235, I = 232) randomised. Baseline characteristics: Mean cigarettes/day at intake I = 9.7, C = 7.5 (P = 0.01). 85% were on medical assistance. African American: I = 81% C = 89%. Progress + coding: Low SES and ethnic minority population. | |
| Interventions | Control: Usual clinic and inpatient smoking cessation: A brief discussion with a nurse/health counsellor about the risks of smoking; a recommendation to quit and pamphlets from the area's voluntary agencies. Main intervention strategy: Counselling (multiple intervention) compared to UC. Intensity: Frequency (C = 0, I = 6), Duration (C = 0, I = 2). UC intensity F = 1, I = 1. Intervention provided by study staff: Efficacy study. | |
| Outcomes | Biochemically validated 7‐day point prevalence abstinence in hospital after delivery (late pregnancy*), 6 (6‐11*) months postpartum abstinence, and > 50% reduction in cotinine* from baseline to late pregnancy interview. | |
| Notes | Guide developed through needs assessment with pregnant women, constructs from the PRECEDE/PROCEED diagnosis and social learning theory, tested with focus groups, additional section on relapse prevention, and on passive smoking postpartum. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | No information provided. |
| Allocation concealment (selection bias) | Unclear risk | Described as "randomly assigned". |
| Incomplete outcome data (attrition bias) | Unclear risk | 16.3% attrition due to miscarriage, termination and change of care provider (C = 37, I = 34). 145/391 (37%) remaining women did not provide saliva samples and were treated as smokers in the analysis but those lost to follow‐up for other reasons were excluded from the analysis in reports and in this review. 6* months postpartum abstinence was collected and only small sample of 6‐month data reported (C = 48, I = 46), however all missing data included as continuing smokers in this review. |
| Selective reporting (reporting bias) | High risk | Three month postpartum outcomes not reported and minimal follow‐up for 6‐month postpartum data. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Self‐report of 'not even a puff in past 7 days' biochemically validated by salivary cotinine < 30 ng/mL. |
| Blinding of participants and personnel (performance bias) | High risk | Educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | Process evaluation showing good implementation. |
| Equal baseline characteristics in study arms | Unclear risk | Women in control group reported significantly fewer cigarettes per day and more likely to be African‐American. |
| Contamination of control group | High risk | Same care providers delivering intervention who were providing care to control group. |
| Methods | This 3‐armed randomised controlled trial, of voucher distribution aimed to investigate if pregnant indigenous NZ women who smoke, were more likely to abstain from smoking if given products or vouchers. This study was conducted amongst self‐identified Maori women in Auckland, New Zealand with recruitment occurring between December 2012 and June 2013. | |
| Participants | Inclusion criteria: > 16 years, self‐identified as Maori, residing in the Auckland region, are 2‐30 weeks pregnant and are daily smokers. Exclusion criteria: If they were no longer smoking daily or if they were participating in any other smoking trials. Recruitment: Only 32% (24/74) participation rate, (A = 8 B = 8 C = 8) Women were identified through independent midwives, GP clinics, the district health board, maternity services, a Facebook page, pamphlets and flyers, radio and newspaper articles. Baseline characteristics: Mean cigarettes per day‐ 9, First cigarette within 5 mins of waking up ‐ 46%, Mean Age‐ 25 years, Single (A = 38%, B = 38%, C = 25%) Progress + coding: Low SES | |
| Interventions | A: Control: A less intensive intervention, where participants were provided with cessation support, including information about different cessation products and services. In addition, the research assistant was a trained Quit Card (for accessing heavily subsidised NRT) provider. B: Intervention 1: For the voucher condition participants were provided with a $25 voucher from Farmers Trading Company, a general department store with branches throughout NZ that does not stock artificial infant food, alcohol or cigarettes. C: Intervention 2: Product participants were able to choose from 24 different products packs. If they were abstinent for all 8 weeks they were eligible to receive products to the value of NZ$200 Main Intervention Strategy: Smoking Cessation Intervention: Incentives (single) v Less intensive intervention. Arms A and B are compared in this study ID. Intensity: Frequency (C = 6 I = 6) Duration (C = 1 I = 4) | |
| Outcomes | Continuous (weekly) biochemically validated abstinence for 8 weeks in late pregnancy* (exhaled CO < 7 ppm), mean weekly self‐reported smoking status. | |
| Notes | This was a feasibility study and many of the variables were regarding the women's financial situation and use of cessation products and services during the intervention. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Immediately after baseline data had been recorded, participants were randomised in a 1:1 ratio to 1 of 3 arms using envelope randomisation prepared by a statistician |
| Allocation concealment (selection bias) | Unclear risk | Not clear whether the envelope used for randomisation was opaque. |
| Incomplete outcome data (attrition bias) | Low risk | Dropouts were assumed to have relapsed back to smoking. |
| Selective reporting (reporting bias) | Low risk | All outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking was biochemically validated, participants were considered to be smokers if they reported smoking during the previous week or if they had a CO measure < 7 ppm for 1 month. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Unclear, as the research assistant collecting outcome data and research administrator were not blinded to treatment allocation. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Participants and the research assistant (RA) collecting the outcome data and research administrator were not blinded to treatment allocation, but the researchers analysing the data were. |
| Incomplete implementation | High risk | Only 37.5% retention rate. |
| Equal baseline characteristics in study arms | Low risk | Baseline characteristics seemed equal in all 3 study arms. |
| Contamination of control group | Low risk | Main intervention strategies were provision of vouchers. |
| Methods | This 3‐armed randomised controlled trial, of voucher distribution aimed to investigate if pregnant indigenous NZ women who smoke, were more likely to abstain from smoking if given products or vouchers. This study was conducted amongst self‐identified Maori women in Auckland, New Zealand with recruitment occurring between December 2012 and June 2013. | |
| Participants | Inclusion criteria: > 16 years, self‐identified as Maori, residing in the Auckland region, are 2‐30 weeks pregnant and were daily smokers. Exclusion criteria: If they were no longer smoking daily or if they were participating in any other smoking trials. Recruitment: Only 32% (24/74) participation rate, (A = 8 B = 8 C = 8) Women were identified through independent midwives, GP clinics, the district health board, maternity services, a Facebook page, pamphlets and flyers, radio and newspaper articles. Baseline characteristics: Mean cigarettes per day‐ 9, First cigarette within 5 mins of waking up‐ 46%, Mean Age ‐ 25 years, Single (A = 38%, B = 38%, C = 25%). Progress + coding: Low SES. | |
| Interventions | A: Control:A less intensive intervention, where participants were provided with cessation support, including information about different cessation products and services. In addition, the research assistant was a trained Quit Card (for accessing heavily subsidised NRT) provider. B: Intervention 1: For the voucher condition participants were provided with a $25 voucher from Farmers Trading Company, a general department store with branches throughout NZ that does not stock artificial infant food, alcohol or cigarettes. C: Intervention 2: Product participants were able to choose from 24 different products packs. If they were abstinent for all 8 weeks they were eligible to receive products to the value of NZ$200 Main Intervention Strategy: Smoking Cessation Intervention: Incentives (single) v Less intensive intervention. Arms A and C are compared in this study ID. Intensity: Frequency (C = 6 I = 6) Duration (C = 1 I = 4). | |
| Outcomes | Mean weekly self‐reported smoking status, Continuous biochemically validated abstinence for 8 weeks* | |
| Notes | This was a feasibility study and many of the variables were regarding the women's financial situation and use of cessation products and services during the intervention. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Immediately after baseline data had been recorded, participants were randomised in a 1:1 ratio to 1 of 3 arms using envelope randomisation prepared by a statistician |
| Allocation concealment (selection bias) | Unclear risk | Not clear whether the envelope used for randomisation was opaque. |
| Incomplete outcome data (attrition bias) | Low risk | Dropouts were assumed to have relapsed back to smoking. |
| Selective reporting (reporting bias) | Low risk | All outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking was biochemically validated, participants were considered to be smokers if they reported smoking during the previous week or if they had a CO measure < 7 ppm for 1 month. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Unclear, as the research assistant collecting outcome data and research administrator were not blinded to treatment allocation. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Participants and the research assistant (RA) collecting the outcome data and research administrator were not blinded to treatment allocation, but the researchers analysing the data were. |
| Incomplete implementation | High risk | Only 37.5% retention rate. |
| Equal baseline characteristics in study arms | Low risk | Baseline characteristics seemed equal in all 3 study arms. |
| Contamination of control group | Low risk | Main intervention strategies were provision of vouchers. |
| Methods | This randomised controlled trial aimed to measure the effectiveness of home‐based visiting from trained lay‐persons to reduce LBW. The study was conducted in the prenatal clinic of a university hospital in Cleveland, USA, from March 1987 to September 1989. | |
| Participants | Inclusion criteria: Living within 5‐mile radius of clinic, 17‐28 weeks' gestation, ‘low’ family function rating, at least 1 stressful life event during pregnancy, and additional risk factors such as smoking, low maternal weight‐height ratio, aged over 27 years, or history of a previous premature baby. Exclusion criteria: White patients, difficulty reading English. Recruitment: Every person registering at clinic was eligible to be screened. The first 105 screened participants were dropped from the study when it was found that they had difficulty reading the questions. 1326 women screened. 1022 ‘low risk, 190 ‘high risk’ women – of which 145 were randomised (I = 87, C = 58). 8.5% of low risk and 15% high risk women were smokers. Baseline characteristics: Smoking characteristics not reported. Predominantly black, poor, inner city population. No progress plus coding as outcomes not able to be included in this review. | |
| Interventions | Control: Routine care from obstetrical staff in the clinic. Intervention: 2 non‐professional black women who demonstrated rapport with women served as home‐visitors and were trained in childbirth education, community resources, and nutrition during pregnancy. 4 x 1 hour home visits occurred at 4‐6 week intervals. The home visitors followed a protocol which included psychosocial support, efforts at stress reduction, information on health risks (especially smoking and drinking), nutrition education, and a small gift. Main intervention strategy: Not coded as outcomes not included in this review. Provided by study staff: efficacy study. | |
| Outcomes | Smoking outcomes were not able to be included in this review as it is unclear how many smokers were included in each study arm. LBW was the primary outcome for this study, but was not included in this review, as aspects other than the smoking component of the intervention may have had an effect on birthweight. See Table 2 for summary of outcomes not able to be included in this meta‐analysis. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Table of random numbers. |
| Allocation concealment (selection bias) | Unclear risk | Not stated. |
| Incomplete outcome data (attrition bias) | High risk | 24/87 dropped out and unclear if included in analysis. 7 refused intervention, 11 could not be contacted, 5 transferred care, 1 miscarried prior to visit. Numbers reported as randomised different in abstract (154) and flow chart (145). |
| Selective reporting (reporting bias) | Unclear risk | Unclear if selective reporting as smoking cessation was not the primary aim of the intervention. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Not applicable. Smoking outcomes not reported. |
| Blinding of participants and personnel (performance bias) | High risk | Women and home visitors not blinded, as would be expected in an educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Process evaluation showed only 63/87 women received home visits |
| Equal baseline characteristics in study arms | Unclear risk | Not reported. |
| Contamination of control group | Low risk | Home visiting intervention so risk contamination of control group is low. |
| Methods | Randomised controlled trial of providing feedback on cotinine to support women to stop smoking in pregnancy and reduce LBW. Study conducted in physicians offices and clinic sites within Maine (USA) from 1984 to 1987. | |
| Participants | Inclusion criteria: Pregnant women with a singleton live pregnancy; having maternal serum AFP screening at 15‐20 weeks' gestation; who smoked >= 10 cigarettes a day. Exclusion criteria: Not further specified. Recruitment: Physicians approached (no consent from women). 25,628 women completed maternal serum screening form, 97% answered question on smoking and 17% smoked >= 10 cigarettes/day. 2848 women were randomised (C = 1425, I = 1423). Baseline characteristics:Mean cigarettes/day at baseline: C = 16.3, I = 16.1 Maternal education (mean years): C = 11.8, I = 11.9. Progress + coding: None. | |
| Interventions | Control: Standard medical care not otherwise specified. Main intervention strategy: Feedback (multiple intervention) compared to UC. Intensity: Frequency (C = 0, I = 3), Duration (C = 0, I = 2). UC intensity: F = 0, I = 0. Intervention provided by existing staff: Effectiveness study. | |
| Outcomes | No smoking cessation data. Smoking data limited to comparability at first assessment and mean serum cotinine levels, which could not be included as they are disaggregated by low and high study site participation. Mean birthweight*; low* and very low* birthweight; preterm birth* (< 37 weeks); stillbirths (> 20 weeks)*; neonatal deaths*; postneonatal deaths. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer‐generated random numbers. |
| Allocation concealment (selection bias) | Unclear risk | Information not provided. |
| Incomplete outcome data (attrition bias) | High risk | 2700/2848 (94.8%) included in analysis. 3% lost to follow‐up and 2% multiple gestations or fetal deaths. Only 695/1343 (48%) women in the intervention groups provided repeat serum cotinine for comparison. No ITT analysis. No smoking outcomes reported and unable to re‐include data for mean cotinine and birth outcomes. |
| Selective reporting (reporting bias) | High risk | Results difficult to interpret. Smoking cessation not recorded. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Serum cotinine measurement at baseline for both the experimental and comparison groups but it was not clear that any follow‐up measurements were made for the comparison group. |
| Blinding of participants and personnel (performance bias) | High risk | Caregivers aware of group allocation. Experimental group given feedback on serum cotinine levels. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Process evaluation showed less than good implementation with differential impact on perinatal outcome by completeness with second blood samples taken for cotinine measurement. |
| Equal baseline characteristics in study arms | Low risk | Intervention groups similar at trial entry. |
| Contamination of control group | Low risk | Intervention not provided by care provider. |
| Methods | Cluster‐randomised controlled trial of a brief midwife‐delivered intervention to support women to stop smoking in pregnancy. Study conducted in 9 hospital and community trusts in the UK. Years of data collection not reported. | |
| Participants | 290 midwives randomised to provide intervention or control care. Inclusion criteria:Pregnant women currently smoking or stopped within the last 3 months. Exclusion criteria: Not further specified. Recruitment: Women were recruited at first visit (approximately 12 weeks' gestation). Estimated 8700 eligible women. Only 178/290 (61%) midwives (C = 86, I = 92) recruited any women. Financial incentives were paid to boost recruitment. 1287 women provided informed consent. Baseline characteristics: Current smokers (C = 440, I = 441); Spontaneous quitters (C = 135, I = 114). 189 current smokers were assessed as 'not motivated to stop' therefore received no intervention. Mean cigarettes/day: Smokers (C = 9.7, I = 10.1), Ex‐smokers (C = 10.9, I = 12.6). > 70% married, 26%‐27% smokers and 10%‐15% ex‐smokers had no educational qualifications. Progress + coding: None. | |
| Interventions | Control: Midwives received 1 hour of training to discuss the study and were asked to provide UC and any usual pamphlets. Intervention: Midwives received 2 hours training which included using the CO monitor and providing 'stage of change' based advice, CO assessments. Intervention group also received written advice and motivational materials for current and recent smokers, including designating a 'quit date', a 'quiz' and the offer of 'buddying' to another pregnant smoker for support. Main intervention strategy: Counselling (tailored) compared to UC. Intensity: Frequency (C = 0, I = 5), Duration (C = 0, I = 2). Intervention provided by routine midwives: Effectiveness study. | |
| Outcomes | Biochemically validated point prevalence abstinence at birth (late pregnancy*), relapse prevention*, and self‐reported continuous abstinence at 6 (6‐11) months postpartum among baseline smokers* and spontaneous quitters. Participants and midwives views of interventions reviewed. | |
| Notes | Clustering effect not reported, so sensitivity analysis conducted using 4 ICCs and outcome figures adjusted using conservative intracluster correlation of 0.1. Discussion of barriers includes 65% of midwives reporting the intervention could not be undertaken in the time they had available. Sample size justification. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Cluster‐randomisation of midwives adequate. Consecutive names on a list of midwives. |
| Allocation concealment (selection bias) | Unclear risk | Midwives randomised. |
| Incomplete outcome data (attrition bias) | Unclear risk | 167/1287 (12.9%) (C = 83, I = 84) excluded from analysis due to moving away, being untraceable or deemed unsuitable for follow‐up (e.g. miscarriage). 1120 in sample. 51/1287 non‐responders were included as continuing smokers. |
| Selective reporting (reporting bias) | Unclear risk | Unclear if all outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation by expired CO < 10 ppm. |
| Blinding of participants and personnel (performance bias) | High risk | Midwives aware of allocation group. Educational intervention. Blinding women not feasible. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Blinding of outcome assessment not reported. Not blinded if performed by midwives. |
| Incomplete implementation | High risk | Process evaluation showed poor implementation in some areas. |
| Equal baseline characteristics in study arms | High risk | Control group slightly more interested in quitting smoking and less nicotine dependent. |
| Contamination of control group | Low risk | Cluster trial design to minimise risk of contamination. |
| Methods | A 2‐armed single randomised controlled trial of a web‐based contingency management program; Motiv8. This study was conducted in Rural Appalachia, Ohio and Kentucky on a community sample of pregnant smokers, recruited from prenatal clinics. | |
| Participants | Inclusion criteria: Adults aged 18 years and older, daily smokers (reporting smoking at least 2 cigarettes per day verified by breath CO readings and urinary cotinine levels), and were <= 12 weeks pregnant Exclusion criteria: Not stated. Recruitment: 47% participation rate (C = 10 I = 7). Baseline characteristics: Nicotine dependence (modified Fagerstroms test) (C = 4.90 I = 5.71), Cigarettes per day (C = 13.69 I = 9.45) Mean Age (C = 24.20 I = 24.00). Progress + coding: Low SES. | |
| Interventions | Control: Intensive phone delivered cessation counselling program based on Smoking Cessation for Healthy Births (SCHB). Intervention: The Motiv8 program lasted 6 weeks and consisted of 5 phases: Baseline (7 days), Shaping (4 days), Abstinence (21 days), Thinning (5 days), and Return to Baseline (5 days). During each phase, participants submitted video recordings of themselves twice per day (at least 8 hours apart) giving breath samples using the Smokerlyzer. They could earn vouchers exchangeable for online purchases with major retailers (e.g. Best Buy, Wal‐Mart) for criterion breath samples based on program phase. For the Abstinence phase, participants were required to have breath CO levels <= 4 ppm. Main Intervention strategy: Incentives (single) v alternative Intervention Intensity: Frequency (C = 4, I = 6) Duration (C = 4, I = 4). Intervention provided by study staff: efficacy study | |
| Outcomes | Biochemically validated smoking abstinence in late pregnancy*, Smoking reduction by 50% urine cotinine levels* | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Reporting smoking at least 2 cigarettes per day verified by breath CO readings and urinary cotinine levels |
| Allocation concealment (selection bias) | Low risk | As randomisation was done by computer, allocation of participant to control or intervention would have been concealed. |
| Incomplete outcome data (attrition bias) | Low risk | Any missing data were coded as non abstinent/reduction. |
| Selective reporting (reporting bias) | Low risk | All outcomes are reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking was biochemically validated by breath CO levels <= 4 ppm and urinary cotinine levels. |
| Blinding of participants and personnel (performance bias) | High risk | Blinding did not seem to occur as physician and participant would know which arm of the trial they were in. |
| Blinding of outcome assessment (detection bias) | Unclear risk | This was not described. |
| Incomplete implementation | High risk | Only 68% of intervention participants provided the required breath samples at follow‐up and in control, phone counsellors provided on average 3.9 of the required 5 phone calls. |
| Equal baseline characteristics in study arms | Low risk | Baseline characteristics in both arms appear equal. |
| Contamination of control group | Low risk | Intervention and control were either delivered via the web or mobile phone so contamination very unlikely. |
| Methods | Randomised controlled trial of self‐help materials and health education to support women to stop smoking in pregnancy. Study conducted in a teaching hospital (academic) clinic in North Carolina, USA from August 1991 to January 1993. | |
| Participants | Inclusion criteria: Pregnant women who smoke. Exclusion criteria: > 36 weeks' gestation, psychiatric diagnosis. Recruitment: 842/846 (99%) women attending the clinic completed survey and 793/846 provided a CO breath sample.; 2 were excluded as > 36 weeks' gestation; 1 for psychiatric diagnosis; leaving 266 (32%) eligible smokers (smoked at least once in the prior week). 12 refused, 4 were missed, 2 were not pregnant and 1 was a private patient. 247 women randomised. Baseline characteristics: Mean cigarettes/day (C = 14.4, I = 13.5), Want to quit (C = 81%, I = 84%). Smokers in household (C = 75%, I = 78%). White (C = 74%, I = 78%), Single (C = 44%, I = 47%), < 12 yrs education (C = 43%, I = 48%). Progress + coding: Low SES. | |
| Interventions | All 1‐ to 4‐year residents given didactic and role play training for smoking cessation counselling, including self‐assessment of current techniques and skills, which they were asked to continue with for the control group. Main intervention strategy: Counselling (multiple intervention) compared to UC. Intensity: Frequency (C = 0, I = 6), Duration (C = 0, I = 2). UC intensity: F = 1, D = 1. Intervention provided by existing staff: Effectiveness study. | |
| Outcomes | Biochemically validated abstinence at last prenatal visit (late pregnancy*). > 50% reduction in self‐reported smoking*, mean cigarettes per day*. Cost‐effectiveness data reported. | |
| Notes | SDs for mean cigarettes per day were not reported, therefore we calculated a mean SD from 14 studies with available mean cigarette SDs (6.5) to include in this review, as recommended by the cochrane handbook | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer‐generated random numbers. |
| Allocation concealment (selection bias) | High risk | State that neither the enrolling nurse nor the patient were aware of allocation, but experimental group notes were flagged. |
| Incomplete outcome data (attrition bias) | High risk | Attrition 40/247 (16%) (4 miscarriages first trimester, 3 miscarriages second trimester, 3 terminations, 15 moved to alternative care, and 12 lost to follow‐up) 207 included in analysis (C = 100, I = 107). Those lost to follow‐up not able to be re‐included in analysis in this review as numbers not reported by study arm. |
| Selective reporting (reporting bias) | Unclear risk | Not apparent. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Exhaled CO measured at each visit for the experimental group and at 3 visits for the comparison group. < 5 ppm counted as non‐smokers. |
| Blinding of participants and personnel (performance bias) | High risk | Case notes flagged. States patient not aware of randomisation status. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | No process evaluation reported. |
| Equal baseline characteristics in study arms | Low risk | No significant differences noted. |
| Contamination of control group | High risk | Concerns about residents having to treat similar/consecutive patients differently, and self‐help manuals accidentally given to some controls. Discussion section reports evidence of contamination with self‐help materials being given to controls. |
| Methods | Cluster‐randomised controlled trial of brief GP counselling to support women to stop smoking in pregnancy and prevent relapse postpartum. Study conducted in Western Norway from November 1986 to November 1987. | |
| Participants | Inclusion criteria: No indications of serious social or medical problems, living with a partner, and smoking at least 5 cigarettes per day before pregnancy and still smoking at least 1 cigarette per day at the first checkup. Exclusion criteria: Not further specified. Recruitment: All 398 GPs in western Norway were invited by mail to participate in the study. 187 participating GPs were asked to recruit 4 pregnant and 4 non‐pregnant women for the study, at the first checkup in the first trimester. 1/3 pregnant and non‐pregnant women ended up in control groups. The GPs who recruited pregnant women for the intervention groups recruited non‐pregnant women for the control groups. 2379 pregnant women screened, 674 fulfilled inclusion criteria, 144 refused to participate (21%). 530 pregnant women were randomised (unclear how many each group). Baseline characteristics:Mean age starting smoking 27.6, mean cigarettes per day = 9.5. Mean age 25.9. 18‐34 years of age, all living with a partner. Progress + coding: None. | |
| Interventions | Control: Ordinary control programme during pregnancy and for first year after delivery (UC). Intervention: (i) < 15 mins GP consultation at initial visit about hazards of smoking, how to stop and how to avoid relapse; (ii) information about problems related to 'the smoking fetus'; (iii) delivered with aid of a 5‐page 'flip‐over'; (iv) 8‐page booklet. Women invited to consult their GPs after 1, 6, 12 and 18 months to discuss their smoking habits. Main intervention strategy: Counselling (multiple intervention) compared with UC. Intensity: Frequency (C = 0, I = 3), Duration (C = 0, I = 1). UC intensity: F = 0, D = 0. Intervention provided by existing staff (GPs): Effectiveness study. | |
| Outcomes | Self‐reported abstinence 6 months after study entry (late pregnancy*), biochemically validated at 12 months after study entry (0‐5 months postpartum*), self‐reported abstinence 15 (6‐11 months postpartum*) and 18 months after study entry (12‐17 months postpartum*). Self‐reported reduction and increase in smoking. Mean cigarettes/day and mean thiocyanate (not included as only reported by smoking status at 18 months postpartum). An associated reference (Haug 1992) reports results of a survey of GPs delivering the intervention. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | GPs described as randomly allocated. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | High risk | 180/530 dropped out due to spontaneous abortions (24), serious complications (8), moved to another district (31) or for other unknown reasons (117). Only 350/530 (C = 98, I = 252) included in analysis and we were unable to re‐include those lost to follow‐up for other reasons in this review as they were not reported by group allocation. Further dropouts not explained (C = 97 and I = 244 in outcome tables‐re‐included in this review as continuing smokers). |
| Selective reporting (reporting bias) | Unclear risk | Not clear if biochemically validated outcomes reported. |
| Other bias | High risk | Unequal recruitment to study arms (higher recruitment in intervention arms). |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Biochemical validation of smoking only at study entry and after 12 months (urinary thiocaynate). Unclear if those who had high thiocaynate levels were considered smokers. No cut‐off levels reported. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel to counselling intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | 59% residents did not document consultation. 1 component dropped. |
| Equal baseline characteristics in study arms | Unclear risk | Not reported. |
| Contamination of control group | High risk | Same providers asked to provide control and intervention arms for pregnant and non‐pregnant women. |
| Methods | Randomised controlled trial of motivational enhancement therapy to support women to stop smoking in pregnancy. Dates of research and location not stated. Assume USA from author affiliations. | |
| Participants | Inclusion criteria: Opioid‐dependent women, <= 26 weeks' gestation, receiving methadone, currently smoking at least 5 cigarettes per day, enrolled in hospital prenatal program. Exclusion criteria: Not further specified. Recruitment: During first 48 hours of 7‐day residential program. 77 women randomised. 14 women excluded from analysis due to miscarriage, abortion, premature delivery and miscalculated gestational age. 63 included in analysis (I = 30, C = 33). Baseline characteristics: Mean cigarettes per day 19.9 (SD 11.5). Approximately 50% had lifetime major depressive disorder, 32% were depressed in last month, and 39% had anxiety disorder. 84% African American, 79% single, 97% unemployed. 94% had less than high school education. Not coded for equity analysis as outcomes not able to be included in this review. | |
| Interventions | Control: Health practitioner advice by trained research staff and printed materials from American Lung Association and American Cancer Society. Intervention: As control + Motivational Enhancement therapy using ‘Project MATCH’ manual with modifications for nicotine dependence, provided over 4 sessions by masters level research associates. Main strategy and intensity not coded as outcomes unable to be included in meta‐analysis. | |
| Outcomes | Mean cigarettes per day, mean exhaled CO, mean cotinine, movement in stages of change were collected and authors report that there was no significant difference. However, not actual figures were provided to be able to include these outcomes in meta‐analysis in this review. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Just states participants were 'randomly assigned' to 1 of 2 conditions. |
| Allocation concealment (selection bias) | Unclear risk | Not stated |
| Incomplete outcome data (attrition bias) | High risk | Participant attrition was 14% (n = 9). Final figures not reported so unclear how many included in analysis. |
| Selective reporting (reporting bias) | Unclear risk | Actual smoking rates not reported, despite this being a primary outcome for the study. However, authors did not claim results were significant. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Cotinine and CO validation measured, but not reported. |
| Blinding of participants and personnel (performance bias) | High risk | Intervention providers and women not blinded as counselling intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not stated. |
| Incomplete implementation | Unclear risk | Process evaluation not reported. |
| Equal baseline characteristics in study arms | Unclear risk | Intervention group had lower mean education levels, were more likely to be Caucasian, and had higher rates of pre‐pregnancy cigarettes per day. Other factors equal. |
| Contamination of control group | Low risk | Masters level research associates provided the intervention. |
| Methods | Quasi‐randomised trial of counselling and optional NRT, to support women to stop smoking in pregnancy. Study conducted in a large midwifery centre in the Netherlands, with data collection from 1996 to 1998. | |
| Participants | Inclusion criteria: All pregnant women attending first prenatal visit. Exclusion criteria: Inability to speak Danish, age below 18 years, gestation of more than 22 weeks, verified psychiatric diseases, and alcohol or drug abuse. Recruitment: 696/905 (77%) eligible women attending first AN clinic who smoked agreed to participate in study (informed consent) and were randomised (C = 347, I = 348). 647 included in final analysis (C = 320, I = 327). Baseline characteristics: Mean cigarettes/day = 11, Significant difference in partner smoking (I = 67%, C = 77%, P = 0.03), mean salivary cotinine (C = 141, I = 139). Mean age 29 yrs, > 12 yrs in school (C = 45%, I = 43%), mostly married. Progress + coding: None. | |
| Interventions | Control: UC, which included routine information about the risk of smoking in pregnancy and general advice on smoking cessation or reduction in a standard 30‐min consultation. Intervention: (i) Extended initial consultation (from 30 to 40 mins) which included a dialogue about smoking and motivation for cessation. (ii) written information about risks of smoking and passive smoking. (iii) invitation to join smoking cessation program, based on CBT. The program involved 9 appointments (individually or in a group) over a period of 14 weeks. 3 attendances prepared participants for quitting and 6 were used to maintain cessation and to hand out NRT. CO readings at each visit. (iv) NRT offered to all women (2 mg gum or 15 mg patch x 16 h) for 11 weeks. (v) encouragement at subsequent 5‐6 AN visits. Main intervention strategy: Counselling (tailored) compared with UC. Intensity: Frequency (C = 0, I = 6), Duration (C = 0, I = 6). UC intensity: F = 1, D = 1. Intervention provided by specially trained midwife (study staff): Efficacy study. | |
| Outcomes | Biochemically validated smoking cessation at 37 weeks' gestation (late pregnancy*), mean birthweight*, LBW*. Preterm births* reported in attrition and re‐included in both numerator and denominator for this outcome. Regression analysis for passive smoke exposure, years of education reported. | |
| Notes | SDs for mean birthweight were not reported, therefore we calculated a mean SD from 13 studies with available birthweight SDs (578) to include in this review, as recommended by the cochrane handbook | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | High risk | Quasi‐randomised by odd or even birth date. Included in review despite inadequate sequence generation as there is a low likelihood of interference with birth date allocation. |
| Allocation concealment (selection bias) | High risk | Quasi‐randomised by odd or even birth date. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition: 10 had miscarriage or stillbirth (C = 5, I = 5); 21 moved out of area (C = 12, I = 9); 17 had a premature delivery (C = 10, I = 7). These were excluded from analysis. |
| Selective reporting (reporting bias) | Low risk | Primary outcomes appear to be reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking cessation validated by salivary cotinine <= 30 ng/mL. |
| Blinding of participants and personnel (performance bias) | High risk | Providers and participants not able to be blinded to educational intervention and NRT provision not blinded (no placebo). |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not stated. |
| Incomplete implementation | High risk | Only 87 women (27%) accepted participation: 81 in a group and 6 women accepted an individual smoking cessation program. 71 of 87 participants (82%) participated in 3 or more of a total of 9 meetings in the smoking cessation program. 75 (86%) of 87 women participating in the smoking cessation program were using nicotine substitution in the form of a 15 mg nicotine patch (16 h/day) or 2 mg nicotine chewing gum or a 15 mg nicotine patch (16 h/day) plus 2 mg nicotine chewing gum. |
| Equal baseline characteristics in study arms | Unclear risk | Mostly equal except more women were exposed to passive smoking in the home in the intervention group (77%) than in the control group (67%) (P = 0.03). |
| Contamination of control group | Unclear risk | The strengths of the study include absence of treatment diffusion as all participants in the intervention group were seen by specially trained midwives as opposed to participants in the control group who were all consulting midwives without such training. The study enjoys a second advantage which is that intervention and control group participants were seen at different week days and hence could not easily share information. |
| Methods | Randomised controlled trial of financial incentives to support women to stop smoking in pregnancy and prevent relapse postpartum. Study conducted in Greater Burlington, Vermont (USA) with data collection from 2001 to 2003. | |
| Participants | Inclusion criteria: Self‐reported smoking (even a puff in the last 7 days), gestational age less than 20 weeks, living within study clinic county and not planning to move until at least 6 months postpartum, and speaks English. Exclusion criteria: Incarceration or previous participation in the study or living with anyone who has previously participated in the study. Recruitment: Participants were recruited from 1 of 4 large obstetric practices in the Women, Infants and Children (WIC) program. 182 women were eligible for the study, and 82 (45%) agreed to participate. Mean gestation at recruitment (I = 8.9, C = 9.5). 77 included in analysis (C = 40, I = 37). Baseline characteristics: Pre‐pregnancy cigarettes per day (I = 18.7, C = 18.4), Health insurance (I = 19%, C = 13%). Progress + coding: Low SES as WIC program recipients. | |
| Interventions | Control (non‐contingent voucher): Participants received voucher independent of smoking status. US$ 15.00 per AN visit and US$ 20.00 per postpartum visit, to result in comparable average earnings to the contingent group. Both groups received routine advice from the clinic. Intervention (contingent voucher): participants chose a quit date, and reported daily to the clinic for CO monitoring for 5 days, then urine cotinine monitoring twice weekly for 7 weeks, weekly for 4 weeks, and then every 2 weeks for the remainder of the pregnancy. Vouchers were given dependent on biochemical validation, beginning at US$ 6.25 and escalated by US$ 1.25 to a maximum of US$ 45.00. Positive test results reset voucher back to original value, but 2 consecutive negative tests restored value to pre‐reset value. It is unclear who delivered the intervention. Main intervention strategy: Incentives (single intervention) compared to alternative intervention. Intensity: Frequency (C = 6, I = 6), Duration (C = 6, I = 6). Intervention provided by study staff: efficacy study. | |
| Outcomes | Biochemically validated smoking cessation (7‐day point prevalence) at >= 28 weeks' gestation (late pregnancy*), 12 weeks (0‐5 months*) and 24 weeks' (6‐11 months*) postpartum. Reduction in mean cotinine. Mean birthweight*, gestational age, fetal growth measures (US), and proportion of NICU admissions, LBW* infants, and preterm births*. Nicotine withdrawal symptoms reported in associated reference (Heil 2004). | |
| Notes | Sample size justification. Some discussion of cost implications. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as "randomisation stratified to clinics". Details of randomisation not described. |
| Allocation concealment (selection bias) | Unclear risk | No information. |
| Incomplete outcome data (attrition bias) | Unclear risk | 5 women withdrew from the study due to fetal demise or termination of pregnancy and were not included in the final analysis (I = 3, C = 2). |
| Selective reporting (reporting bias) | Low risk | Detailed birth outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation using exhaled CO for 5 days (< 6 ppm) and then urine cotinine (< 80 ng/mL) after 2 weeks. |
| Blinding of participants and personnel (performance bias) | High risk | Participants and providers not blinded as receiving incentives for participation. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | Compliance with periodic assessments was relatively high (83%–95%). |
| Equal baseline characteristics in study arms | Low risk | No significant differences in socio‐demographics or smoking characteristics were noted. |
| Contamination of control group | Low risk | Very unlikely ‐ as clear voucher schemes for abstinence and non‐abstinence. |
| Methods | Randomised controlled trial of mobilising peer social networks to support pregnant women to stop smoking. The study was conducted in urban Women, Infants and Children (WIC) clinics in Minnesota and an urban university outpatient obstetric clinic in Ohio, USA from 2005 to 2007. | |
| Participants | Inclusion criteria: Pregnant women in the first or second trimester, a current smoker, and at least 18 years old. Exclusion criteria: Not further specified. Recruitment: Each eligible and consenting participant identified a woman in her social network to act as a supporter. 872 women screened in waiting areas. 82/156 (53%) eligible women and their supporters agreed to participate (C = 28, I = 54). Baseline characteristics: Median number of cigarettes smoked per day = 5 (range = 1‐25) and 52% smoked their first cigarette within 30 min of waking. 52% of supporters were current smokers and 22% were former smokers. There were no significant differences between study arms. 67% from racial minority groups, 65% had high school education or less. Median age = 24. Progress + coding: Low SES as all WIC program recipients; ethnic minority. | |
| Interventions | Control: 1 in‐person counselling session for control and intervention participants designed to increase motivation to quit and provide information about community smoking cessation resources. Intervention: Peer‐supporters in the intervention group had 1 in‐person visit and monthly telephone sessions. The primary goal was to develop strategies to help the participant quit smoking by identifying specific activities to support efforts to quit. Women and their supporters were given a pregnancy scrapbook that included pages related to smoking cessation tasks. Main intervention strategy: Social support (single intervention) compared to a less intensive intervention. Intensity: Frequency (C = 2, I = 4), Duration (C = 2, I = 5‐ estimated). Intervention provided by specific staff: Efficacy study. | |
| Outcomes | Biochemically validated smoking status just prior to expected delivery date (late pregnancy*) and 3 (0‐5*) months postpartum. Women's perceptions of peer support behaviours reported (both positive and negative). | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Blocked random allocation sequence |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | Attrition: C = 25%, I = 11% by end of pregnancy. C = 19%, I = 32% by 3 months postpartum. Report ITT analysis for end of pregnancy validated quits. 7 women who had miscarriages were excluded from the analysis. All randomised participants included in the analysis in this review (dropouts included as continuing smokers). |
| Selective reporting (reporting bias) | Low risk | All primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Self‐reported smoking status biochemically validated using urinary cotinine (< 100 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and providers to this social support intervention. |
| Blinding of outcome assessment (detection bias) | Low risk | Outcome assessors blinded as 'evaluation staff were blinded to group assignment'. |
| Incomplete implementation | High risk | Process evaluation showed over 90% supporters received at least 1 counselling session, but contacts with supporters occurred less frequently than the planned monthly intervals because of difficulty reaching supporters. |
| Equal baseline characteristics in study arms | Unclear risk | Significantly more intervention participants had other children (78% vs 57%, P = 0.052) and significantly fewer were white (22% vs 54%, P = 0.016), but other characteristics equal. |
| Contamination of control group | Low risk | Contamination unlikely with this intervention which required researchers to contact intervention group at home. |
| Methods | This 2‐armed randomised controlled trial aimed to assess the effectiveness of 'MumsQuit' an Internet‐based smoking cessation website. The study was conducted in the UK between March 2012 and October 2013. | |
| Participants | Inclusion criteria:Pregnant women with access to the Internet, aged 18 or more, UK based, smoking daily, willing to make a serious quit attempt, and use a stop smoking website which sends email reminders, as well as agree to be followed up over the telephone at 2 months, and provide informed consent. Exclusion criteria: Being male or not being pregnant. Recruitment:200/336 = 59.5% eligible women participated (C = 101 I = 99). Baseline characteristics: Mean cigarettes per day 14.7, Mean age of smoking initiation, 15.9 years, Mean Age 27.87 years. Appalachian women have a lower than average SES and lower levels of education. Progress + coding: Low SES | |
| Interventions | Control: The control condition involved a 1 page static, non personalised website that provided brief standard advice for users. The content of the control website was based on a widely used manual for smoking cessation support for practitioners Intervention: MumsQuit offers an interactive, personalised, and structured quit plan that emulates the support from an expert smoking cessation advisor from NHS Stop Smoking Services. The intervention delivers 33 evidence‐ or theory‐based behavior change techniques and provides up to 4 weeks of pre quit date support and up to 4 weeks of post quit date support, with email reminders sent to notify users when new intervention sessions are being released. Main Intervention strategy: Health Education (single) v Less intensive intervention. Intensity: Frequency (C = 2 I = 4) Duration (C = 1 I = 2). | |
| Outcomes | Self‐reported continuous 4‐week abstinence assessed at 8 weeks post‐baseline*. | |
| Notes | Also a process evaluation, lots of outcomes regarding amount of logins and time spent on each page of the website. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | After consenting, participants were randomised by the computer to receive access to either MumsQuit or the control condition, with allocation concealment and locking of emails to minimize duplicate sign ups. |
| Allocation concealment (selection bias) | Low risk | Participants were randomised by the computer to receive access to either MumsQuit or the control condition, with allocation concealment and locking of emails to minimize duplicate sign ups. |
| Incomplete outcome data (attrition bias) | Low risk | Control and intervention were compared using logistic regression according to the ITT principle with participants lost to follow‐up treated as smokers. 33% were lost to follow‐up with no significant differences between control and intervention. |
| Selective reporting (reporting bias) | Low risk | Both primary and secondary outcomes are reported. |
| Other bias | Unclear risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Smoking was not biochemically validated and was self‐report. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Unclear as to whether women were blinded regarding their allocation, providers not applicable as this was a computer‐generated intervention. |
| Blinding of outcome assessment (detection bias) | Low risk | Main outcome was self‐report of smoking status. |
| Incomplete implementation | Unclear risk | 33.5% lost to follow‐up. |
| Equal baseline characteristics in study arms | Low risk | No differences between study arms in baseline characteristics. |
| Contamination of control group | Low risk | Intervention and control were automated websites. |
| Methods | Randomised controlled study of health education and feedback to support women to stop smoking. Location and study dates unclear. Assume USA due to author affiliations. | |
| Participants | Inclusion criteria: Women enrolling for prenatal care. Exclusion criteria: Not further specified. Recruitment: 49 women randomised (I = 26, C = 23). Baseline characteristics: Not reported (abstract only). | |
| Interventions | Control: Usual prenatal care. Intervention: Education and at least 8 encounters with a program counsellor. Peak flow values and CO levels were obtained at each prenatal visit and shared with intervention group participants only. Main intervention strategy and intensity not coded as outcomes not reported. | |
| Outcomes | Smoking cessation (biochemically validated) was collected but actual figures not reported so unable to include results in this meta‐analysis. Peak flow values reported. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | States ‘women were randomised into two groups’. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Unclear risk | Data not reported. |
| Selective reporting (reporting bias) | High risk | Actual figures not reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation of smoking status using urine cotinine and CO (cut‐off levels not reported). |
| Blinding of participants and personnel (performance bias) | High risk | Participants and personnel unlikely to be blinded to educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Not reported. |
| Equal baseline characteristics in study arms | Low risk | Groups similar with maternal age, Fagerstrom scores, initial peak flow values and initial urine cotinine levels. |
| Contamination of control group | Unclear risk | Not stated who delivered intervention. |
| Methods | This 3‐armed randomised controlled trial aimed to investigate different schedules of financial incentives for smoking cessation in pregnant women and its impact on cessation. This study was conducted in Burlington VT in the USA between 2006‐2011 and women were recruited from obstetric practices and the Women, Infants, and Children (WIC) office. | |
| Participants | Inclusion criteria: Smoking in the past 7 days, gestational age ≤ 25 weeks, residing within the county in which clinic is located, plan to remain in the geographical area for ≥ 6 months following delivery, and English speaking. Exclusion criteria:incarceration, previous participation in a voucher‐based incentive trial for smoking cessation, currently residing with a trial participant, regular use of opioid, psychomotor stimulant, or antipsychotic medications. Recruitment:43.8% participation rate (C = 42 I = 44). Baseline characteristics:Partner smokes % (A = 77 B = 85 C = 82) Mean age first started smoking (A = 15.2 B = 16.3 C = 14.9) Married% (A = 21 B = 18 C = 10). Progress + coding: Low SES, women were recruited from WIC. | |
| Interventions | A: Control: In this condition, vouchers were delivered independent of smoking status. Voucher values were $15.00 per visit antepartum and $20.00 per visit postpartum, values that resulted in payment amounts comparable to average earnings in the CV condition in prior trials (Heil et al., 2008). All else was the same as in the CV and RCV conditions. B: Intervention 1: Usual contingent voucher condition (CV)—Vouchers redeemable for retail items were earned contingent on submitting breath CO specimens ≤ 6 ppm during the initial 5 days of the cessation effort. Beginning in Week 2, vouchers were delivered contingent on urine‐cotinine levels ≤ 80 ng/mL, a criterion that required a longer duration of smoking abstinence than breath CO (Higgins et al., 2007a). Voucher delivery was independent of self‐reported smoking status and based exclusively on meeting the biochemical‐verification criterion. Unauthorised failure to complete a scheduled assessment was treated as a positive test result consistent with an ITT approach (Friedman et al., 1998). Vouchers began at $6.25, and escalated by $1.25 per consecutive negative specimen to a maximum of $45.00, where they remained barring positive test results or missed abstinence monitoring visits. Positive test results or missed visits reset the voucher value back to the original low value, but 2 consecutive negative tests restored the value to the pre‐reset level. C: Intervention 2: Revised contingent voucher condition (RCV)—The same voucher schedule as outlined above was followed in this RCV condition except that potential earnings were rescheduled, moving $296.25 forward as bonuses available during Weeks 1–6 by meeting a ≤ 4 ppm breath CO criterion during Week 1, testing cotinine negative at the first urine test on the 2nd Monday of the quit attempt, and thereafter by submitting 2 cotinine‐negative specimens per week through Week 6. More specifically, bonuses earned by reaching a cut‐off of ≤ 4 ppm CO during Week 1 started at $18.75 and increased by $3.75 for each successive negative sample reaching a maximum potential bonus of $33.75 for the 5th consecutive negative specimen meeting the ≤ 4‐ppm CO cut‐off during Week 1. Women in this condition earned the same incentive as in the CV condition if they met the ≤ 6 ppm CO but not the ≤ 4 ppm cut‐off in Week 1. The goal was to provide bonuses for those who could achieve this more stringent criterion and thus decrease the likelihood of low‐level smoking that can undermine longer‐term abstinence (Higgins et al., 2006), but assure that a woman still received an incentive if she met the slightly more liberal criterion ≤ 6 ppm criterion effective in prior trials (Higgins et al., 2012). Testing cotinine‐negative on the 2nd Monday resulted in an additional bonus of $87.50 above usual CV incentive earnings on that date. 5 more bonuses of $15.50 each were available on Thursdays (2nd test day of each week) during Weeks 2–6 if a woman also had tested negative for smoking at the earlier test conducted that same week. Main Intervention Strategy: Incentives (multiple) v alternative intervention. Arms A and B are compared in this study ID, please see Higgins 2014 (AvC) for arms A and C. Intensity: Frequency (C = 6 I = 6) Duration (C = 6 I = 6). | |
| Outcomes | Biochemically verified 7‐day smoking abstinence at 24 weeks' gestation*, Continued smoking at 12 weeks postpartum (0‐5 months)* Continued smoking at 24 weeks postpartum (6‐12 months)*, Birthweight*, LBW*, preterm births*, NICU admissions*, gestational age, estimated fetal growth (fetal weight gain, abdominal circumference, femur length, head circumference, biparietal diameter, lean thigh area. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Women were randomised to the 3 different conditions, however does not explain how this was done. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | All randomised women were included in the primary analysis with the exception of fetal demise (A = 3, B = 5, C = 4). |
| Selective reporting (reporting bias) | Low risk | Both primary and secondary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking abstinence was biochemically validated, breath specimens were analysed using CO monitors and urine cotinine levels determined using onsite enzyme immunoassay testing |
| Blinding of participants and personnel (performance bias) | Unclear risk | Unclear. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Unclear |
| Equal baseline characteristics in study arms | Unclear risk | Only 2 characteristics differed significantly between treatment conditions: more of those assigned to the RCV condition worked outside the home compared to the CV but not the NCV conditions, and those assigned to the RCV condition reported higher mean ratings of stress across past week than those assigned to the CV but not the NCV conditions (Table 1). These 2 characteristics were not significantly correlated with smoking abstinence or birth outcomes. |
| Contamination of control group | Low risk | As main intervention component was incentives, no risk of contamination of control group. |
| Methods | This 3‐armed randomised controlled trial aimed to investigate different schedules of financial incentives for smoking cessation in pregnant women and its impact on cessation. This study was conducted in Burlington VT in the USA between 2006‐2011 and women were recruited from obstetric practices and the Women, Infants, and Children (WIC) office. | |
| Participants | Inclusion criteria: Smoking in the past 7 days, gestational age ≤ 25 weeks, residing within the county in which clinic is located, plan to remain in the geographical area for ≥ 6 months following delivery, and English speaking. Exclusion criteria:incarceration, previous participation in a voucher‐based incentive trial for smoking cessation, currently residing with a trial participant, regular use of opioid, psychomotor stimulant, or antipsychotic medications. Recruitment:43.8% participation rate (C = 42 I = 44). Baseline characteristics:Partner smokes % (A = 77 B = 85 C = 82) Mean age first started smoking (A = 15.2 B = 16.3 C = 14.9) Married% (A = 21 B = 18 C = 10). Progress + coding: Low SES, women were recruited from WIC. | |
| Interventions | A: Control: In this condition, vouchers were delivered independent of smoking status. Voucher values were $15.00 per visit antepartum and $20.00 per visit postpartum, values that resulted in payment amounts comparable to average earnings in the CV condition in prior trials (Heil et al., 2008). All else was the same as in the CV and RCV conditions. B: Intervention 1: Usual contingent voucher condition (CV)—Vouchers redeemable for retail items were earned contingent on submitting breath CO specimens ≤ 6 ppm during the initial 5 days of the cessation effort. Beginning in Week 2, vouchers were delivered contingent on urine‐cotinine levels ≤ 80 ng/mL, a criterion that required a longer duration of smoking abstinence than breath CO (Higgins et al., 2007a). Voucher delivery was independent of self‐reported smoking status and based exclusively on meeting the biochemical‐verification criterion. Unauthorised failure to complete a scheduled assessment was treated as a positive test result consistent with an ITT approach (Friedman et al., 1998). Vouchers began at $6.25, and escalated by $1.25 per consecutive negative specimen to a maximum of $45.00, where they remained barring positive test results or missed abstinence monitoring visits. Positive test results or missed visits reset the voucher value back to the original low value, but 2 consecutive negative tests restored the value to the pre‐reset level. C: Intervention 2: Revised contingent voucher condition (RCV)—The same voucher schedule as outlined above was followed in this RCV condition except that potential earnings were rescheduled, moving $296.25 forward as bonuses available during Weeks 1–6 by meeting a ≤ 4 ppm breath CO criterion during Week 1, testing cotinine negative at the first urine test on the 2nd Monday of the quit attempt, and thereafter by submitting 2 cotinine‐negative specimens per week through Week 6. More specifically, bonuses earned by reaching a cut‐off of ≤ 4 ppm CO during Week 1 started at $18.75 and increased by $3.75 for each successive negative sample reaching a maximum potential bonus of $33.75 for the 5th consecutive negative specimen meeting the ≤ 4‐ppm CO cut‐off during Week 1. Women in this condition earned the same incentive as in the CV condition if they met the ≤ 6 ppm CO but not the ≤ 4 ppm cut‐off in Week 1. The goal was to provide bonuses for those who could achieve this more stringent criterion and thus decrease the likelihood of low‐level smoking that can undermine longer‐term abstinence (Higgins et al., 2006), but assure that a woman still received an incentive if she met the slightly more liberal criterion ≤ 6 ppm criterion effective in prior trials (Higgins et al., 2012). Testing cotinine‐negative on the 2nd Monday resulted in an additional bonus of $87.50 above usual CV incentive earnings on that date. 5 more bonuses of $15.50 each were available on Thursdays (2nd test day of each week) during Weeks 2–6 if a woman also had tested negative for smoking at the earlier test conducted that same week. Main Intervention Strategy: Incentives (multiple) v alternative intervention. Here arms A and C are compared, please see Higgins 2014 (AvB) for arms A and B. Intensity: Frequency (A = 6, I = 6) Duration (A = 6, I = 6). | |
| Outcomes | Biochemically verified 7‐day smoking abstinence at 24 weeks' gestation* Continued smoking at 24 weeks postpartum*, Continued smoking at 12 weeks postpartum* Birthweight*, LBW*, gestational age, preterm births*, NICU admissions*, estimated fetal growth (fetal weight gain, abdominal circumference, femur length, head circumference, biparietal diameter, lean thigh area. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Women were randomised to the 3 different conditions, however does not explain how this was done. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | All randomised women were included in the primary analysis with the exception of fetal demise (A = 3, B = 5, C = 4). |
| Selective reporting (reporting bias) | Low risk | Both primary and secondary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking abstinence was biochemically validated, breath specimens were analysed using CO monitors and urine cotinine levels determined using onsite enzyme immunoassay testing |
| Blinding of participants and personnel (performance bias) | Unclear risk | Unclear. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Unclear. |
| Equal baseline characteristics in study arms | High risk | Only 2 characteristics differed significantly between treatment conditions: more of those assigned to the RCV condition worked outside the home compared to the CV but not the NCV conditions, and those assigned to the RCV condition reported higher mean ratings of stress across past week than those assigned to the CV but not the NCV conditions (Table 1). These 2 characteristics were not significantly correlated with smoking abstinence or birth outcomes. |
| Contamination of control group | Low risk | As main intervention component was incentives, no risk of contamination of control group. |
| Methods | Quasi‐randomised trial of a self‐help manual to support women to stop smoking in pregnancy. Study conducted in public health maternity clinics in Gothenburg, Sweden, with data collection from 1987 to 1988. | |
| Participants | Inclusion criteria: Pregnant women registered as daily smokers (at least 1 cigarette per day), gestational age less than 12 weeks, and speak Swedish. Exclusion criteria: Not further specified. Recruitment: 13/14 public health clinics participated. Women born days 1‐10 of each month were allocated to the control group and women born on days 11‐31 were allocated to the intervention group. Unequal group sizes were allocated as it was expected more intervention women would refuse to participate. 723 eligible continuing smokers were randomised (C = 231, I = 492). 417/492 (85%) of the intervention group agreed to participate, and the control group were not asked for consent. Baseline characteristics: Mean cigarettes/day 16.8. Mean age 28.4 years. Progress + coding: None. | |
| Interventions | Control: Given an information sheet by their doctor with basic facts about smoking and pregnancy, as included in the last pages of the self‐help manual. Intervention: Given a self‐help manual on stopping smoking, based on Windsor 1985 (AvC). The manual was revised and pilot tested. The manual contained 2 phases, a preparatory (one week) and cessation phase. The smoker was given new assignments every day to the quit day and the tasks were based on the principle of behaviour therapy. The cessation period was followed for the first 5 days with new information daily. Main intervention strategy: Health education (single intervention) compared to less intensive intervention. Intensity: Frequency (C = 1, I = 1), Duration (C = 1, I = 1). Intervention provided by existing staff (obstetrician provided self‐help manual): Effectiveness study. | |
| Outcomes | Biochemically validated smoking cessation at 30‐34 weeks' gestation (late pregnancy*), 8 weeks postpartum (0‐5 months), mean birthweight*, preterm births* (< 36 wks), LBW babies*, mean cigarettes per day at 30‐34 weeks' gestation among baseline smokers*. Mean cigarettes per day at baseline, week 12‐14, week 30‐34 among all randomised women, 8 weeks after delivery among baseline smokers and all randomised women. | |
| Notes | SDs for mean birthweight were not reported, therefore we calculated a mean SD from 13 studies with available birthweight SDs (578) to include in this review, as recommended by the cochrane handbook. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | High risk | Allocation by birth date is not random sequence. However, this study was included as interference is unlikely with birth dates. |
| Allocation concealment (selection bias) | High risk | Allocation would not be concealed as allocated by birth dates (days 1‐10 = control, days 11‐31 = intervention). |
| Incomplete outcome data (attrition bias) | Unclear risk | Loss to follow‐up from miscarriage and moving out of district (C = 10% or 23, I = 11% or 46), not included in analysis. However, all other dropouts included as continuing smokers. |
| Selective reporting (reporting bias) | Low risk | All primary outcomes appear to be reported. |
| Other bias | High risk | Unclear why there are 444 in intervention group and 209 in control group, when report states 10% of 231 were excluded and 11% of 492 were excluded. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation of smoking status using serum thiocyanate (100 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Participants and personnel unlikely to be blinded. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Manual given to all women who agreed to participate (85% of total assigned to intervention ‐ i.e. 15% refused to participate) |
| Equal baseline characteristics in study arms | Unclear risk | Only age and mean no of cigarettes reported. |
| Contamination of control group | Low risk | Unlikely control group would accidentally be given the self‐help manual. |
| Methods | Randomised controlled trial of stage of change orientated MI to support women to stop smoking in pregnancy. The study was conducted in infertility and prenatal clinics in 3 hospitals in Ontario (Canada), with data collection from January 1996 to July 1999. | |
| Participants | Inclusion criteria: Newly referred infertile and pregnant patients who reported smoking more than 3 cigarettes in past 6 months. Exclusion criteria: Women attending genetic counselling or with habitual abortion or who had previously been evaluated in consultation. Recruitment: All women attending infertility and prenatal clinics who reported smoking were invited. Unclear how many were eligible. 110 pregnant women randomised (I = 56, C = 54). Baseline characteristics: Mean cigarettes/day = 12.19 (SD 6.81); (I = 13.43 +‐7.07, C = 12 +‐ 6.69 | |
| Interventions | Control: Standard information that was already provided in the clinics about the impact of smoking on pregnancy. Intervention: Scripted stage‐based information and encouragement to quit at each prenatal visit by physicians, Stage‐specific information booklet, optional referral for more in‐depth counselling in a smoking cessation clinic. Main intervention strategy: Counselling (tailored intervention) compared with UC. Intensity not coded as outcomes unable to be included in meta‐analysis. | |
| Outcomes | Stage of change, biochemically validated cessation at 12 months post follow‐up but data for intervention and control groups were combined so outcomes were unable to be included in this review. See Table 2 for description of outcomes. Relative value of intervention components reported. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Randomised using computer‐generated, blocked schedule, administered through numbered, opaque, sealed envelopes. |
| Allocation concealment (selection bias) | Low risk | Opaque sealed envelopes. |
| Incomplete outcome data (attrition bias) | Unclear risk | No attrition reported and not stated how, if any, dropouts were assessed. |
| Selective reporting (reporting bias) | High risk | Smoking cessation outcomes not reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Biochemical validation with exhaled CO, but levels used to determine smoking status were not reported. |
| Blinding of participants and personnel (performance bias) | High risk | Providers and women not able to be blinded. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not stated whether outcome assessors blinded. |
| Incomplete implementation | Unclear risk | Process evaluation not reported. |
| Equal baseline characteristics in study arms | Low risk | No significant differences noted. |
| Contamination of control group | High risk | Same care providers offering intervention and control interventions, therefore high risk of contamination. |
| Methods | This 2‐armed randomised controlled trial of a broader nurse home‐visiting intervention to improve maternal and child health with a tobacco cessation component. This study was conducted in the home setting in a socio‐economically disadvantaged area of Sydney, New South Wales (Australia) from February 2003 to March 2005. | |
| Participants | Inclusion criteria: Mothers living in the 2168 postcode, who were able to communicate in English, were booked into their local public hospital for confinement and reported 1 or more risk factors for poor maternal or child outcomes, unclear how baseline smoking status was assessed. Exclusion criteria: Mothers who needed an interpreter and those who did not have risk factors for poor maternal and child outcomes Recruitment: Participants were recruited from public hospitals. 338 women were eligible, with 208 randomised (smokers and non‐smokers), with 73 smokers included in the analysis (C = 31 I = 42). Participation rate unclear. Baseline characteristics: No baseline characteristics of the subgroup of smokers reported. Progress + coding: None, as unable to determine characteristics of subgroup of smokers. | |
| Interventions | Control: Usual universal care, in accordance with standard practice in New South Wales. Intervention: A sustained and structured nurse home visiting AN and postnatal parenting education and support programme based on an ecological framework. Main Intervention strategy: Maternal health intervention with smoking cessation component: social support (multiple) vs UC Intensity: Frequency (C = 0 I = 6) Duration (C = 0 I = 4). Intervention conducted by researchers: efficacy study. | |
| Outcomes | Self‐reported continuous abstinence 0‐24 months (18 + months postpartum)* Household always smoke free (0‐24 months) other outcomes not reported by smoking status. See Table 2 for summary of results. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | A permuted block design was used to randomly allocate mothers to the intervention or comparison group. |
| Allocation concealment (selection bias) | Low risk | Allocation was concealed from all nurses and other research staff until after mothers consented to participate in the study and baseline data had been collected by the research assistant blinded to the allocation. |
| Incomplete outcome data (attrition bias) | Unclear risk | States that ITT analysis was used, however also states that those who had not completed any data points for the outcomes were deleted form analysis. |
| Selective reporting (reporting bias) | Unclear risk | No smoking outcomes are reported, only 2 years postpartum. |
| Other bias | Unclear risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Smoking is not biochemically validated. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Not explicitly reported, however not feasible to blind participants to a social support intervention. |
| Blinding of outcome assessment (detection bias) | Low risk | Standardised testing was undertaken by child psychologists who were blinded to group allocation. |
| Incomplete implementation | Unclear risk | Not reported |
| Equal baseline characteristics in study arms | Low risk | No significant differences noted among smokers and non‐smokers. |
| Contamination of control group | Low risk | Main component home visit. |
| Methods | Cluster‐randomised controlled trial to support women to stop smoking and prevent relapse during pregnancy and postpartum. Study conducted in public prenatal and WIC clinics in Maryland, Colorado and Missouri (USA), with data collection from 1987 to 1991. | |
| Participants | Inclusion criteria: Smoking defined as "even a puff within the last 7 days before the women knew she was pregnant", who were aggregated into 'enrolment smokers' (smoked within 7 days before study enrolment) and 'recent quitters (smoked before they thought they were pregnant). Exclusion criteria: Not further specified. Recruitment: 1741/5262, 1936/6087 and 1895/4943 pregnant women screened in Colorado, Missouri and Maryland respectively, with nearly 50% of women in each state smoking. Participation rates ranged from 66% in Maryland to 79% in Missouri. Baseline characteristics: Mean cigarettes/day at enrolment combined for smokers = 12 cigarettes/day. High proportions were young, < 12 years education, white, unmarried and poor. Mean gestation at enrolment = 15.2 ‐ 16.6 weeks. Progress + coding: Low SES. | |
| Interventions | Control: UC not otherwise specified by usual clinic staff. Main intervention strategy: Counselling (multiple intervention) compared to UC. Intensity: Frequency (C = 0, I = 2), Duration (C = 0, I = 1). UC intensity: F = 0, D = 0. Intervention provided by existing staff: Effectiveness study. | |
| Outcomes | Biochemically validated point prevalence abstinence at 8 months gestation (late pregnancy*). Smoking outcomes for 'recent quitters' (relapse prevention) were not reported. Birthweight and proportion of LBW babies are not reported by intervention group so were unable to be included in meta‐analysis. | |
| Notes | Intracluster correlation of 0.003 reported and used for adjusting outcome figures in analysis. Substantial misclassification of self‐report as non‐smoking: 28% at enrolment; 35% at 8th month; 49% of self‐reported quitters at intervention clinics; 32% of self‐reported quitters at control clinics. Process evaluation suggested less difference between I and C clinics than might have been expected. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Clinics stratified by size of clinic and also by prior LBW programme (Colorado) or % minority clients (Maryland), and randomly assigned to deliver either intervention or continue with standard care. No details of randomisation provided. |
| Allocation concealment (selection bias) | Unclear risk | Cluster‐randomised trial. |
| Incomplete outcome data (attrition bias) | High risk | In the 3 states combined, the reasons for loss to follow‐up at the 8th month were early termination of pregnancy (7.6%); enrolment after 32 weeks (6.1%); lost, moved, or unable to locate (27.7%); referred to another care provider (2.8%); and refused data collection (1.0%). The total numbers of enrolment smokers were not reported by intervention groups, and attrition rates were not reported by intervention groups, so we were unable to re‐include data for respondents lost to follow‐up. Report states loss to follow‐up was balanced in experimental and control groups. Varying enrolment and attrition rates in different centres. No ITT analysis. |
| Selective reporting (reporting bias) | Unclear risk | High rates of non‐disclosure for smoking outcomes. |
| Other bias | Unclear risk | Uneven recruitment to study arms in Maryland, which affected the overall allocation (C = 1767, I = 1467). |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation by urinary cotinine (> 85 ng/mL indicates active smoker). |
| Blinding of participants and personnel (performance bias) | Unclear risk | Unclear whether participants and providers were aware of clinic allocation. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Process evaluation reported that implementation was less than ideal. |
| Equal baseline characteristics in study arms | Low risk | Intervention and control sites were similar at enrolment, indicating that stratification and randomisation had been effective (data not shown). |
| Contamination of control group | Unclear risk | Many patients at control clinics also reported having received (non‐SCIP) materials and counselling which indicated that UC included exposure to smoking cessation messages. |
| Methods | 3‐armed cluster‐randomised trial of self‐help manuals and computer‐generated advice to support women to stop smoking in pregnancy. Study conducted in community midwife clinics in the West Midlands region of the UK, with data collection from July 1998 to March 2001. | |
| Participants | Inclusion criteria: Head midwife in every trust in region invited to participate and 16/19 agreed to participate. 204 potential midwifery practices identified, and 103 excluded by head midwife as those trusts were already involved in other regions or the practice crossed trust boundaries. Women were eligible if aged 16 years or over and a 'current smoker' at booking. Exclusion criteria: Women not fluent in English. Recruitment: 72/101 practices were randomly sampled (C = 24, I1 = 24, I2 = 23). Further practices were later added to each arm due to slow recruitment, particularly in the control arm (C = 17, I1 = 12, I2 = 0), leaving active practices (C = 32, I1 = 30, I2 = 22). Participating midwives were asked to recruit all eligible women seen in routine AN appointments. Initial target of 1440 participants was reduced to 900 due to slow recruitment. Eligible smokers approached: C = 328/965 (34%),I1 (manuals) = 327/694 (47%), I2 (computer) = 397/529 (75%). Participation rate: C = 289/328 (88%), I1 = 305/327 (93%),I2 = 324/397 (82%). Baseline characteristics: Mean cigarettes per day at baseline were similar between groups (reported in 6 smoking categories). Majority (over 60%) smoked 5‐20 cigarettes per day and over 50% had a partner who smoked. Median Fagerstrom score 3 in all arms. 63.6% of participants on < $300/week. Progress + coding: Low SES. | |
| Interventions | A: Control: Standard care. Midwives received a half‐day training on research protocol, and asked all midwives to give women the Health Education Authority booklet "Thinking about stopping". B: Intervention 1 (self‐help booklets): Midwives received 2 and a half days training on theory of transtheoretical model. Participants received a set of 6 stage‐based self‐help manuals "Pro‐Change programme for a healthy pregnancy". The midwife assessed each participant's stage of change and pointed the woman to the appropriate manual. No more than 15 mins was spent on the intervention. C: Intervention 2 (self‐help booklets + computerised advice): Midwives received the same training as for I1, and participants received the same self‐help manual and intervention as I1. Additionally, the participants used a computer programme, which consisted of questions and auto feedback of what stage they were in and what this meant, and a range of other concepts. It took about 20 mins for the woman to complete. Printed information of the feedback was sent to the participant within a week of the intervention. Main intervention strategy: Counselling (single intervention) compared with UC. Intervention 1(arm B) was compared with the control arm in this study ID. Intensity: Frequency (C = 0, I = 2); Duration (C = 0, I = 1). Intervention provided by existing staff (Midwives providing self‐help manuals): effectiveness study. | |
| Outcomes | Biochemically validated point prevalence abstinence at 28‐30 weeks' gestation (late pregnancy)* (T3) and 10 days post‐birth* (T4) (0‐5 months postpartum). Subsequent papers (Lawrence 2005b) measure and describe self‐reported smoking cessation at 18 months postpartum, movement in stage of change, partner quitting, social support mobilisation, and the stress of receiving the intervention (Lawrence 2002). | |
| Notes | Intracluster correlation of 0.003 reported in sample size calculation (see Kendrick 1995) and used for adjusting outcome data included in this meta‐analysis. Sample size calculation given, but unable to recruit sufficient numbers. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | A computerised minimisation programme was used to stratify 72 eligible practices into 3 equal groups from 101 available practices. |
| Allocation concealment (selection bias) | High risk | Further practices were added to the sample because of slow recruitment ‐ these were not randomly allocated. |
| Incomplete outcome data (attrition bias) | Low risk | Different rates of recruitment and follow‐up in different arms of the trial. 272 (C = 1 04, I1 = 86, I2 = 82) women (22.5%) withdrew from the study or were lost to follow‐up. Data on smoking status were only available for 67% of women. Where there was no urine sample available women were treated as continuing smokers. All randomised participants were included in the denominator in this analysis, with only those reported as confirmed non‐smokers at T4 included as quitters. |
| Selective reporting (reporting bias) | Unclear risk | Not apparent. |
| Other bias | High risk | Slow recruitment to standard care arm, so additional practices needed to be added. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Urinary cotinine analysis (< 1.5 ug/L). |
| Blinding of participants and personnel (performance bias) | High risk | Neither providers nor women blinded to this educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported |
| Incomplete implementation | Low risk | 77% T4 questionnaires complete in I2. |
| Equal baseline characteristics in study arms | Low risk | There was little difference at recruitment between the midwives or recruited women in the 3 trial arms. |
| Contamination of control group | Low risk | Cluster design to reduce risk of contamination. |
| Methods | 3‐armed cluster‐randomised trial of self‐help manuals and computer‐generated advice to support women to stop smoking in pregnancy. Study conducted in community midwife clinics in the West Midlands region of the UK, with data collection from July 1998 to March 2001. | |
| Participants | Inclusion criteria: Head midwife in every trust in region invited to participate and 16/19 agreed to participate. 204 potential midwifery practices identified, and 103 excluded by head midwife as those trusts were already involved in other regions or the practice crossed trust boundaries. Women were eligible if aged 16 years or over and a 'current smoker' at booking. Exclusion criteria: Women not fluent in English. Recruitment: 72/101 practices were randomly sampled (C = 24, I1 = 24, I2 = 23). Further practices were later added to each arm due to slow recruitment, particularly in the control arm (C = 17, I1 = 12, I2 = 0), leaving active practices (C = 32, I1 = 30, I2 = 22). Participating midwives were asked to recruit all eligible women seen in routine AN appointments. Initial target of 1440 participants was reduced to 900 due to slow recruitment. Eligible smokers approached: C = 328/965 (34%),I1 (manuals) = 327/694 (47%), I2 (computer) = 397/529 (75%). Participation rate: C = 289/328 (88%), I1 = 305/327 (93%),I2 = 324/397 (82%). Baseline characteristics: Mean cigarettes per day at baseline were similar between groups (reported in 6 smoking categories). Majority (over 60%) smoked 5‐20 cigarettes per day and over 50% had a partner who smoked. Median Fagerstrom score 3 in all arms. 63.6% of participants on < $300/week. Progress + coding: Low SES. | |
| Interventions | A: Control: Standard care. Midwives received a half‐day training on research protocol, and asked all midwives to give women the Health Education Authority booklet "Thinking about stopping". B: Intervention 1 (self‐help booklets): Midwives received 2 and a half days training on theory of transtheoretical model. Participants received a set of 6 stage‐based self‐help manuals "Pro‐Change programme for a healthy pregnancy". The midwife assessed each participant's stage of change and pointed the woman to the appropriate manual. No more than 15 mins was spent on the intervention. C: Intervention 2 (self‐help booklets + computerised advice): Midwives received the same training as for I1, and participants received the same self‐help manual and intervention as I1. Additionally, the participants used a computer programme, which consisted of questions and auto feedback of what stage they were in and what this meant, and a range of other concepts. It took about 20 mins for the woman to complete. Printed information of the feedback was sent to the participant within a week of the intervention. Main intervention strategy: Counselling (multiple intervention) compared with UC. Intervention 2 (arm c) was compared with the control arm in this study ID. Intensity: Frequency (C = 0, I = 3); Duration (C = 0, I = 3). Intervention provided by existing staff (Midwives providing self‐help manuals): effectiveness study. | |
| Outcomes | Biochemically validated point prevalence abstinence at 28‐30 weeks' gestation (late pregnancy)* (T3) and 10 days post‐birth* (T4) (0‐5 months postpartum). Subsequent papers (Lawrence 2005b) measure and describe self‐reported smoking cessation at 18 months postpartum, movement in stage of change, partner quitting, social support mobilisation, and the stress of receiving the intervention. | |
| Notes | Intracluster correlation of 0.003 reported in sample size calculation (see Kendrick 1995) and used for adjusting outcome data included in this meta‐analysis. Sample size calculation given, but unable to recruit sufficient numbers. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | A computerised minimisation programme was used to stratify 72 eligible practices into 3 equal groups from 101 available practices. |
| Allocation concealment (selection bias) | High risk | Further practices were added to the sample because of slow recruitment ‐ these were not randomly allocated. |
| Incomplete outcome data (attrition bias) | Low risk | Different rates of recruitment and follow‐up in different arms of the trial. 272 (C = 1 04, I1 = 86, I2 = 82) women (22.5%) withdrew from the study or were lost to follow‐up. Data on smoking status were only available for 67% of women. Where there was no urine sample available women were treated as continuing smokers. All randomised participants were included in the denominator in this analysis, with only those reported as confirmed non‐smokers at T4 included as quitters. |
| Selective reporting (reporting bias) | Unclear risk | Not apparent. |
| Other bias | High risk | Slow recruitment to standard care arm, so additional practices needed to be added. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Urinary cotinine analysis (< 1.5 ug/L). |
| Blinding of participants and personnel (performance bias) | High risk | Neither providers nor women blinded to this educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported |
| Incomplete implementation | Low risk | 77% T4 questionnaires complete in I2. |
| Equal baseline characteristics in study arms | Low risk | There was little difference at recruitment between the midwives or recruited women in the 3 trial arms. |
| Contamination of control group | Low risk | Cluster design to reduce risk of contamination. |
| Methods | This 2‐armed randomised controlled trial of a theory‐guided cognitive‐behavioural counselling (CBC) intervention for smoking cessation during pregnancy. Participants were recruited at the Women, Infants and Children Clinics (WIC) in Center in Philadelphia USA with recruitment occurring between January 2003 to May 2007. | |
| Participants | Inclusion criteria: Women were eligible for study participation if they: 1) were pregnant (between 1–25 weeks post‐gestation); 2) had smoked at least 1 puff of a cigarette in the 30 days prior to the recruitment; 3) were 18 years or older; and 4) were reachable by a telephone at the point of initial contact. Exclusion criteria: Participants who had miscarriages, stillbirth, and neonatal death during the study period were dropped from the study. Recruitment: Participants were recruited from WIC clinics at their prenatal clinic visit, where written consent was obtained. 513 women were eligible, with 277 randomised 54% participation (C = 137 I = 140). Baseline characteristics: Mean cigarettes/day C = 7.90 (7.62) I = 7.37 (7.17) Fagerstrom score: C = 2.01 (1.11), I = 2.04 (1.14). Participants were predominantly non‐White (African American = 56% and Hispanic = 12%; non‐Hispanic White = 33.83%), single (89%), low‐income (50% < $15,000), with a mean age of 27 years, education level of high school or less (> 50%), and with an average of 2 children in the household. Approximately 40% 12 years education or above. > 85% single. 63% Black, 12%‐13% Hispanic, 23%‐24% white. 'Low‐income, uninsured women'. | |
| Interventions | Control: 5A's model of smoking cessation counselling was provided, though it is unclear if this was provided by routine providers or study staff. Intervention: Building on established cognitive‐affective processing protocols and guided by the C‐SHIP model, the intervention sessions were designed to identify and address participants' cognitive‐affective barriers to smoking cessation in the context of pregnancy and postpartum adaptation and provided by masters level health educators. Participants in the CBC intervention met with a health educator: for 45 mins (session 1) during their second trimester visit (13–25 weeks' gestation); for 15 mins (session 2) during their third trimester visit (26–38 weeks' gestation); and for 45 mins (session 3) during the first postpartum visit (2–6 weeks postpartum). Session 4 was a booster session delivered by telephone at 8–10 weeks postpartum for 15 min. Main Intervention strategy: Counselling (single) vs less intensive intervention. Intensity: Frequency (C = 4, I = 4) Duration (C = 2, I = 3). | |
| Outcomes | Biochemically validated smoking abstinence at late pregnancy* and 1 and 5* months post partum. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Following the baseline assessment, participants were allocated to either: (1) the C‐SHIP based CBC intervention; or (2) the BP control condition, using computer‐generated random number sequences. |
| Allocation concealment (selection bias) | Low risk | Allocation was concealed from all nurses and other research staff until after mothers consented to participate in the study and baseline data had been collected by the RA blinded to the allocation. |
| Incomplete outcome data (attrition bias) | Low risk | Both ITT and responder‐only approaches were conducted for each follow‐up time point. For the ITT approach, participants who did not complete follow‐up assessments were coded as smokers. |
| Selective reporting (reporting bias) | Low risk | All primary outcomes seem to be reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Cessation rates were assessed through self‐reported 7‐day point prevalence abstinence which was biochemically verified through saliva cotinine level < 10 mg. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Not clear. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Details regarding who undertook the outcome assessment, not given. |
| Incomplete implementation | Unclear risk | Of the total 4 counselling sessions, 128 (46 %) completed all 4 sessions, 58 (21 %) completed 3 sessions only, and 28 (10 %) completed 2 sessions only. 63 (23%) participants never returned for the following sessions after the first session. |
| Equal baseline characteristics in study arms | Low risk | Baseline characteristics appear equal. |
| Contamination of control group | Low risk | Care providers did not provide the intervention. |
| Methods | A randomised controlled trial (RADIUS) of routine US screening to improve perinatal outcomes, including smoking in pregnancy. The study was conducted in Missouri, USA, with data collection from November 1987 to May 1991. | |
| Participants | Inclusion criteria: Last menstrual period known within 1 week, gestational age < 18 weeks, no plans to change providers. All women enrolled in the RADIUS study who reported any smoking in the year before enrolment in the study were evaluated in the subgroup analysis. Exclusion criteria: Medical or obstetric complications, planning an US for other reasons, twin pregnancy, not intending to continue pregnancy. Recruitment: 53,367 pregnant women were screened for entry into RADIUS study; 32,317 ineligible or excluded; leaving 21,050. 3163 refused (85% participation), 2357 had miscarriage or change of provider; leaving 15,530 randomised (C = 7718, I = 7812), 23.8% (3,571) of whom were smokers in year before enrolment, and 1901 who were still smoking at enrolment. 3,571 smokers included in this analysis (C = 1803, I = 1768). Baseline characteristics: 95% aged 20‐35, 95% white, Education: high school or less (C = 30%, I = 29%), some college (C = 29%, I = 30%), college graduation (C = 42%, I = 41%). Progress + coding: None. | |
| Interventions | Control: US only if ordered by their physician for medical reasons. Intervention: US at 18‐20 and 31‐33 weeks, no details about feedback to the mother or others. No specific smoking intervention provided. Main intervention strategy: Feedback (single intervention) as part of a broader intervention to improve maternal health compared to UC. Intensity: Frequency (C = 0, I = 3), Duration (C = 0, I = 2). UC intensity: F = 0, D = 0. Intervention provided by study staff: efficacy study. | |
| Outcomes | Mean number of cigarettes per day*. Self‐reported smoking cessation recorded on birth certificate, but unable to determine how many smokers in each group so smoking outcomes not included in this review. Mean birthweight, preterm births (< 36 weeks), very preterm birth (< 33 weeks), and adverse perinatal outcomes, but were not included in this review as other aspects of the intervention may have impacted on perinatal outcomes. | |
| Notes | SDs for mean cigarettes per day were not reported, therefore we calculated a mean SD from 14 studies with available mean cigarette SDs (6.5) to include in this review, as recommended by the cochrane handbook. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Stratified computer randomisation. |
| Allocation concealment (selection bias) | Unclear risk | Information not provided. |
| Incomplete outcome data (attrition bias) | Low risk | Small loss to follow‐up (approximately 2%). Miscarriage: C = 63, I = 64, records lost or moved: C = 121, I = 131, leaving C = 7534, I = 7617; Available case analysis but smoking cessation was not a primary outcome. |
| Selective reporting (reporting bias) | Low risk | None apparent. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | No biochemical validation. |
| Blinding of participants and personnel (performance bias) | Low risk | Smoking status not revealed to sonographer. Intervention not explicitly about smoking cessation. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | The mean number of sonograms obtained was 2.2 per woman in the US‐screening group. |
| Equal baseline characteristics in study arms | Low risk | Baseline characteristics appear equal. |
| Contamination of control group | Low risk | The mean number of sonograms obtained was 0.6 per woman in the control group and 55 percent had no sonograms. Only 2% of control group had 2 USs |
| Methods | A randomised controlled trial of counselling intervention to support women to stop smoking in pregnancy. The study was conducted in an AN clinic in Newcastle Hospital (UK), from March to May 1982. | |
| Participants | Inclusion criteria: All pregnant women currently smoking >= 1 cigarette a day at the time of the first AN clinic under care of 4 consultant obstetricians. Exclusion criteria: Women 28 weeks' gestation or more. Recruitment: 156 smokers identified in clinics and 5 were excluded as over 28 weeks' gestation. 151 randomised (C = 74, I = 77). Baseline characteristics: Mean cigarettes per day before pregnancy: C = 18.3, I = 18.1. Mean cigarettes per day at booking: C = 14.4, I = 15.1. Mean age: C = 25 years, I = 22.7 years. Partner unemployment: C = 53%, I = 57%. Progress + coding: Low SES as study in 'deprived area' and high partner unemployment. | |
| Interventions | Control: Usual AN care with possible exposure to a concurrent television series (6 x 10‐min programme on stopping smoking in pregnancy). Main intervention strategy: Health education (multiple intervention) compared to UC. Intensity: Frequency: (C = 0, I = 4), Duration (C = 0, I = 2) Estimate. Intervention provided by existing staff (resident): Effectiveness study. | |
| Outcomes | Self‐reported smoking cessation 9‐16 weeks after booking visit (late pregnancy*). Mean cigarettes per day* (the SD used in the analysis in this review was calculated from a P value of 0.05 given in the paper). | |
| Notes | Short interval between intervention and assessment. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as balanced "simple random allocation" in blocks. |
| Allocation concealment (selection bias) | Unclear risk | Information not provided. |
| Incomplete outcome data (attrition bias) | Unclear risk | Small loss to follow‐up, some missing data but balanced across groups. Attrition 6/151 (4%, C = 3, I = 3): not pregnant (C = 1), 1 guilt over previous stillbirth (I = 1), and miscarriages or medical complications (C = 2, I = 2). 145 included in analysis (C = 73, I = 72). |
| Selective reporting (reporting bias) | Low risk | None apparent. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | No biochemical validation of self‐reported smoking cessation. |
| Blinding of participants and personnel (performance bias) | High risk | Neither women nor providers blinded to this educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | A home visit at 4 weeks was made to the remaining 76 test patients. 31 (41%) were found at home; 29 were given further anti‐smoking advice; 45 (59%) were out and a letter of encouragement was left. |
| Equal baseline characteristics in study arms | Unclear risk | Mean age of test mothers 22.7, controls 25. Report notes other variables were equal, but figures are not reported. |
| Contamination of control group | Low risk | Main component home visit. |
| Methods | Cluster‐randomised controlled trial of 'Time for a Change' behavioural intervention to support low‐income African American and Hispanic women to stop smoking and prevent relapse in pregnancy and prevent relapse postpartum. Study conducted in 4 Women, Infant, and Children (WIC) clinics in south and central Los Angeles (USA) from October 1990 to December 1992. | |
| Participants | Inclusion criteria: 4 clinic sites identified from similar neighbourhoods and pair‐matched based on ethnic mix. Pregnant women at least 18 years of age who had smoked in the previous year. Exclusion criteria: Not further specified. Recruitment: Clinics randomly assigned. All pregnant women were asked about smoking and participants in intervention sites were asked for informed consent. 8019 women screened (419 current smokers and 692 ex‐smokers). 768/1102 (69%) current (410) or ex‐smokers (692) entered the study. 18% refused (198), 12% (132) ineligible due to young age, early delivery or referral to a different clinic. Baseline characteristics: Smoking: Current 40.5% (I = 51%, C = 36.5%); ex‐smoker 59.5% (I = 49%, C = 63.5%). Mean age 26.8 (I = 27.3, C = 26.6). African American 53%, Hispanic 42.6%. Progress + coding: Low SES in this review as WIC clinic recipients, and ethnic minority population. | |
| Interventions | Control: UC, including printed information about the risks of smoking during pregnancy and a group quit‐smoking message as part of the initial WIC visit. Intervention: (i) Assessment of smoking motivation and intention to quit. (ii) Bilingual health educators (Spanish and English) with bachelors degrees provided 15 mins individual counselling that included risk information and quit messages or reinforcement. Participants were asked to select a quit date and nominate a significant other as a 'quit buddy'. (iii) Self‐help guide 'Time for a change' with an explanation of how to use it and behavioural counselling. (iv) Explanation of how to win prizes ($100) by completing activity sheets (v) booster postcard 1 month after study entry. Main intervention strategy: Counselling (multiple intervention) compared with UC. Intensity: Frequency: (C = 0, I = 4), Duration (C = 0, I = 2). UC intensity: F = 1, D = 1. Intervention provided by dedicated study staff: efficacy study. | |
| Outcomes | Self‐reported smoking cessation and relapse prevention at 9 months gestation (late pregnancy*), and 6 weeks postpartum (0‐5 months postpartum*). Differential quit rates reported by African‐American and Hispanic ethnic status. Participants views of intervention. | |
| Notes | Adjustment for clustering not reported. Standard adjustments as described in methods in this review. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | 4 participating clinics were identified from similar neighbourhoods and pair‐matched based on ethnic mix. 2 clinics were 'randomly assigned' as control sites, and 2 clinics were assigned as intervention sites. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | High risk | 28% attrition (213/768), C = 28%, I = 25% (not stated how many from each arm, so not able to be re‐included in this review). Dropouts due to inability to contact, miscarriage or discontinuance with the WIC program. 555 included in analysis (C = 400, I = 155). |
| Selective reporting (reporting bias) | Low risk | Primary outcomes appear to be reported. |
| Other bias | High risk | Unequal recruitment to each study arm. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Self‐reported abstinence only. Only able to obtain biochemical validation with salivary cotinine (cut‐off 20 ng/mL) on 111/254 women who reported they were not smoking. High misclassification. Self‐reported rates used in this review. |
| Blinding of participants and personnel (performance bias) | High risk | Providers and women not able to be blinded due to educational nature of intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Only 12/155 women returned and completed 12 worksheets. |
| Equal baseline characteristics in study arms | High risk | Intervention group had a significantly higher proportion of smokers at baseline (51% vs 36%) and a significantly lower proportion of participants in the third trimester for the initial WIC visit (27% vs 36%). |
| Contamination of control group | Low risk | Cluster trial at service level with minimal contact with control organisations. |
| Methods | Randomised controlled trial of interventions (individual and group), based on the 'MRFIT' trial, to support women to stop smoking during pregnancy. Study conducted in 1 of 2 hospitals in the Kaiser Permanente HMO of Oregon (USA), with women recruited between July 1979 and September 1980. | |
| Participants | Inclusion criteria: Pregnant women who answered 'yes' to a questionnaire about whether they now smoked. Exclusion criteria: Not further specified. Recruitment: 3856 pregnant women screened in first AN visit: 963 self‐reported current smokers (25%) were randomised (C = 486, I = 477). All women in intervention group were invited to participate in study but high refusal rates (37%). After some changes to recruitment strategy refusal rate dropped to 30.6%. Baseline characteristics: Partner smoking: 74.1%. Mean age 23.3 years. 66.2% married. 21% smokers in receipt of public assistance but only 7% of non‐smokers. Progress + coding: None. | |
| Interventions | Control: UC: normal medical care for the duration of their pregnancy. Intervention: (i) letter of invitation, reminder letter; Main intervention strategy: Counselling (tailored intervention) compared with UC. Intensity: Frequency (C = 0, I = 6), Duration (C = 0, I = 6). Intervention provided by dedicated project staff: efficacy study. | |
| Outcomes | Self‐reported smoking cessation in late pregnancy*. Biochemically validated with cord blood thiocyanate in a random subsample (C = 24, I = 29). | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | No details of randomisation. |
| Allocation concealment (selection bias) | Unclear risk | Described as "randomly assigned". |
| Incomplete outcome data (attrition bias) | Low risk | Attrition rates high at all stages of this study. Approximately 45% lost to follow‐up. I = 271/477 (56.8%) completed last questionnaire, with 'similar numbers in control group' (C = 276/486). However. all dropouts included as continuing smokers in this review. |
| Selective reporting (reporting bias) | Unclear risk | Birth outcomes reported by smoking status, not intervention group. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Biochemical validation with urine thiocyanate at delivery on a small subsample (C = 24, I = 29). |
| Blinding of participants and personnel (performance bias) | High risk | Participants and providers not blinded to allocation. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Very poor response to group sessions so intervention changed over the course of the trial to individual counselling, which also had very low participation overall: 18% active; 25.2% dropped out; 38% did not participate; 18% could not be contacted. |
| Equal baseline characteristics in study arms | Unclear risk | Differences between intervention and control group not reported. |
| Contamination of control group | Low risk | UC providers not delivering intervention. |
| Methods | This 2‐armed randomised controlled trial, tested 30 mins of individualised cognitive‐behavioural counselling delivered by a trained healthcare professional, with participants recruited from 2 Hospitals in Athens Greece, between November 2009 and June 2012. | |
| Participants | Inclusion criteria: > 18 years old, currently pregnant and currently cigarette smokers of > 5 cigarettes over the past 7 days Exclusion criteria: > 24 weeks’ gestation at the time of entry, limited or no telephone access, not planning to live at the same address for 1 year, unable to read and/or speak Greek fluently, current alcohol or substance abusers (defined as strong cravings for alcohol, inability to limit drinking, continued use of alcohol despite the repeated problems) and current depression (according to the Greek validated version of the Goldberg’s General Health Questionnaire (GHQ) Recruitment: No information was given regarding how women were approached, however (n = 84) were randomised. Unclear how many in each study arm. Baseline characteristics: No baseline characteristics reported. Progress + coding: None. | |
| Interventions | Control: The control group consisted of a face‐to‐face low intensity intervention which lasts 5 mins and included brief advice and the provision of a leaflet on smoking and pregnancy Intervention: The intervention consisted of 30 mins of individualized cognitive‐behavioural counselling delivered by a trained healthcare professional and a self‐help manual especially tailored for smoking cessation during pregnancy. Main Intervention strategy: Counselling (single) vs less intensive intervention Intensity: Frequency (C = 1 I = 2) Duration (C = 1 I = 2). | |
| Outcomes | Mean urinary cotinine and urinary nicotine reported in abstract, but unable to be included as numbers in study arms unknown. Biochemically validated smoking status at 32nd week of gestation. Infant's birthweight, prematurity of birth, complications during pregnancy, smoking relapse among quitters at 6 months post partum were collected but results not yet reported so not included in this review. | |
| Notes | No results paper published yet, just protocol and abstract. No response from 2 emails sent to authors. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | The participants’ assignment to each group was computer‐generated |
| Allocation concealment (selection bias) | Low risk | After the informed consent form has been signed a study entry number was assigned to each participant. This number will be on the outside of an envelope, which will allocate accordingly the participant to either the experimental or the control group. |
| Incomplete outcome data (attrition bias) | Unclear risk | No information given. |
| Selective reporting (reporting bias) | Unclear risk | Outcomes not yet reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Smoking status was biochemically validated with urine cotinine. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Stated that this is a single‐blind trial and that participants will not be aware of their allocation to intervention or control butt that researchers will be aware. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | No data reported. |
| Equal baseline characteristics in study arms | Unclear risk | No information on baseline characteristics given. |
| Contamination of control group | Low risk | Care providers did not provide the intervention. |
| Methods | A randomised controlled trial of brief counselling to support women who had recently quit smoking to prevent relapse during pregnancy and postpartum. The study was conducted alongside a concurrent trial (Windsor 1993) to support women to stop smoking during pregnancy, relapse prevention among women who had stopped smoking since the beginning of pregnancy, in 4 public maternity clinics in Birmingham, Alabama (USA) from 1987 to1989. | |
| Participants | Inclusion criteria: Pregnant women reporting as having quit within 3 months of first prenatal visit. Exclusion criteria: Not further specified. Recruitment: 106/115 women who were invited agreed to participate (92%) and were randomised (C = 54, I = 52). Baseline characteristics: All recent quitters within 3 months of first visit. No other baseline characteristics reported, though report states there was no significant differences in age, race, gestation, or smoking history between intervention and control, or those lost to follow‐up. Progress + coding: None. | |
| Interventions | Control: Usual prenatal care, including nurses' advice to all women not to smoke. ii) "stay quit buddy" encouragement, non‐smoking gifts and pamphlets, iii) clinic reinforcement by prenatal staff through reminder form in the notes and to confirm abstinence, praise, encourage continuing cessation. Main intervention strategy: Counselling (multiple intervention) compared to UC. Intensity: Frequency (C = 0, I = 5), Duration (C = 0, I = 2). Intervention provided by dedicated project staff: Efficacy study. | |
| Outcomes | Biochemically validated relapse in late pregnancy*. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as "randomly assigned". |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | Unclear risk | 3 had a miscarriage, 4 moved and 2 had babies for adoption, leaving C = 2/54, I = 7/52 included in analysis. Smoking status reported on 80% (C = 38, I = 40), but ITT analysis for main outcome, so those subsequently lost to follow‐up treated as continuing smokers. |
| Selective reporting (reporting bias) | Unclear risk | Unclear what data were collected. Only smoking outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation of non‐smoking or reporting smoking less than or equal to 7 cigarettes since quitting with salivary thiocyanate analysis (cut‐off levels not stated). |
| Blinding of participants and personnel (performance bias) | High risk | Notes flagged. Providers and women not blinded to allocation. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | Process evaluation showed good implementation. |
| Equal baseline characteristics in study arms | Low risk | Figures not reported but author states there was no difference. |
| Contamination of control group | High risk | Issues of possible 'contamination' in clinics with individual randomisation discussed. |
| Methods | Cluster‐randomised trial to evaluate dissemination of a behaviourally‐based program to support women to stop smoking in pregnancy. Study conducted in Queensland (Australia). Data collection dates not stated. | |
| Participants | Inclusion criteria: Public hospitals which provided AN and delivery care for 10 or more patients a year, had less than 50% Aboriginal and Torres Strait Islander population, and did not currently provide any AN smoking cessation care. Exclusion criteria: Not further specified. Recruitment: Hospitals were matched on number of births, location of population centre (rural/metropolitan), and whether they had a specific AN clinic. 80 (92% public hospitals) hospitals eligible. 10 omitted as they stopped providing AN care. 70 hospitals (35 pairs) included. Baseline characteristics: Characteristics of individuals not reported. No outcomes included in study so not coded. | |
| Interventions | Control: Received ‘awareness’ phase of intervention based in Rogers’ Diffusion of Innovation theory. Flyers were distributed to all hospitals. Intervention: Control +‘Persuasion’ phase, which included an educational workshop and presentation. ‘Implementation phase’ where each hospital conducted the recommended program. Main intervention strategy: Intensive dissemination vs less intensive intervention. No outcomes to include in analysis. Intensity: NA | |
| Outcomes | Self‐reported implementation of program at each hospital. Success was defined as the routine offer of an evidence‐based smoking cessation program to at least 80% of the pregnant clients who smoke. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Report states hospitals were randomised into intervention and control groups, within matched pairs. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | High risk | Complete follow‐up could not be obtained primarily due to the inability to contact either the medical superintendent or the director of nursing after a minimum of 3 attempts. High attrition (37% hospitals), though those not responding were included in analysis as ‘not implemented’. |
| Selective reporting (reporting bias) | Unclear risk | Smoking cessation rates not reported, but not included as an aim of this dissemination study. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Smoking status not assessed in this dissemination study. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Unclear whether control hospitals were blinded. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not stated. |
| Incomplete implementation | High risk | 37% reported as 'not implemented'. |
| Equal baseline characteristics in study arms | Low risk | Matching of the hospitals was successful as there were no differences in number of births, rurality, and whether they had a specialised AN service at baseline. |
| Contamination of control group | Low risk | Cluster design likely to minimise risk of contamination. |
| Methods | Randomised controlled trial of peer counselling to support women to stop smoking in pregnancy. Study conducted in a large urban clinic in Hartford Hospital (USA), with recruitment from January 1998 to February 2000. | |
| Participants | Inclusion criteria: Pregnant women who smoke at least 1 cigarette per day in week before learning of pregnancy, less than 20 weeks' gestation, literate in English or Spanish, 18 years of age or older, and intending to carry to term. Exclusion criteria: Women using smokeless tobacco or nicotine replacement products, or who reported current substance abuse or dependence. Recruitment: All pregnant women screened at first prenatal visit and invited if met criteria. Informed consent obtained. Participation rate not reported, but states high smoking prevalence in pregnancy (29%) and hospital had over 4000 deliveries per year, and only 142 women recruited to study (C = 75, I = 67). Baseline characteristics: Mean cigarettes/day at baseline significantly higher in intervention group: C = 11.2 (SD 8.4); I = 13.3 (SD 13.3). Baseline CO C = 7.25 (SD 8.4), I = 5.12 (SD 5.01). Short term Fagerstrom score: C = 3.8 (2.87), I = 4.2 (2.44). Mean age C = 26, I = 26. Approximately 40% 12 years education or above. > 85% single. 63% Black, 12%‐13% Hispanic, 23%‐24% white. 'Low‐income, uninsured women'. | |
| Interventions | Control: UC, which included the program of "Ask, Advise, Arrange and Assist", based on cognitive behaviour, described by Windsor 2000a, and provision of self‐help materials, and smoking cessation counselling as per protocol as each visit. Intervention: As for the control group + peer counselling from lay community health outreach workers (telephone or home visits). Peer counsellors received 2 x 3 hours of training. Main intervention strategy: Social support (single intervention) compared to less intensive intervention. Intensity: Frequency (C = 5, I = 6), Duration (C = 2, I = 5). Intervention provided by dedicated project staff: Efficacy study. | |
| Outcomes | Biochemically validated smoking abstinence*, and reduction (cigarettes/day) at 36 weeks' gestation (late pregnancy). Mean exhaled CO. Mean birthweight* and proportion of babies* born LBW were provided by the study authors (unpublished data). | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer‐generated list. |
| Allocation concealment (selection bias) | Unclear risk | Information not provided. |
| Incomplete outcome data (attrition bias) | Low risk | High attrition rates (C = 27/75 or 36%, I = 29/67 or 43%). ITT analyses for whole sample and for those remaining at follow‐up. |
| Selective reporting (reporting bias) | Unclear risk | Birth outcomes only reported by smoking status not intervention group. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Urinary cotinine levels at baseline and at 36 weeks' gestation (200 ng/mL cut‐off). Exhaled CO at each prenatal visit (< 8 ppm). |
| Blinding of participants and personnel (performance bias) | Unclear risk | States that caregivers were masked but women may have discussed but educational/counselling support intervention that women may have discussed with caregivers. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Process evaluation suggests reasonable implementation (median 6 contacts for those who remained in study), but high attrition limits exposure to intervention. |
| Equal baseline characteristics in study arms | High risk | The peer counselling group had a greater proportion of heavier smokers at baseline. |
| Contamination of control group | High risk | Discussion notes that quit rate in control group higher than expected and that 'UC' in this trial may be more comprehensive. Which is likely as prompts etc were provided as part of trial participation to remind providers to offer support as per guidelines. Providers were also given training about the guidelines from trial staff. |
| Methods | Cluster‐randomised controlled dissemination trial of “It’s Time” program, in 33 prenatal, family planning and paediatric clinics. Study was conducted in Chicago (USA) between November 1994 and July 1996. | |
| Participants | Inclusion criteria: 33 prenatal, family‐planning and well‐child clusters at 12 public health clinics were included. Services were matched into pairs on type of public health clinic (health department, neighbourhood health centre, university clinic), location (urban/rural), and racial mix. 10 months baseline measures were taken. The intervention was randomly assigned to 6 intervention and 6 control public health clinics. Exclusion criteria: Not further specified. Recruitment: 1495 smokers identified (21% of women screened). 77% (1112) women in intervention group and 85% (1045) women in the control group agreed to participate. 63% (516) women in intervention group and 61% (548) women in control group completed the follow‐up assessments (T2). Baseline characteristics: Mean cigarettes per day: C = 10.96, I = 12.01, Black C = 68.3%, I = 81.2%, > high school ed C = 39.2%, I = 38.9%. Not coded as no outcomes included in review. | |
| Interventions | Control: Not stated. Intervention: (i) Provider focused: Charts flagged with ‘smoker’ sticker, charts prepared with booklets and agreement form, documentation; (ii) Patient focused: motivational video played in waiting room, posters, brief provider advice, booklet, agreement form, letters reminding women of advice, 15‐min motivational interview. Main intervention strategy: Counselling (multiple intervention) vs UC. Intensity not coded as no outcomes able to be included in this review. | |
| Outcomes | Dissemination and smoking cessation outcomes reported, but not able to include in this review as we were unable to separate pregnant women from women attending family planning and paediatric clinics. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Just states ‘randomly allocated’. |
| Allocation concealment (selection bias) | Unclear risk | Not stated. |
| Incomplete outcome data (attrition bias) | High risk | 37%‐39% attrition (due mostly to lack of working telephones) and not clear how accounted for in analysis. Conducted analysis which suggests those lost to attrition did not differ significantly in race, cigarettes, stage of readiness, motivation, or confidence. |
| Selective reporting (reporting bias) | Unclear risk | Actual outcomes for each service not reported so difficult to assess. |
| Other bias | Low risk | No other bias detected |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Self‐reported smoking status, not biochemically validated. |
| Blinding of participants and personnel (performance bias) | High risk | Women and provider not able to be blinded. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Not reported, despite being a dissemination trial. |
| Equal baseline characteristics in study arms | Unclear risk | Smokers in intervention clinics slightly older and more likely to be African‐American. |
| Contamination of control group | Low risk | Low risk of contamination as cluster trial. |
| Methods | This single‐blind 2‐armed randomised controlled trial of the (Healthy Pregnancy: Step by Step) is a broad maternal and child health program which aims to address smoking cessation, stress management, and fruit and vegetable consumption in pregnant women. The study was conducted in Connecticut, Rhode Island and New York in the USA from December 2011 to September 2012. | |
| Participants | Inclusion criteria: > 18 years, English or Spanish speaking, and less than 19 weeks' gestation. Exclusion criteria: Not stated. Recruitment: Prenatal health staff at each participating location invited all pregnant women who met the eligibility requirements to participate. 392 women were approached, with 117 smokers randomised (C = 60 I = 57). Baseline characteristics: Characteristics of smokers at baseline not reported. Progress + coding: None. | |
| Interventions | Control: The UC arm received a 'March of Dimes' brochure on the target behaviours at the conclusion of their first assessment. Intervention: To test an iPad‐delivered multiple behaviour tailored intervention for pregnant women that addresses smoking cessation, stress management and fruit and vegetable consumption. Main Intervention strategy: Maternal Health intervention with smoking cessation component: Health education (single) vs UC. Intensity: Frequency (C = 0 I = 3) Duration (C = 0 I = 3). | |
| Outcomes | Smoking outcomes not reported as authors state numbers were too small. Fruit and vegetable consumption and stress management reported. See Table 2 for summary of reported results. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | A randomised 2 x 2 factorial repeated measures design was employed with randomisation on the individual level stratified on behaviour risk. |
| Allocation concealment (selection bias) | Unclear risk | States that computer allocation was used so assume concealed from researchers. |
| Incomplete outcome data (attrition bias) | Unclear risk | Smoking outcomes not reported as numbers were too small. |
| Selective reporting (reporting bias) | Unclear risk | Smoking outcomes not reported as numbers were too small. |
| Other bias | Unclear risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | No evidence of validation is reported and no smoking outcomes reported. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Not reported. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Unclear as smoking was not assessed. |
| Incomplete implementation | Low risk | Process evaluation not undertaken. |
| Equal baseline characteristics in study arms | Unclear risk | Baseline characteristics appear to be equal. |
| Contamination of control group | Low risk | Intervention was self‐administered via an iPad application, so no likelihood of contamination. |
| Methods | 3‐armed randomised controlled trial comparing 2 smoking cessation interventions to support women to stop smoking in pregnancy. Study conducted in WIC clinics in Grand Rapids, Michigan (USA), from 1985 to 1986. | |
| Participants | Inclusion criteria: Pregnant women currently smoking (>= 1 cigarette/day). Exclusion criteria: Not further specified. Recruitment: 271/641 attending the clinics (42%) identified as smokers. 219/271 (81%) agreed to participate and were randomised (C = 77, I1 = 70,I2 = 72). Baseline characteristics: Mean cigarettes/day prior to pregnancy I = 19.9, C = 20.3. 75% white. 76.5% on medicaid. Progress + coding: Low SES as WIC recipients. | |
| Interventions | A: Control: UC which included printed information about the risks of smoking in pregnancy. Main intervention strategy: Health education (single intervention) compared to UC. Intervention 1 (arm B) compared with control in this study I.D. Intensity: Frequency (C = 0, I = 2), Duration (C = 0, I = 1). Unclear whether intervention provided by existing staff or dedicated project workers. | |
| Outcomes | Self‐reported smoking cessation at 9 months gestation (late pregnancy*) and approximately 4.7 weeks after birth (0‐5 months postpartum*). | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as "randomly assigned". |
| Allocation concealment (selection bias) | Unclear risk | Not stated. |
| Incomplete outcome data (attrition bias) | Low risk | 15% attrition (33/219) at follow‐up. All those lost to follow‐up were treated as continuing smokers. |
| Selective reporting (reporting bias) | Low risk | Not apparent. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Biochemically validated with salivary thiocyanate in approximately a third of participants (n = 66), but no adjustment for misclassification. |
| Blinding of participants and personnel (performance bias) | High risk | Caregivers not blinded to this educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not stated. |
| Incomplete implementation | Unclear risk | No process evaluation. |
| Equal baseline characteristics in study arms | Unclear risk | Differences between study participants and refusals on variables available from the WIC record were relatively minor for important variables as were study group differences. |
| Contamination of control group | Low risk | Health educator, not UC provider, offering intervention. |
| Methods | 3‐armed randomised controlled trial comparing 2 smoking cessation interventions to support women to stop smoking in pregnancy. Study conducted in WIC clinics in Grand Rapids, Michigan (USA), from 1985 to 1986. | |
| Participants | Inclusion criteria: Pregnant women currently smoking (>= 1 cigarette/day). Exclusion criteria: Not further specified. Recruitment: 271/641 attending the clinics (42%) identified as smokers. 219/271 (81%) agreed to participate and were randomised (C = 77, I1 = 70,I2 = 72). Baseline characteristics: Mean cigarettes/day prior to pregnancy I = 19.9, C = 20.3. 75% white. 76.5% on medicaid. Progress + coding: Low SES as WIC recipients. | |
| Interventions | A: Control: UC which included printed information about the risks of smoking in pregnancy. Main intervention strategy: Counselling (multiple intervention) compared to UC. Intervention 2 compared (arm C) with control in this review. Intensity: Frequency (C = 0, I = 2), Duration (C = 0, I = 2). Unclear whether intervention provided by existing staff or dedicated project workers. | |
| Outcomes | Self‐reported smoking cessation at 9 months gestation (late pregnancy*) and approximately 4.7 weeks after birth (0‐5 months postpartum*). | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as "randomly assigned". |
| Allocation concealment (selection bias) | Unclear risk | Not stated. |
| Incomplete outcome data (attrition bias) | Low risk | 15% attrition (33/219) at follow‐up. All those lost to follow‐up were treated as continuing smokers. |
| Selective reporting (reporting bias) | Low risk | Not apparent. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Biochemically validated with salivary thiocyanate in approximately a third of participants (n = 66), but no adjustment for misclassification. |
| Blinding of participants and personnel (performance bias) | High risk | Caregivers not blinded to this educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not stated. |
| Incomplete implementation | Unclear risk | No process evaluation. |
| Equal baseline characteristics in study arms | Unclear risk | Differences between study participants and refusals on variables available from the WIC record were relatively minor for important variables as were study group differences. |
| Contamination of control group | Low risk | Health educator, not UC provider, offering intervention. |
| Methods | 3‐armed randomised controlled trial of an intervention to support women to stop smoking and prevent relapse in pregnancy and postpartum. The study was conducted at the Group Health Cooperative of Puget Sound (Seattle, USA) (HMO), and Park‐Nicollet of Minnesota (USA), a multispecialty group practice. Years of data collection not stated. | |
| Participants | Inclusion criteria: Women who had completed the baseline survey, were < 20 weeks of pregnancy, were currently smoking or had smoked in the 30 days before pregnancy but had quit at the time of the baseline survey. Exclusion criteria: Unable to speak English. Recruitment: Women booked for a first prenatal visit were offered, by letter, study participation and unless they opted out were given a baseline telephone interview to assess smoking status. 9152 approached, 714 ineligible because of miscarriage, pregnancy termination, inability to speak English; 697 (8%) refused; 262 could not be reached by telephone after repeated attempts. 7479 (82%) completed survey. 1007/7479 (13%) were current smokers or recent quitters and were randomised: 897 participated (457 from Seattle, 440 from Minnesota), C = 297, I1 = 294, I2 = 306. Current smoker at baseline = 56% (C = 165, I1 = 176, I2 = 160). Baseline characteristics: Mean cigarettes/day before pregnancy = 14.9; Current mean cigarettes/day = 4.8. Mean age 27.7 years; Household income >= 30000 $US 67%; College graduates 17%; 88% white. Progress + coding: None. | |
| Interventions | There were 3 stages of change‐based interventions, all delivered by mail or telephone without involving prenatal care providers. Main intervention strategy: Counselling (multiple intervention) compared to less intensive intervention. Intervention 1 and 2 were only reported as combined outcomes in late pregnancy, and included in this review. Postpartum outcomes are reported by intervention group and combines smokers at baseline and spontaneous quitters. Intensity: Frequency (C = 2, I = 6); Duration (C = 1, I = 3). Intervention provided by dedicated project staff: Efficacy study. | |
| Outcomes | Self‐reported 7‐day point prevalence abstinence at 28 weeks' gestation (late pregnancy*), with sample biochemically validated. (combined I1 and I2), relapse prevention in late pregnancy (spontaneous quitters*), abstinence at 8 weeks (0‐5 months*), 6 months* (6‐11 months), and 12 months (12‐17 months) postpartum (combined baseline smokers and spontaneous quitters). Response rates were 92% at 28 weeks; 91% at 8 weeks' postpartum; 89% at 6 months postpartum; 87% at 12 months postpartum. A subsequent paper reports partner abstinence. | |
| Notes | Process evaluation describes participation in specific intervention components, including relapse prevention. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Not described. They were stratified by baseline smoking status. |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | Unclear risk | 110/1007 (11%) attrition. 88 miscarried and 22 were sent wrong intervention material and were excluded from analysis. 897 women included in final analysis. For self‐reported smoking status non‐respondents were treated as continuing smokers. |
| Selective reporting (reporting bias) | Unclear risk | Smoking outcomes only reported and only combined outcomes for abstinence at 28 weeks' gestation. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Salivary cotinine analysis. Salivary cotinine requested from all who reported abstaining for 7 days (< 20 ng/mL as cut‐off). 64%‐78% returned saliva samples and as there were no differences, outcomes reported are based on self‐reported status. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind providers and women to counselling intervention. |
| Blinding of outcome assessment (detection bias) | Low risk | All samples were analysed for cotinine at the American Health Foundation laboratory. The computer‐assisted telephone surveys were implemented by trained interviewers who had no role in intervention activities. |
| Incomplete implementation | Low risk | Over 90% in the intervention group recalled receiving the self‐help booklet, relapse prevention kit, counselling calls and newsletters. |
| Equal baseline characteristics in study arms | Unclear risk | There were some baseline differences reported in text. |
| Contamination of control group | Low risk | The intervention was delivered via mail and telephone without involving prenatal healthcare providers. |
| Methods | 3‐armed randomised controlled trial of counselling and social support interventions to support women to stop smoking during pregnancy and prevent relapse postpartum. The study was conducted in Womack Army Medical Centre at Fort Bragg in Feyettville, North Carolina (USA) from 1996 to 2001. | |
| Participants | Inclusion criteria: <= 20 weeks pregnant, >= 18 years of age, current smokers or recent quitters (i.e. were smokers in the 30 days prior to pregnancy but not smoking at intake), living with an intimate partner, and willing to have the partner contacted for participation in the study. Exclusion criteria: Not further specified. Recruitment: 6156 woman screened at first prenatal clinic appointments were sent introductory letters with a toll‐free number to call to decline contact. 997 pregnant smokers or recent quitters underwent further screening and 625 eligible women were randomised. Baseline characteristics: Active smokers (C = 91, I1 = 87, I2 = 89). Recent quitters (C = 107, I1 = 105, I2 = 104). Current mean cigarettes per day 6 (SD 5). 52% had a partner who smoked. Mean age 24 years; Household income >= 20000 $US 44%; > high school 52%; 96% married; 77% white. Progress + coding: none. | |
| Interventions | A: Control: 'UC' where women received provider advice to quit smoking at the first prenatal visit and were mailed the American Cancer Society’s self‐help guide, “Make Yours a Fresh Start Family,” written at the fifth‐grade reading level and designed for pregnant women. B: Intervention 1 (woman only): Control plus late pregnancy relapse‐prevention kit (a booklet and gift items) and 6 counselling calls (3 in pregnancy and 3 in postpartum) initiated by a health advisor, who used a standardised protocol based on MI techniques. All intervention contacts were completed by 4 months postpartum. Prenatal calls were timed to occur in each trimester and emphasised using self‐help materials to take stage‐appropriate steps towards cessation or to develop skills for remaining abstinent. Postpartum calls were timed to occur at monthly intervals and emphasised skills for remaining abstinent in the transition from pregnancy to parenting. C: Intervention 2 (partner‐assisted group): Woman only intervention plus a PA adjunct, in which the smoker described how her partner could be a coach to build and maintain the confidence she needed to quit smoking. An “It Takes Two” booklet and companion video were developed to guide couples in discussing support behaviours related to the woman’s smoking. Partners received 6 separate calls (3 in pregnancy and 3 postpartum) from the woman’s health advisor. These calls were made separately to the 2 individuals (pregnant woman and partner) and guided by a MI protocol similar to that used for counselling the women. The second and 4th calls to the couple focused on developing a written agreement regarding helpful partner support behaviours. Partners who smoked were given self‐help cessation guides, free nicotine patches if needed, and stage‐appropriate counselling. Main intervention strategy: Counselling (single intervention) compared to a less intensive intervention. Intervention 1 (arm b) compared to control in this study ID. Intensity: Frequency (C = 2, I = 4); Duration (C = 1, I = 4). Estimate as duration of calls not reported. Intervention provided by dedicated project staff: efficacy study. | |
| Outcomes | Self‐reported point prevalence abstinence at 28 weeks pregnancy among continuing smokers in pregnancy (late pregnancy*), relapse prevention at 28 weeks pregnancy among spontaneous quitters (late pregnancy*), continued abstinence of combined spontaneous quitters and smokers at 2 (0‐5*), 6 (6‐11*) and 12 (12‐17) months postpartum. Partner cessation and perceived support were reported. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Reported as 'stratified by smoking status, partners smoking status and partners willingness to be involved and randomised to one of 3 conditions'. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Unclear risk | 42 (7%) women who miscarried were excluded resulting in a sample of 583 (C = 198, I1 = 192, I2 = 193). An ITT approach was used, in which all randomised women (other than those who had miscarried) were included in the final analysis as continuing smokers. Dropout rates did not differ significantly across groups. |
| Selective reporting (reporting bias) | Low risk | All primary outcomes appear to be reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Self‐reported smoking status only. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants to social support intervention, requiring partner consent. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Partner participation decreased steadily throughout the trial. |
| Equal baseline characteristics in study arms | Low risk | Baseline characteristics appear equal. |
| Contamination of control group | Low risk | Care providers not providing intervention. |
| Methods | 3‐armed randomised controlled trial of counselling and social support interventions to support women to stop smoking during pregnancy and prevent relapse postpartum. The study was conducted in Womack Army Medical Centre at Fort Bragg in Feyettville, North Carolina (USA) from 1996 to 2001. | |
| Participants | Inclusion criteria: <= 20 weeks pregnant, >= 18 years of age, current smokers or recent quitters (i.e. were smokers in the 30 days prior to pregnancy but not smoking at intake), living with an intimate partner, and willing to have the partner contacted for participation in the study. Exclusion criteria: Not further specified. Recruitment: 6156 woman screened at first prenatal clinic appointments were sent introductory letters with a toll‐free number to call to decline contact. 997 pregnant smokers or recent quitters underwent further screening and 625 eligible women were randomised. Baseline characteristics: Active smokers (C = 91, I1 = 87, I2 = 89). Recent quitters (C = 107, I1 = 105, I2 = 104). Current mean cigarettes per day 6 (SD 5). 52% had a partner who smoked. Mean age 24 years; Household income >= 20000 $US 44%; > high school 52%; 96% married; 77% white. Progress + coding: none. | |
| Interventions | A: Control: 'UC' where women received provider advice to quit smoking at the first prenatal visit and were mailed the American Cancer Society’s self‐help guide, “Make Yours a Fresh Start Family,” written at the fifth‐grade reading level and designed for pregnant women. B: Intervention 1 (woman only): Control plus late pregnancy relapse‐prevention kit (a booklet and gift items) and 6 counselling calls (3 in pregnancy and 3 in postpartum) initiated by a health advisor, who used a standardised protocol based on MI techniques. All intervention contacts were completed by 4 months postpartum. Prenatal calls were timed to occur in each trimester and emphasised using self‐help materials to take stage‐appropriate steps towards cessation or to develop skills for remaining abstinent. Postpartum calls were timed to occur at monthly intervals and emphasised skills for remaining abstinent in the transition from pregnancy to parenting. C: Intervention 2 (partner‐assisted group): Woman only intervention plus a PA adjunct, in which the smoker described how her partner could be a coach to build and maintain the confidence she needed to quit smoking. An “It Takes Two” booklet and companion video were developed to guide couples in discussing support behaviours related to the woman’s smoking. Partners received 6 separate calls (3 in pregnancy and 3 postpartum) from the woman’s health advisor. These calls were made separately to the 2 individuals (pregnant woman and partner) and guided by a MI protocol similar to that used for counselling the women. The second and 4th calls to the couple focused on developing a written agreement regarding helpful partner support behaviours. Partners who smoked were given self‐help cessation guides, free nicotine patches if needed, and stage‐appropriate counselling. Main intervention strategy: Social support (multiple intervention) compared to a less intensive intervention. Intervention 2 (arm c) compared to control in this study ID. Intensity: Frequency (C = 2, I = 6); Duration (C = 1, I = 5). Estimate as duration of calls not reported. Intervention provided by dedicated project staff: efficacy study. | |
| Outcomes | Self‐reported point prevalence abstinence at 28 weeks pregnancy among continuing smokers in pregnancy (late pregnancy*), relapse prevention at 28 weeks pregnancy among spontaneous quitters (late pregnancy*), continued abstinence of combined spontaneous quitters and smokers at 2 (0‐5*), 6 (6‐11*) and 12*(12‐17) months postpartum. Partner cessation and perceived support were reported. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Reported as 'stratified by smoking status, partners smoking status and partners willingness to be involved and randomised to one of 3 conditions'. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Unclear risk | 42 (7%) women who miscarried were excluded resulting in a sample of 583 (C = 198, I1 = 192, I2 = 193). An ITT approach was used, in which all randomised women (other than those who had miscarried) were included in the final analysis as continuing smokers. Dropout rates did not differ significantly across groups. |
| Selective reporting (reporting bias) | Low risk | All primary outcomes appear to be reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Self‐reported smoking status only. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants to social support intervention, requiring partner consent. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Partner participation decreased steadily throughout the trial. |
| Equal baseline characteristics in study arms | Low risk | Baseline characteristics appear equal. |
| Contamination of control group | Low risk | Care providers not providing intervention. |
| Methods | 4‐armed cluster‐randomised trial (2 x 2) to support women to stop smoking in pregnancy and breastfeed postpartum. Study conducted in the lower North Island, New Zealand, with recruitment from June 1999 to September 2000. | |
| Participants | Inclusion criteria: The midwifery team was the unit of randomisation, which were stratified by locality and randomised into 1 of 4 groups. All midwives in selected localities in the lower north island were invited to take part. Midwives asked all pregnant women who had smoked at the time they conceived to take part in the study. Exclusion criteria: Not further specified. Recruitment: 93/121 (77%) midwives invited (from 62 midwifery teams), agreed to participate, and were randomised into 1 of 4 study arms (C = 23,I1 = 22,I2 = 22, I3 = 26). 61 midwives recruited women to the study (76%). 46/349 (13%) women approached declined to take part in the study, 6 were ineligible, and 297 were recruited (C = 60, I1 = 60, I2 = 69, I3 = 108). Baseline characteristics: Partner smoking (C = 50%, I1 = 47%, I2 = 62%, I3 = 49%). Mean age: C = 24.9, I1 = 26.1, I2 = 27.3, I3 = 25.1. Maori: C = 42%. I1 = 36%. I2 = 20%, I3 = 27%. Over 50% in receipt of community services card. Progress + coding: Low SES. | |
| Interventions | Intervention developed with provider input and detailed discussion of provider views included. A: Control: 'Usual' maternity care from a midwife, which ranged from asking about smoking, giving advice to quit and to providing more detailed smoking‐cessation advice. B: Intervention 1 (smoking education): Midwife training to implement education and support for smoking cessation and reduction. C: Intervention 2 (breastfeeding): Midwife training and support to implement education and support for breastfeeding for women who smoked. D: Intervention 3 (combined): Midwife training to implement smoking education and breastfeeding programmes. Smoking education included MI provided by a midwife (who was allocated an extra funded visit and given 4 hours training with a counsellor), flip‐chart, video‐tape. Main intervention strategy: Counselling (single intervention) compared to UC. Groups A and C compared to groups B and D in this review. Intensity: Frequency (C = 0, I = 2), Duration (C = 0, I = 2). UC intensity: F = 1, D = 1. Intervention provided by existing staff (midwives): Effectiveness study. | |
| Outcomes | Biochemically validated smoking cessation at 28 and 36 weeks' gestation* (late pregnancy), and 6 weeks and 4 months postpartum* (0‐5 months postpartum). Smoking reduction outcomes of self‐reported 'cut down a little' or 'cut down significantly' are not included in this review as outcomes unclear. Breastfeeding outcomes also reported. | |
| Notes | Design effect for clustering reported, so outcome figures used for adjusting figures in this review. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Random sequence generation using excel for each stratum. |
| Allocation concealment (selection bias) | Low risk | Group allocation by external statistician. |
| Incomplete outcome data (attrition bias) | Low risk | Missing data for most outcomes, 28% attrition for 4‐month postnatal follow‐up. However, all randomised women included in analysis in this review. |
| Selective reporting (reporting bias) | Unclear risk | Smoking status only reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Serum cotinine samples provided by 108 women. 17/19 self‐reported non‐smokers had cotinine levels consistent with non‐smoking, but outcomes not adjusted for misclassification. 15 ng/mL cut‐off level. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Not possible to blind midwives to allocation group. Women were not aware of midwife group allocation. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | There were problems with some midwives not recruiting any women to the study, but the degree of implementation among those women recruited is not reported. |
| Equal baseline characteristics in study arms | High risk | When compared with control group, women in the smoking group were older and less likely to be Maori. Also the number of women recruited to the combined group was much larger than the other groups, which suggests potential issues with recruitment. |
| Contamination of control group | Unclear risk | Cluster‐study design to avoid contamination. |
| Methods | A single‐blind, parallel‐group, randomised controlled trial to assess the VoorZorg nurse visitation programme, and its effects on smoking, pregnancy outcomes and breastfeeding, carried out in 20 different municipalities, the Netherlands between 2007 and 2009. | |
| Participants | Inclusion criteria: Age < 26 years, <= 28 weeks pregnancy with the first child, low educational level and some knowledge of the Dutch language. Women had to have at least 1 risk factor: no social support, previously or currently experiencing domestic violence, psychosocial symptoms, unwanted and/or unplanned pregnancy, financial problems, housing difficulties, no education and/or employment and alcohol and/or drug use. Exclusion criteria: Not stated. Recruitment: Women were actively recruited by GPs and midwives, with 460 pregnant women randomised (C = 223 I = 237). Baseline characteristics: Attempted to quit smoking (C = 80% I = 82%). Stopped smoking after aware of the pregnancy (C = 20% I = 13%). Mean age (C = 19.2 I = 19.5) Employed C = 28% I = 29%, Prevocational Education (C = 96% I = 94%) (rest primary school only). Progress + coding: Low SES due to inclusion criteria being presence of at least 1 risk factor. | |
| Interventions | Control: UC, which for pregnant women in the Netherlands includes maternal health care delivered by a midwife. Intervention: Women in the intervention group were offered,in addition to UC, approximately 10 home visits during pregnancy, 20 during the first year and 20 during the second life year of the child by trained, specialised VoorZorg nurses. According to the protocol, 6 domains were discussed during the home visits: (1) the health status of the mother, (2) the child's health and safety,(3) the personal development of the mother, (4) the role of the mother, (5) the mother's relation with her partner, family and friends and (6) the use of (health) care organisations. Main Intervention strategy: Maternal Health intervention with smoking cessation component: social support (single) vs UC Intensity: Frequency (C = 0, I = 6) Duration (C = 0, I = 4). Intervention provided by study staff: efficacy study | |
| Outcomes | Self‐reported abstinence in late pregnancy* (32 weeks of pregnancy), abstinence at 2 months post birth (0‐5 months pp)*, mean number of cigarettes smoked per day*, birthweight, prematurity, LBW (< 2500 g), weeks of gestation, adverse pregnancy outcomes, small for gestational age and breastfeeding. Birth outcomes not included in this review as other aspects of intervention other than smoking cessation may have contributed to these outcomes. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Participants were randomly assigned into the control or intervention group after being stratified by region and ethnicity by use of the computer‐generated list of random numbers. |
| Allocation concealment (selection bias) | Low risk | Randomisation was performed with a computer‐generated list, so assume researcher was blinded. |
| Incomplete outcome data (attrition bias) | Unclear risk | Last observation carried forward approach was conducted to replace missing data. |
| Selective reporting (reporting bias) | Low risk | All outcomes are reported. |
| Other bias | Unclear risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Cigarette smoking was assessed by self‐report measure. |
| Blinding of participants and personnel (performance bias) | High risk | Interviewers were blinded from allocation, however as the intervention was health education is was not feasible to blind women or providers. |
| Blinding of outcome assessment (detection bias) | Low risk | Interviewers were blinded at follow‐up. |
| Incomplete implementation | Low risk | Good implementation. |
| Equal baseline characteristics in study arms | Low risk | Baseline characteristics appeared to be equal. |
| Contamination of control group | Low risk | Main component of the intervention is home visitation. |
| Methods | Cluster‐randomised controlled trial to test the effectiveness of the ALA smoking in pregnancy intervention to support women to stop smoking in pregnancy. Study conducted in 11 private obstetric practices in Michigan and Upper Wisconsin (USA), with recruitment from August 1985 to June 1986. | |
| Participants | Inclusion criteria: 24 physicians in 11 private practices participated in the study (12 family physicians and 12 obstetricians). Study practices randomised into 'roughly equal groups'. Women smoking at first AN appointment, less than 28 weeks' gestation were recruited to study. Exclusion criteria: Not further specified. Recruitment: All women attending those clinics invited to participate. After giving informed consent, each woman was assigned a code number and had a questionnaire pack placed in her chart. 639 women screened (5 refusals), 206 smokers (32%), 69/209 had quit since becoming pregnant and 137 continuing smokers were included in the study (C = 70, I = 67). Baseline characteristics: Pre‐pregnancy mean cigarettes per day = 20; current mean cigarettes per day = 11. 98% white, 70% married, majority (80%) completed high school. Progress + coding: None. | |
| Interventions | Control: 3 counselling sessions with physician on risks, ashtrays removed from waiting rooms and staff asked not to smoke in front of patients. Intervention: Control plus (i) use of ALA materials (because you love your baby flip chart; because you love your baby packets, because you love your baby poster) (ii) encouragement to send off for materials (freedom from smoking manual), (iii) slide tape presentation at each women's first obstetrics visit. Main intervention strategy: Counselling (multiple intervention) compared to less intensive intervention. Intensity: Frequency (C = 3, I = 5), Duration (C = 1, I = 2). Intervention provided by existing staff (physicians): Effectiveness study. | |
| Outcomes | Self‐reported smoking abstinence at 32‐36 weeks' gestation (late pregnancy*) and first postpartum visit (timing not specified but assumed is standard 6 weeks pp visit), 0‐5 months pp*. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Stratified by size ‐ and then assigned by coin toss. |
| Allocation concealment (selection bias) | High risk | Allocation not concealed with coin toss randomisation. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition: 7 miscarriages (C = 4, I = 3), 2 therapeutic abortions (C = 0, I = 2), 11 moved (C = 6, I = 5) and 8 had an incomplete dataset (C = 4, I = 4). Those with incomplete dataset were re‐included as continuing smokers in this review (C = 60, I = 57). |
| Selective reporting (reporting bias) | Low risk | Primary outcomes appear to be reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | No biochemical validation of smoking status (self‐report only). |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind providers and women to educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | Exact rates not reported ‐ but 'only minor deviations' suggests very high implementation. |
| Equal baseline characteristics in study arms | Unclear risk | Not reported. |
| Contamination of control group | Low risk | Cluster‐randomised by clinic ‐ so unlikely to have ALA materials. |
| Methods | Randomised controlled trial of nurse telephone support, which aimed to reduce infants born LBW and preterm, and included advice on smoking. Study conducted in a community public clinic in the USA. Location and dates of data collection unclear. | |
| Participants | Inclusion criteria: Women with a preterm labour risk score of at least 7 on the Wake Forest University School of Medicine risk assessment tool; English‐speaking; access to telephone; 22‐32 weeks' gestation. Exclusion criteria: Not further specified. Recruitment: 1850/3127 (59.2%) eligible women contacted. 1554 (84%) agreed to participate and were randomised (C = 779, I = 775). Baseline characteristics: 21.2% (n = 253) identified themselves as smokers. Black = 1113, White or other = 320. Progress + coding: Not coded for this review as outcomes unable to be included. | |
| Interventions | Control: Booklet about preventing preterm labour, available in regular clinic. $10 gift certificate for completing questionnaire at 34 weeks' gestation. Intervention: As control + instruction about signs of preterm labour, nurse telephone call schedule. 3 telephone calls per week which addressed: assessment of health status (including cigarette use); recommendations; and discussion of additional issues important to mother. $25 gift certificate at 37 weeks or after the birth of their baby if they returned their assessment and remained in contact with the nurse by telephone. Main intervention strategy: Maternal health intervention with smoking component: Counselling (single intervention) compared to UC. Intensity: Not coded as outcomes not able to be included. | |
| Outcomes | LBW and preterm births. Outcomes not included in study as unclear what proportion of outcomes were related to smokers. Furthermore, other aspects of the intervention (other than smoking cessation) may have impacted on perinatal outcomes so not included in this review. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Random assignment by biostatistician using computer randomisation table. |
| Allocation concealment (selection bias) | Low risk | Opaque sealed envelopes. |
| Incomplete outcome data (attrition bias) | Unclear risk | 7.8% attrition due to moving or multiple pregnancies, leaving 1433 included in birth outcome analysis. I = 718, C = 715. |
| Selective reporting (reporting bias) | Unclear risk | Smoking rates not reported, though not the primary aim of study. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Self‐reported smoking, but not reported as an outcome in this study. |
| Blinding of participants and personnel (performance bias) | High risk | Women and providers not able to be blinded to counselling intervention. |
| Blinding of outcome assessment (detection bias) | Low risk | Outcome assessor blinded. |
| Incomplete implementation | Low risk | Process evaluation not reported. |
| Equal baseline characteristics in study arms | Low risk | No significant differences between groups. |
| Contamination of control group | Unclear risk | Telephone intervention so unlikely calls were made to wrong women. |
| Methods | Cluster‐randomised trial of self‐help booklets to support women to stop smoking and prevent relapse in pregnancy. Study conducted in 3 NHS hospital trusts in England (UK), with recruitment from May 1998 to July 2000. | |
| Participants | Inclusion criteria: Midwives were the unit of randomisation. Women attending first visit; >= 16 years; < 17 weeks' gestation; literate in English were eligible. Smokers counted as those who reported "I smoke now", "I smoke now but have cut down since I thought I might be pregnant", or "I have stopped smoking since I thought I might be pregnant". Exclusion criteria: Not further specified. Recruitment: All 128 community midwives in 3 trusts agreed to participate and were randomly allocated to 6 strata (C = 64, I = 64). 3 midwives went on maternity leave and did not recruit any women (C = 64, I = 61). 8586 women screened and 1527/1803 (85%) eligible women consented to participate (C = 803, I = 724). Baseline characteristics: Current smokers: C = 97, I = 97; Current but reduced since pregnancy: C = 464, I = 445 (All current smokers C = 561, I = 542); Recent quitters: C = 242, I = 182. Mean cigarettes per day before pregnancy: C = 15.1, I = 16. Mean cigarettes per day at baseline C = 5.5, I = 6.4. Maternal age: C = 26.7, I = 27.2. Left full time education by 16 years: C = 63.6%, I = 61%. | |
| Interventions | Control: Midwives continued to give routine advice according to usual practice. Main intervention strategy: Counselling (single intervention) compared to UC. Intensity: Frequency: (C = 0, I = 4), Duration (C = 0, I = 1). UC intensity: F = 1, D = 1. Intervention provided by existing staff: Effectiveness study. | |
| Outcomes | 7‐day point prevalence abstinence at 26 weeks' gestation (late pregnancy*), with 94% validated by urine cotinine (80 ng/mL). Self‐reported mean cigarettes per day in late pregnancy*. Relapse prevention for recent quitters not reported separately so outcomes for smokers and recent quitters are combined in this analysis. | |
| Notes | Reported intracluster correlation of 0.031 used to adjust outcome data for inclusion in outcome tables. Sample size justification. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Stratified random allocation by computer‐generated random numbers. 118 midwives stratified according to workload and randomly allocated to provide intervention or control care. |
| Allocation concealment (selection bias) | Unclear risk | No information. |
| Incomplete outcome data (attrition bias) | Unclear risk | 92/1527 (6%) excluded from analysis due to miscarriage or termination (C = 36, I = 40), stillbirth or neonatal death (C = 9, I = 6)‐not included as unable to separate, preterm birth (C = 1). Those lost to further follow‐up (C = 50, I = 68) were included as continuing smokers in this review, leaving 1435 (C = 757, I = 678). |
| Selective reporting (reporting bias) | High risk | Outcomes not reported separately for baseline smokers and spontaneous quitters. |
| Other bias | Unclear risk | Some unequal recruitment in each arm |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Urinary cotinine levels analysed (cut‐off 60 ng/mL and 100 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Midwives randomised. Educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Outcome assessment blinding not reported. However, follow‐up rates were high in both groups, and all data coding and cleaning was undertaken blind to treatment allocation. |
| Incomplete implementation | High risk | Detailed qualitative and quantitative process analysis of participants' and midwives' views of the intervention, which suggested poor implementation in some areas. |
| Equal baseline characteristics in study arms | High risk | There were some differences between the 2 treatment groups at baseline, most notably in the numbers of women who had stopped smoking before the booking appointment and in the quantity of cigarettes consumed before the pregnancy and at the time of booking. |
| Contamination of control group | High risk | Some concerns about contamination of control group reported. |
| Methods | Pilot randomised controlled trial to evaluate the feasibility, acceptability and potential effectiveness of tailored leaflets and SMS text messaging self‐help intervention (MiQuit) to support women to stop smoking in pregnancy. Study conducted in 7 National Health Service Trusts in the south east, east and north east of England (UK), with recruitment between December 2008 and October 2009. | |
| Participants | Inclusion criteria: Pregnant women less than 21 weeks' gestation, 16 years of age and over, smoked >= 7 cigarettes per week, owned or had regular use of a mobile phone, and could understand written English. Exclusion criteria: Not further specified. Recruitment: 625 women were referred by midwives to the study and 207/512 (40%) eligible women agreed to participate and were randomised to the study (C = 105, I = 102). Baseline characteristics: Cigarettes per day before pregnancy and at enrolment reported by 6 categories and equal in both arms. Majority (over 60%) 11‐20 cigarettes/day before pregnancy and approximately 50% 4‐10 cigarettes/day at enrolment. Median age 26‐27 years; 16% did not complete high school; 100% white. Progress + coding: None. | |
| Interventions | Control: Participants received a non‐tailored self‐help leaflet, which matched the tailored leaflet in format and style, and the same assessment texts as MiQuit participants but no intervention texts. Intervention:Participants receive MiQuit tailored self‐help leaflet by post. Thereafter, automated tailored text message component of intervention is initiated. 80 texts sent out over 11 weeks. MiQuit participants could also request instant response supportive texts at any time of the day. Main intervention strategy: Health education (multiple intervention) compared to less intensive intervention. Intensity: Frequency: (C = 2, I = 6), Duration: (C = 1, I = 1). Technological intervention: Unclear whether efficacy or effectiveness study | |
| Outcomes | Biochemically validated 7‐day point prevalence at 3‐month follow‐up (late pregnancy)*, self‐reported 4‐week point prevalence, initiation and frequency of quit attempts and 7‐day point prevalence at 3 and 7 weeks after enrolment; Self‐efficacy (5‐point scale), acceptability measures. | |
| Notes | Process evaluation showed 98% intervention and 89% control participants received the leaflet and 87% intervention participants reported reading text messages at least once. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Generation of the randomisation tables and allocation of participants were implemented in a computer programme and managed by SS who had no contact with participants or involvement in data collection or entry. |
| Allocation concealment (selection bias) | Low risk | 'The allocation sequence was concealed from other members of the research team, midwives, and participants' (p570) |
| Incomplete outcome data (attrition bias) | Unclear risk | Drop‐outs due to miscarriage or stillbirth were excluded from the analysis (I = 6, C = 3). Reported as combined figure. 11% further attrition for other reasons (I = 10, C = 13), were included in analysis as continuing smokers (C = 96, I = 102). |
| Selective reporting (reporting bias) | Low risk | All primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation of self‐reported smoking cessation with salivary cotinine (< 13 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Women unlikely to be blinded to educational intervention. |
| Blinding of outcome assessment (detection bias) | Low risk | 'FN undertook data collection and was blinded to group allocation until all data had been collected.' (p570). |
| Incomplete implementation | Low risk | 90% MiQuit participants reported reading all the leaflet at least once. |
| Equal baseline characteristics in study arms | Low risk | There were no differences between trial arms on baseline variables except that more participants in the control arm had smoked in a previous pregnancy (difference adjusted for in analyses). |
| Contamination of control group | Low risk | Technological intervention so low risk of contamination between study arms. |
| Methods | 4‐armed randomised controlled trial which aimed to improve the uptake of prenatal care and pregnancy outcomes (especially LBW), and included advice about smoking. Study conducted in a semi‐rural county of New York State (USA), with recruitment between April 1978 and September 1980. | |
| Participants | Inclusion criteria: Pregnant women with no prior live births + any of the following: < 19 years; single; low socio‐economic status, and any other women with no prior live births who wished to participate in the program. Exclusion criteria: > 25 weeks' gestation (though some were enrolled at 25‐29 weeks). Recruitment: Through private obstetricians' offices, planned parenthood, public schools health department AN clinics and other health and human service agencies. 10% of target population entered prenatal care too late, 10% were not referred from private care. 500 women were interviewed and 400 enrolled (80%). Families were stratified by marital status, race, and 7 geographic regions (C = 90, I1 = 94, I2 = 100, I3 = 116). 141 smokers (C = 64, I = 77). Baseline characteristics: Mean cigarettes per day at intake: C = 6.94, I = 7.65. 47% < 19 years old, 62% single, 61% low SES (15% had none of these factors). Non‐Whites (46) excluded because too few; serious maternal or fetal conditions (20) excluded. Progress + coding: Low SES. | |
| Interventions | Control: Health and developmental screening of the baby at 12 and 24 months; Main intervention strategy: Maternal health intervention with smoking cessation component: Social support (tailored intervention) compared to UC. Intervention 2 and 3 (nurse‐visiting arms) compared to control and intervention 1 arms (no nurse visiting) in this review. Intervention provided by dedicated study team: Efficacy study. | |
| Outcomes | Cotinine levels taken in a subsample (n = 116), but no women reported smoking cessation at 32 weeks' gestation (late pregnancy)*. Mean cigarettes per day at 32 weeks (late pregnancy*). No mean cotinine levels reported for inclusion. Self‐reported reduction in cigarettes, but not reported as a mean for inclusion in this review. Birth outcomes were not included as aspects of the intervention, other than smoking cessation, may potentially improve birth outcomes. | |
| Notes | SDs for mean cigarettes per day were not reported, therefore we calculated a mean SD from 14 studies with available mean cigarette SDs (6.5) to include in this review, as recommended by the cochrane handbook | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | No information provided. |
| Allocation concealment (selection bias) | Unclear risk | Not specified. |
| Incomplete outcome data (attrition bias) | Unclear risk | 6.5% attrition (C = 12, I = 14) due to moving or miscarriage. However outcomes for 307/400 women only reported. Outcomes for all smokers at intake reported. |
| Selective reporting (reporting bias) | Low risk | Detailed range of outcomes reported. |
| Other bias | Unclear risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Serum cotinine analysis on subsample of 116. No self‐reported cessation to validate. |
| Blinding of participants and personnel (performance bias) | High risk | Home visitation programme. Blinding of participants and personnel not viable. |
| Blinding of outcome assessment (detection bias) | Low risk | The interviewers and medical record reviewers hired by the research project did not know to which treatment the women had been assigned. |
| Incomplete implementation | Unclear risk | Not reported. |
| Equal baseline characteristics in study arms | High risk | Women assigned a nurse had less social support. |
| Contamination of control group | Low risk | Home visits. |
| Methods | 3‐armed randomised controlled trial of home visiting during pregnancy by paraprofessionals and nurses to improve maternal and child health, and included advice about smoking. The study was conducted in 21 prenatal clinics in Denver (USA) from March 1994 to June 1995. | |
| Participants | Inclusion criteria: Pregnant women with no previous live births and either qualified for Medicaid or had no private medical insurance. Exclusion criteria: Not further specified. Recruitment: By written invite, and were not required to respond. 735/1135 eligible women participated in the study, 70 of whom were smokers (C = 25, I1 = 21,I2 = 24). Baseline characteristics: Not reported among smoking subgroup. | |
| Interventions | A: Control: Developmental screening and referral services for children at 6, 12, 15, 21 and 24 months old. B: Intervention 1 (Paraprofessional): Screening and referral plus paraprofessional home visiting for first 2 years of infants life. Aimed to improve maternal and fetal health, improve health and development of child, and enhance parents personal development. C: Intervention 2 (Nurse): Screening and referral plus nurse home visiting for first 2 years of infants life. Aimed to improve maternal and fetal health, improve health and development of child, and enhance parents personal development. Main intervention strategy: Maternal health intervention with smoking component: Social support (single) vs less intensive intervention. Not coded or compared in this review as outcomes unable to be included. | |
| Outcomes | Outcomes not able to be included in meta‐analysis, as only mean reduction in cotinine reported. See Table 2 for outcome summary. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer‐generated random sequence. |
| Allocation concealment (selection bias) | Unclear risk | Allocation conducted in separate data centre. |
| Incomplete outcome data (attrition bias) | Unclear risk | Unclear whether all randomised smokers were included in cotinine analysis. |
| Selective reporting (reporting bias) | High risk | Smoking cessation rates not reported, but are not a primary outcome of this study. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Unclear whether all randomised women included in cotinine analysis. |
| Blinding of participants and personnel (performance bias) | High risk | Providers and women not able to be blinded as social support intervention. |
| Blinding of outcome assessment (detection bias) | Low risk | Outcome assessors blinded to allocation. Study team unaware of allocation, unless the participant told them. |
| Incomplete implementation | Low risk | Paraprofessionals completed an average of 6.3 visits and nurses an average of 6.5 visits. |
| Equal baseline characteristics in study arms | Unclear risk | Baseline characteristics of smokers not reported. But treatment groups similar with 'few exceptions'. |
| Contamination of control group | Low risk | Home visits. |
| Methods | 4‐armed (2 x 2 factorial design) randomised controlled trial of a computer‐delivered brief intervention (CD‐5As) and incentives to support women to stop smoking in pregnancy. The study was conducted in 4 prenatal care clinics in Detroit, MI (USA) with recruitment from July 2008 to November 2009, and final evaluation completed by January 2010. | |
| Participants | Inclusion criteria: Pregnant women aged 18 years or older, being no further than 27 weeks' gestation, and reporting smoking in the past week. Exclusion criteria: Unable to understand spoken English. Recruitment: 1317 women were screened while in the clinic waiting area. 110/114 (96%) eligible women provided consent and were randomised (C = 26, I1: CD‐5As only = 26, I2: CM‐Lite only = 28, I3 = CM‐Lite + CD 5As = 30). Baseline characteristics: Average cigarettes per day in week prior to recruitment: mean = 8 (SD 8.2). 70% lived with a smoker. 52.8% had a Fagerstrom score >= 4 (nicotine dependence). Mean age 27.9 (6.4); 90% Black. K6 emotional distress 14.9. Progress + coding: Low SES and ethnic minority. | |
| Interventions | A: Control: UC from prenatal care from care‐providers without influence from the research team. B: Intervention 1 CD‐5As only: Computer‐delivered brief intervention designed to be consistent with '5As national guidelines (USA)' (Ask, Advise, Assess, Assist, Arrange) and—for those who are unwilling to set a quit goal—the 5Rs (with steps involving the highlighting of Relevance, Risks, Rewards, Roadblocks, and Repetition). The 'Advice' included a 5‐min video featuring a male black obstetrician and 3 testimonials from women of varying race, which was direct but designed to be positive and frame the benefits of quitting rather than the risks of smoking. C: Intervention 2 CM‐Lite (incentives) only: This modified version of 'contingency management' was designed for use with non‐treatment‐seeking persons in a healthcare setting with the presumption of (a) at least occasional repeat office visits and (b) limited ability of medical staff to monitor participants or participate in training. Thus, no proactive tracking was provided in CM‐Lite: It was designed to be patient‐initiated, with staff checking eligibility if and when a patient asks to have their smoking status verified rather than relying on staff to check the eligibility of every incoming patient. CM‐Lite calls for testing at prenatal care visits only and unlimited incentivisation attempts, but only up to a maximum of 5 episodes of reinforcement (in the form of retail gift cards worth $50), only at prenatal clinic visits, each at least a week apart. CM‐Lite was delivered with the help of a website which facilitated the process of verifying eligibility of participants, provided step‐by‐step guidance in how to conduct a valid test for urinary cotinine, recorded the results of testing, and provided a record of all incentive attempts and their outcome. D: Intervention 3 CD‐5As + CM‐Lite combined. Main intervention strategy: Health education (single intervention) compared to UC. Intervention 1 + 3 (arms B + D) compared with control + intervention 2 (arms A + C) in this study ID to capitalise on factorial design to assess effect of health education. Intensity: Frequency (C = 0, I = 1), Duration (C = 0, I = 1). Technological intervention: unclear whether delivered by existing staff (Effectiveness study) or dedicated project staff (efficacy study). | |
| Outcomes | Biochemically validated abstinence (cotinine; 7‐day point prevalence + CO; and 30‐day abstinence) at 10‐week follow‐up (late pregnancy*). We have used cotinine validated outcomes in this review as it is more comparable with other studies in this review where only 1 validation method is reported. Secondary help‐seeking (Quitline), self‐reported sustained abstinence in the past 30 days, Fagerstrom Test for nicotine dependence; Baseline K6 measure of overall emotional distress; Acceptability (satisfaction‐related measures). | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer randomisation of all participants into either CD‐5As or time control conditions and after participants completed all computer‐delivered content—research assistants used a predetermined list of computer‐generated random numbers to further randomise half of all participants into the CM condition. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition 16/110 (14.5%) lost to follow‐up. All analyses were on an ITT basis that analysed participants as allocated to condition without respect to completion of treatment elements. Only 2 women who withdrew due to miscarriage (1 in combined arm and 1 in UC arm) were excluded from the analysis in this review. A = 25, B = 26, C = 28, D = 29 (n = 108 included). |
| Selective reporting (reporting bias) | Low risk | All primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Self‐reported 7‐day abstinence biochemically validated with expired CO (< 4 ppm) and urinary cotinine (< 100 ng/mL)*. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Each intervention involved the same level of interaction with the computer and took the same approximate amount of time, thus keeping research assistants blind to computer‐delivered intervention condition. Not feasible to blind participants. |
| Blinding of outcome assessment (detection bias) | Unclear risk | It is not stated whether outcome assessors were blinded. |
| Incomplete implementation | Unclear risk | Process evaluation showed all participants assigned to CD‐5As condition completed the items and evaluations and gave high satisfaction ratings. Of the participants assigned to CM‐Lite only 37.9% initiated testing of at least 1 urine sample (mean 3.7, SD 1.9). |
| Equal baseline characteristics in study arms | Low risk | There were no significant differences between conditions on any of the baseline characteristics examined, although 1 variable (minority vs non‐minority race) was below P = .10 and so was controlled for in subsequent analyses. |
| Contamination of control group | Low risk | The risk of contamination between study arms is low as interventions are all provided via technology. |
| Methods | 4‐armed (2 x 2 factorial design) randomised controlled trial of a computer‐delivered brief intervention (CD‐5As) and incentives to support women to stop smoking in pregnancy. The study was conducted in 4 prenatal care clinics in Detroit, MI (USA) with recruitment from July 2008 to November 2009, and final evaluation completed by January 2010. | |
| Participants | Inclusion criteria: Pregnant women aged 18 years or older, being no further than 27 weeks' gestation, and reporting smoking in the past week. Exclusion criteria: Unable to understand spoken English. Recruitment: 1317 women were screened while in the clinic waiting area. 110/114 (96%) eligible women provided consent and were randomised (C = 26, I1: CD‐5As only = 26, I2: CM‐Lite only = 28, I3 = CM‐Lite + CD 5As = 30). Baseline characteristics: Average cigarettes per day in week prior to recruitment: mean = 8 (SD 8.2). 70% lived with a smoker. 52.8% had a Fagerstrom score >= 4 (nicotine dependence). Mean age 27.9 (6.4); 90% Black. K6 emotional distress 14.9. Progress + coding: Low SES and ethnic minority. | |
| Interventions | A: Control: UC from prenatal care from care‐providers without influence from the research team. B: Intervention 1 CD‐5As only: Computer‐delivered brief intervention designed to be consistent with '5As national guidelines (USA)' (Ask, Advise, Assess, Assist, Arrange) and—for those who are unwilling to set a quit goal—the 5Rs (with steps involving the highlighting of Relevance, Risks, Rewards, Roadblocks, and Repetition). The 'Advice' included a 5‐min video featuring a male black obstetrician and 3 testimonials from women of varying race, which was direct but designed to be positive and frame the benefits of quitting rather than the risks of smoking. C: Intervention 2 CM‐Lite (incentives) only: This modified version of 'contingency management' was designed for use with non‐treatment‐seeking persons in a healthcare setting with the presumption of (a) at least occasional repeat office visits and (b) limited ability of medical staff to monitor participants or participate in training. Thus, no proactive tracking was provided in CM‐Lite: It was designed to be patient‐initiated, with staff checking eligibility if and when a patient asks to have their smoking status verified rather than relying on staff to check the eligibility of every incoming patient. CM‐Lite calls for testing at prenatal care visits only and unlimited incentivisation attempts, but only up to a maximum of 5 episodes of reinforcement (in the form of retail gift cards worth $50), only at prenatal clinic visits, each at least a week apart. CM‐Lite was delivered with the help of a website which facilitated the process of verifying eligibility of participants, provided step‐by‐step guidance in how to conduct a valid test for urinary cotinine, recorded the results of testing, and provided a record of all incentive attempts and their outcome. Intervention 3 CD‐5As + CM‐Lite combined. Main intervention strategy: Incentives (tailored intervention) compared to UC. Intervention 2 compared with control in this study ID. Intensity: Frequency (C = 0, I = 5), Duration (C = 0, I = 1). Technological intervention: unclear whether delivered by existing staff (Effectiveness study) or dedicated project staff (efficacy study). | |
| Outcomes | Biochemically validated abstinence (cotinine; 7‐day point prevalence + CO; and 30‐day abstinence) at 10‐week follow‐up (late pregnancy*). We have used cotinine validated outcomes in this review as it is more comparable with other studies in this review where only 1 validation method is reported. Secondary help‐seeking (Quitline), self‐reported sustained abstinence in the past 30 days, Fagerstrom Test for nicotine dependence; Baseline K6 measure of overall emotional distress; Acceptability (satisfaction‐related measures). | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer randomisation of all participants into either CD‐5As or time control conditions and after participants completed all computer‐delivered content—research assistants used a predetermined list of computer‐generated random numbers to further randomise half of all participants into the CM condition. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition 16/110 (14.5%) lost to follow‐up. All analyses were on an ITT basis that analysed participants as allocated to condition without respect to completion of treatment elements. Only 2 women who withdrew due to miscarriage (one in combined arm and 1 in UC arm) were excluded from the analysis in this review. A = 25, B = 26, C = 28, D = 29 (n = 108 included). |
| Selective reporting (reporting bias) | Low risk | All primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Self‐reported 7‐day abstinence biochemically validated with expired CO (< 4 ppm) and urinary cotinine (< 100 ng/mL)*. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Each intervention involved the same level of interaction with the computer and took the same approximate amount of time, thus keeping research assistants blind to computer‐delivered intervention condition. Not feasible to blind participants. |
| Blinding of outcome assessment (detection bias) | Unclear risk | It is not stated whether outcome assessors were blinded. |
| Incomplete implementation | Unclear risk | Process evaluation showed all participants assigned to CD‐5As condition completed the items and evaluations and gave high satisfaction ratings. Of the participants assigned to CM‐Lite only 37.9% initiated testing of at least 1 urine sample (mean 3.7, SD 1.9). |
| Equal baseline characteristics in study arms | Low risk | There were no significant differences between conditions on any of the baseline characteristics examined, although 1 variable (minority vs non‐minority race) was below P = .10 and so was controlled for in subsequent analyses. |
| Contamination of control group | Low risk | The risk of contamination between study arms is low as interventions are all provided via technology. |
| Methods | 4‐armed (2 x 2 factorial design) randomised controlled trial of a computer‐delivered brief intervention (CD‐5As) and incentives to support women to stop smoking in pregnancy. The study was conducted in 4 prenatal care clinics in Detroit, MI (USA) with recruitment from July 2008 to November 2009, and final evaluation completed by January 2010. | |
| Participants | Inclusion criteria: Pregnant women aged 18 years or older, being no further than 27 weeks' gestation, and reporting smoking in the past week. Exclusion criteria: Unable to understand spoken English. Recruitment: 1317 women were screened while in the clinic waiting area. 110/114 (96%) eligible women provided consent and were randomised (C = 26, I1: CD‐5As only = 26, I2: CM‐Lite only = 28, I3 = CM‐Lite + CD 5As = 30). Baseline characteristics: Average cigarettes per day in week prior to recruitment: mean = 8 (SD 8.2). 70% lived with a smoker. 52.8% had a Fagerstrom score >= 4 (nicotine dependence). Mean age 27.9 (6.4); 90% Black. K6 emotional distress 14.9. Progress + coding: Low SES and ethnic minority. | |
| Interventions | A: Control: UC from prenatal care from care‐providers without influence from the research team. B: Intervention 1 CD‐5As only: Computer‐delivered brief intervention designed to be consistent with '5As national guidelines (USA)' (Ask, Advise, Assess, Assist, Arrange) and—for those who are unwilling to set a quit goal—the 5Rs (with steps involving the highlighting of Relevance, Risks, Rewards, Roadblocks, and Repetition). The 'Advice' included a 5‐min video featuring a male black obstetrician and 3 testimonials from women of varying race, which was direct but designed to be positive and frame the benefits of quitting rather than the risks of smoking. C: Intervention 2 CM‐Lite (incentives) only: This modified version of 'contingency management' was designed for use with non‐treatment‐seeking persons in a healthcare setting with the presumption of (a) at least occasional repeat office visits and (b) limited ability of medical staff to monitor participants or participate in training. Thus, no proactive tracking was provided in CM‐Lite: It was designed to be patient‐initiated, with staff checking eligibility if and when a patient asks to have their smoking status verified rather than relying on staff to check the eligibility of every incoming patient. CM‐Lite calls for testing at prenatal care visits only and unlimited incentivisation attempts, but only up to a maximum of 5 episodes of reinforcement (in the form of retail gift cards worth $50), only at prenatal clinic visits, each at least a week apart. CM‐Lite was delivered with the help of a website which facilitated the process of verifying eligibility of participants, provided step‐by‐step guidance in how to conduct a valid test for urinary cotinine, recorded the results of testing, and provided a record of all incentive attempts and their outcome. D: Intervention 3 CD‐5As + CM‐Lite combined. Main intervention strategy: Incentives (multiple intervention) compared to UC. Intervention 3 compared with control in this study ID. Intensity: Frequency (C = 0, I = 5), Duration (C = 0, I = 1). UC intensity unclear: F = 0, D = 0. Technological intervention: unclear whether delivered by existing staff (Effectiveness study) or dedicated project staff (efficacy study). | |
| Outcomes | Biochemically validated abstinence (cotinine; 7‐day point prevalence + CO; and 30‐day abstinence) at 10‐week follow‐up (late pregnancy*). We have used cotinine validated outcomes in this review as it is more comparable with other studies in this review where only 1 validation method is reported. Secondary help‐seeking (Quitline), self‐reported sustained abstinence in the past 30 days, Fagerstrom Test for nicotine dependence; K6 measure of overall emotional distress; Acceptability (satisfaction‐related measures). | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer randomisation of all participants into either CD‐5As or time control conditions and after participants completed all computer‐delivered content—research assistants used a predetermined list of computer‐generated random numbers to further randomise half of all participants into the CM condition. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition 16/110 (14.5%) lost to follow‐up. All analyses were on an intent‐to‐treat basis that analysed participants as allocated to condition without respect to completion of treatment elements. Only 2 women who withdrew due to miscarriage (one in combined arm and 1 in UC arm) were excluded from the analysis in this review. A = 25, B = 26, C = 28, D = 29 (n = 108 included). |
| Selective reporting (reporting bias) | Low risk | All primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Self‐reported 7‐day abstinence biochemically validated with expired CO (< 4 ppm) and urinary cotinine (< 100 ng/mL)*. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Each intervention involved the same level of interaction with the computer and took the same approximate amount of time, thus keeping research assistants blind to computer‐delivered intervention condition. Not feasible to blind participants. |
| Blinding of outcome assessment (detection bias) | Unclear risk | It is not stated whether outcome assessors were blinded. |
| Incomplete implementation | Unclear risk | Process evaluation showed all participants assigned to CD‐5As condition completed the items and evaluations and gave high satisfaction ratings. Of the participants assigned to CM‐Lite only 37.9% initiated testing of at least 1 urine sample (mean 3.7, SD 1.9). |
| Equal baseline characteristics in study arms | Low risk | There were no significant differences between conditions on any of the baseline characteristics examined, although 1 variable (minority vs non‐minority race) was below P = .10 and so was controlled for in subsequent analyses. |
| Contamination of control group | Low risk | The risk of contamination between study arms is low as interventions are all provided via technology. |
| Methods | This cluster‐randomised controlled trial (Programme C) was part of a larger programme carried out by the Dutch Healthcare Inspectorate which aimed to improve the provision of smoking‐cessation counselling to pregnant women by primary care midwives. | |
| Participants | Inclusion criteria: Not stated. Exclusion criteria: Any practices that had a large part of the staff and owner changed Recruitment: 14 intervention and 38 control practices. Baseline characteristics: Not stated. Progress + coding: None. | |
| Interventions | Control: Nothing implemented. Intervention: Intervention involved a site visit to improve provider provision of smoking cessation services (outcome). The supervision programme consisted of 3 elements: announcement of a deadline by which changes must be made (Programme A), assessments with questionnaires and personal report (Programme B) and assessments with site visits and personal report, which was the Randomised Controlled Trial (Programme C). Main Intervention strategy: Other (dissemination) v UC Progress plus coding: None and not included. | |
| Outcomes | No smoking outcomes reported. Only provision of smoking cessation services by providers. See Table 2 for summary of results. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Intervention (project C) aimed at changing provider practice (outcomes) so no information on pregnant smokers provided. |
| Allocation concealment (selection bias) | Unclear risk | Intervention (project C) aimed at changing provider practice (outcomes) so no information on pregnant smokers provided. |
| Incomplete outcome data (attrition bias) | Unclear risk | Intervention (project C) aimed at changing provider practice (outcomes) so no information on pregnant smokers provided. |
| Selective reporting (reporting bias) | Unclear risk | Intervention (project C) aimed at changing provider practice (outcomes) so no information on pregnant smokers provided. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | No smoking outcomes reported, so not applicable. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Intervention (project C) aimed at changing provider practice (outcomes) so no information on pregnant smokers provided. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Intervention (project C) aimed at changing provider practice (outcomes) so no information on pregnant smokers provided. |
| Incomplete implementation | Unclear risk | Intervention (project C) aimed at changing provider practice (outcomes) so no information on pregnant smokers provided. |
| Equal baseline characteristics in study arms | Unclear risk | Intervention (project C) aimed at changing provider practice (outcomes) so no information on pregnant smokers provided. |
| Contamination of control group | Unclear risk | Intervention (project C) aimed at changing provider practice (outcomes) so no information on pregnant smokers provided. |
| Methods | Randomised controlled trial of counselling interventions to support women to stop smoking in pregnancy. Study conducted in a public AN clinic in Melbourne, Victoria, Australia. Data collected from April 1994 to June 1996. | |
| Participants | Inclusion criteria: Women who identified as "current smokers" at their first AN visit at approximately 12 weeks' gestation ("even a puff in the last 7 days"). Exclusion criteria: > 20 weeks' gestation; twin pregnancy; not literate in English; drug dependency. Recruitment: 9193 women screened, 1942 (21%) current smokers and 625 (7%) spontaneous quitters (not included in study but described in Panjari 1997). 1013/1942 smokers (52%) agreed to participate (929 refused or not eligible) and were randomised (C = 537, I = 476). Mean age 26 years. Progress + coding: Low SES as authors note mostly low income women. | |
| Interventions | Control: UC, which included advice at the discretion of the caregiver, and 0 pamphlet "Smoking & Pregnancy" distributed during a group pregnancy information session. Intervention: As for the control group plus 4 counselling sessions by a midwife specifically trained and employed to provide smoking cessation counselling, using CBT. Sessions included video presentation, interactive discussion and strong verbal messages. These were followed up with a 5‐ to 10‐min personalised counselling session. Main intervention strategy: Counselling (single intervention) compared to UC. Intensity: Frequency (C = 0, I = 3), Duration (C = 0, I = 3). UC intensity: F = 1, D = 1. Intervention provided by dedicated project staff: efficacy study. | |
| Outcomes | Self‐reported smoking cessation biochemically validated with urine cotinine at 36 weeks' gestation (late pregnancy*), 6 weeks postpartum (0‐5 months)*, and 6 months (6‐11 months*) postpartum*. Preterm births*, mean birthweight*, proportion LBW* (< 2500 g). Reduction in mean cigarettes/day* and mean urinary cotinine levels*. Breastfeeding at 6 weeks and 6 months postpartum. General health assessment at first visit and 36 weeks. General health questionnaire (including stress and depression measurement) at baseline and end of pregnancy but data not reported. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | No information. |
| Allocation concealment (selection bias) | Unclear risk | Described as "randomly allocated". |
| Incomplete outcome data (attrition bias) | Low risk | 28% attrition (381/1013). 72/1013 (C = 35, I = 37) were excluded as they were over 20 weeks' gestation, had a twin pregnancy or were transferred to the chemical dependency clinic. 209/1013 (C = 109, I = 100) excluded due to transfer to another hospital, miscarriage, termination of pregnancy and withdrawal from the study. The numbers of those who withdrew from the study were not reported separately in this group, therefore all were re‐included as continuing smokers in this review (but were not included in mean outcome data). |
| Selective reporting (reporting bias) | Low risk | A detailed list of birth outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Urinary cotinine levels measured at baseline and in late pregnancy (< 115/ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Educational intervention delivered by clinic midwife. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Process evaluation showed 71% women in the intervention group received the full intervention. |
| Equal baseline characteristics in study arms | Low risk | There were no statistically significant differences between women allocated to the intervention and the control groups in terms of socio‐demographic variables and smoking patterns. |
| Contamination of control group | Low risk | Intervention provided by a research midwife, not UC provider. |
| Methods | 3‐armed randomised controlled trial aimed to evaluate the feasibility, cost and effectiveness of a telephone counselling intervention to support women to stop smoking in pregnancy. Study conducted at 22 urban prenatal care clinics in Rhode Island (Connecticut) and Massachusetts (USA). Study period not reported. | |
| Participants | Inclusion criteria: Pregnant women who had smoked at least 1 puff of a cigarette within the past 30 days, no more than 26 weeks pregnant, had access to a telephone where she could be reached, and speak English or Spanish. Exclusion criteria: Not further specified. Recruitment: 8526 pregnant women were assessed at their first or second visit. 1065/1582 eligible women (67%) agreed to participate and were randomly assigned to 3 conditions (C (self‐help materials) = 378; I1 (Self‐help materials + quit and win contest) = 329; I2 (self‐help materials + quit and win contest + MI counselling calls = 358). Baseline characteristics: Stratified by participation in calls: Mean cigarettes per day at baseline: 7.9 (6.3) to 8.7 (5.8). Baseline cotinine: 869 to 1239 ng/mL. Majority white, 40% <= 11 years education. Progress + coding: Low SES as 80% Medicaid recipients. | |
| Interventions | A: Control: Participants received self‐help materials, which included a quit kit (A Smoker’s Guide to Quit Smoking) and a video (Commit to Quit), which had been shown to be effective in significantly reducing exposure or assisting pregnant women to quit smoking (SCRIPT trials). B: Intervention 1: Received the quit kit and were enrolled in a ‘‘Quit and Win’’ (Q&W) monetary incentive lottery program. Eligibility for the prize (US$100) was restricted to smokers who reported abstinence for at least 30 days and had their report confirmed by urinary cotinine. This study ID compares the control group and Intervention 1 (arm b). Main intervention strategy: Incentives (single intervention) compared to a less intensive intervention. Intensity: Frequency (C = 1, I = 1), Duration (C = 1, I = 1). Intervention provided by dedicated project staff: Efficacy study. | |
| Outcomes | Self‐reported smoking cessation biochemically validated with urinary cotinine (< 80 ng/mL) at 32 weeks' gestation (late pregnancy)*, 6 weeks and 6 months postpartum (outcomes not reported). Cost‐effectiveness analysis. Outcome data from conference abstract with all 3 arms and 89% valid cotinine assessments used in this analysis, as outcome data for arms A and B in main report are unclear. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Not reported. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | Attrition: C = 101/378 (27%), I = 118/358 (33%) by 6 months postpartum (reasons not reported). All randomised women included in analysis. |
| Selective reporting (reporting bias) | Unclear risk | Smoking cessation at 6 weeks and 6 months postpartum not reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Biochemical validation of self‐reported smoking status using urinary cotinine (< 80 ng/mL). Conference report states only 219/245 women had a valid cotinine assessment, and 17.2% self‐reported smokers required reclassification. Pg 1045 states "Samples were obtained from 114 women during the first prenatal visit, from 113 during the third trimester, and 23 during the 6 month postpartum visit. We were unable to contact the remainder of the women, and therefore did not have samples to confirm their self‐reported smoking status". |
| Blinding of participants and personnel (performance bias) | Unclear risk | Not feasible for participants and personnel to be blinded to educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Process evaluation showed researchers were unable to reach 14%, 86% received 1 call, 60% 2 calls and 46% 3 calls. |
| Equal baseline characteristics in study arms | Low risk | The absence of significant differences for multiple salient predictors and other weaker predictors of smoking behaviour change strongly suggested that the call groups were comparable at baseline. |
| Contamination of control group | Low risk | Specific counsellors providing intervention so low risk of contamination. |
| Methods | 3‐armed randomised controlled trial aimed to evaluate the feasibility, cost and effectiveness of a telephone counselling intervention to support women to stop smoking in pregnancy. Study conducted at 22 urban prenatal care clinics in Rhode Island (Connecticut) and Massachusetts (USA). Study period not reported. | |
| Participants | Inclusion criteria: Pregnant women who had smoked at least 1 puff of a cigarette within the past 30 days, no more than 26 weeks pregnant, had access to a telephone where she could be reached, and speak English or Spanish. Exclusion criteria: Not further specified. Recruitment: 8526 pregnant women were assessed at their first or second visit. 1065/1582 eligible women (67%) agreed to participate and were randomly assigned to 3 conditions (C (self‐help materials) =378; I1 (Self‐help materials + quit and win contest) = 329; I2 (self‐help materials + quit and win contest + MI counselling calls = 358). Baseline characteristics: Stratified by participation in calls: Mean cigarettes per day at baseline: 7.9 (6.3) to 8.7 (5.8). Baseline cotinine: 869 to 1239 ng/mL. Majority white, 40% <= 11 years education. Progress + coding: Low SES as 80% Medicaid recipients. | |
| Interventions | A: Control: Participants received self‐help materials, which included a quit kit (A Smoker’s Guide to Quit Smoking) and a video (Commit to Quit), which had been shown to be effective in significantly reducing exposure or assisting pregnant women to quit smoking (SCRIPT trials). B: Intervention 1: Received the quit kit and were enrolled in a ‘‘Quit and Win’’ (Q&W) monetary incentive lottery program. Eligibility for the prize (US$100) was restricted to smokers who reported abstinence for at least 30 days and had their report confirmed by urinary cotinine. This study ID compares the control group (arm A) and Intervention 2 (arm C). Main intervention strategy: Counselling (multiple intervention) compared to a less intensive intervention. Intensity: Frequency (C = 1, I = 4), Duration (C = 1, I = 3). Intervention provided by dedicated project staff: Efficacy study. | |
| Outcomes | Self‐reported smoking cessation biochemically validated with urinary cotinine (< 80 ng/mL) at 32 weeks' gestation (late pregnancy)*, 6 weeks and 6 months postpartum (outcomes not reported). Cost‐effectiveness analysis. Outcome data from conference abstract with all 3 arms and 89% valid cotinine assessments used in this analysis, as outcome data for arms A and B in main report are unclear. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Not reported. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | Attrition: C = 101/378 (27%), I = 118/358 (33%) by 6 months postpartum (reasons not reported). All randomised women included in analysis. |
| Selective reporting (reporting bias) | High risk | Smoking cessation at 6 weeks and 6 months postpartum not reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Biochemical validation of self‐reported smoking status using urinary cotinine (< 80 ng/mL). Conference report states only 219/245 self‐reported quitters had biochemically confirmed smoking status, and 17.2% required reclassification. Pg 1045 states "Samples were obtained from 114 women during the first prenatal visit, from 113 during the third trimester, and 23 during the 6 month postpartum visit. We were unable to contact the remainder of the women, and therefore did not have samples to confirm their self‐reported smoking status". |
| Blinding of participants and personnel (performance bias) | Unclear risk | Not feasible for participants and personnel to be blinded to educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Process evaluation showed researchers were unable to reach 14%, 86% received 1 call, 60% 2 calls and 46% 3 calls. |
| Equal baseline characteristics in study arms | Low risk | The absence of significant differences for multiple salient predictors and other weaker predictors of smoking behaviour change strongly suggested that the call groups were comparable at baseline. |
| Contamination of control group | Low risk | Specific counsellors providing intervention so low risk of contamination. |
| Methods | Randomised controlled pilot study of a targeted intervention to support pregnant Alaskan Native women to stop smoking in pregnancy. Study conducted in the Y‐K Delta region in Western Alaska (USA), with recruitment from 2007 to 2008. | |
| Participants | Inclusion criteria: Pregnant Alaskan women ≥ 18 years, ≤ 24 weeks' gestation, self‐reported smoking or Iqmik/ST use in the last 7 days, planning to quit in the next 30 days, access to a telephone and VCR/DVD player, and willing to participate in all study procedures. Exclusion criteria: Planning an abortion, current (past 3 months) participation in pharmacological or behavioural tobacco treatment, and another woman from her household had enrolled. Recruitment: 293 women expressed an interest in the study and were referred to study co‐ordinator. 81 did not attend screening appointment, 114 reported not smoking and 4 were ineligible. 35/94 (37%) of the remaining eligible women agreed to participate and were randomised (C = 18, I = 17). Baseline smoking characteristics: Current tobacco use (in past 7 days): Iqmik C = 44% (8), I = 47% (8); Commercial chew C = 22% (4), I = 18% (3); Cigarette smoking C = 33% (6), I = 35% (6). Spouse/partner uses tobacco: C = 78% (14), I = 54% (7). Smoking ban in the home C =89% (16), I = 88% (14). Chewing ban in the home C = 12% (2), I = 19% (3). Baseline characteristics not reported. Progress + coding: Low SES, ethnic minority population. | |
| Interventions | Control: Participants in the control arm received an intervention consistent with the 5‐component treatment (5A’s) recommended for pregnant smokers by the Clinical Practice Guideline: Ask, Advise, Assess, Assist, and Arrange. At the first visit, participants in this condition received a brief (5‐min) face‐to‐face intervention based on the 5A’s and 4 pregnancy and culturally specific brochures. The counsellor encouraged and assisted the participant to set a quit date. Participants requesting NRT or another medication from the counsellor were referred to the YKDRH clinical cessation program and enrolment in this program was tracked as part of this study. Intervention: At the first visit women in the intervention group received: (i) a self‐help guide adapted from the SCRIPT trials (Windsor 1999) and from culturally appropriate brochures developed and used by the YKDRH clinical cessation program. (ii) 15‐25 mins of face‐to‐face counselling based on the 5A's. (iii) a video which was produced that included stories of Alaska Native women who stopped using tobacco during pregnancy. Focus groups suggested that story‐telling was a potentially acceptable intervention component. The counsellor then discussed the video with the woman. (iv) A further 4 x 10‐ to 15‐min proactive interactive sessions were provided by telephone, based on a counsellor manual which was developed based on completed evaluation research, at Weeks 1, 2, 4, and 6. These sessions provided opportunities for the counsellor to teach additional cessation skills and reinforce self‐efficacy. The woman was encouraged to set a quit date at each contact, if she had not quit. Main intervention strategies: Counselling (multiple intervention) compared to a less intensive intervention. Intensity: Frequency (C = 2, I = 6), Duration (C = 2, I = 3). Intervention provided by dedicated study staff: Efficacy study. | |
| Outcomes | Biochemically validated tobacco use in (salivary cotinine < 20 ng/mL) 60 days post randomisation (late pregnancy*). Acceptability to women. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | 35 participants were stratified by primary type of tobacco used (Iqmik, commercial ST, or cigarettes) and randomly assigned. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition: C = 1/18 (6%), I = 5/17 (29%). 1 miscarriage in each study arm excluded from this analysis. All other dropouts counted as continuing smokers. |
| Selective reporting (reporting bias) | Low risk | All primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Self‐reported tobacco use status biochemically validated using salivary cotinine (< 20 ng/mL). Some women were using NRT. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel to counselling intervention. |
| Blinding of outcome assessment (detection bias) | High risk | Not reported. |
| Incomplete implementation | Low risk | Process evaluation showed good treatment compliance and acceptability of intervention. |
| Equal baseline characteristics in study arms | High risk | Level of education and spouse/partner smoking unequal. |
| Contamination of control group | High risk | Assessments and interventions provided by the same individual in each community. |
| Methods | Cluster‐randomised controlled trial of implementation of the "Quit Together" program which aims to support women to stop smoking and prevent relapse in pregnancy. Study conducted WIC clinics in Massachusetts (USA) of implementation, with data collection from May 1997 to November 2000. | |
| Participants | Unit of randomisation was 6 community health centres with on‐site WIC programs, prenatal services and paediatric services, and patients of diverse race and ethnicity. 1 control site was dropped due to low recruitment. Inclusion criteria: Pregnant women, English or Spanish speaking, less than 32 weeks' gestation, current smoker or spontaneous quitter, planning to remain in area for 6 months after delivery. Exclusion criteria: Not further specified. Recruitment: 7853 women screened. 609/693 (88%) eligible smokers and ex‐smokers consented, completed baseline interviews and were randomised (C = 300, I = 309). Baseline characteristics: Current smokers (C =72.3%, I = 70.2%), spontaneous quitters (C = 27.7%, I = 29.8%). Mean cigarettes per day before pregnancy: C = 18.43, I = 14.89. Mean age 26 years. White (C = 78.6%, I = 22.8%), Black (C = 1.8%, I = 39%), Hispanic (C = 4.7%, I = 27.6%). Unmarried: C = 60.8%, I = 68.8%. Medicaid C = 63.1%, I = 65.5%. < High school C = 62.2%, I = 46.7%. Progress + coding: Low SES as high proportion of WIC recipients. | |
| Interventions | Control: UC condition, in which no training or intervention occurred. Intervention: The dissemination intervention consisted of: (i) provider training based on national clinical practice guidelines, (ii) an office practice management system for routine screening and follow‐up reminders, and (iii) establishment of program boards. The intervention to women was based on MI and the "4A's" from the 'SCRIPT trial' conducted by Windsor 2000b. Main intervention strategy: Counselling (single intervention) and intensive dissemination compared to UC. Intensity: Frequency (C = 0, I = 2), Duration (C = 0, I = 1). UC intensity: F = 0, D = 0. Intervention provided by existing staff: Effectiveness study. | |
| Outcomes | Biochemically validated smoking cessation and relapse prevention at 1 month postpartum combined (late pregnancy*), and 3 (0‐5*) and 6 (6‐11*) months postpartum. 6‐month figures not reported in text but estimated from Figure 3 to be I = 11%, C = 4%. Mean cigarettes/day* estimated from figure 4. Associated references describe detailed organisational change and implementation processes for the clinic setting (Zapka 2004), subanalysis of a range of outcomes by socio‐economic status; and clinical knowledge of nicotine dependence (Bonollo 2002). | |
| Notes | No estimates of clustering effect reported, so sensitivity analysis conducted and intracluster correlation of 0.10 used to adjust data for inclusion in outcome tables. SDs for mean cigarettes per day were not reported, therefore we calculated a mean SD from 14 studies with available mean cigarette SDs (6.5) to include in this review, as recommended by the cochrane handbook | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | No information provided. |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | High risk | 34/609 (6%) had a miscarriage and 12/609 (2%) transferred to another health service. 13 women excluded for other reasons (unexplained), but they are not reported by intervention group to be re‐included and the figures reported in the flow chart are combined with dropouts for other reasons. Also high loss to follow‐up. 550/609 women included in this analysis. |
| Selective reporting (reporting bias) | Unclear risk | Trial part of a nutritional program, but only smoking outcomes in this report. |
| Other bias | Unclear risk | One control site dropped due to low recruitment. Otherwise recruitment to study arms appears balanced. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | A woman was considered to be a smoker if she reported smoking in 30 days prior to 1 month postpartum interview. Salivary cotinine was analysed for women reporting abstinence in 7 days prior to the interview (<= 20 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Sites aware of allocation status. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Process evaluation not reported. |
| Equal baseline characteristics in study arms | Unclear risk | While no differences between SI and UC were statistically significant, some were large (e.g. race/ethnicity, education). This reflects the variability in size and race/ethnicity distributions among CHCs, the unit of randomisation. |
| Contamination of control group | Low risk | Cluster design to avoid contamination. |
| Methods | 3‐armed randomised controlled trial of self‐help materials and counselling to support women to stop smoking and prevent relapse during pregnancy and postpartum. Study conducted at a large Boston HMO (USA), with recruitment from March 1986 to September 1988. | |
| Participants | Inclusion criteria: English‐speaking literate women enrolling in prenatal care; who reported themselves as currently occasional or regular smokers or who had quit smoking in the previous 3 months. Exclusion criteria: < 18 years of age; > 24 weeks' gestation. Recruitment: 1442 women screened during early pregnancy class. 317 current smokers and recent quitters were identified. Participants from 3 centres were randomised to control and first intervention (I1) arms, and participants from the third arm (Intervention 2) were not randomly allocated and are not included in analysis in this review. 93/317 attrition, leaving 224 included (C = 78, I1 = 71, I2 (not randomised) = 75). Baseline characteristics: Baseline smokers: 142 (C = 47, I1 = 43, I2 = 52) and baseline spontaneous quitters: 104 (C = 36, I1 = 34, I2 = 34) analysed at 6 months gestation. Majority 17‐28 years, No participants less than high school, less than $US 20000/yr (C = 18.7%, I1 = 20%, I2 = 32.3%). Over 80% married and majority white. Progress + coding: None. | |
| Interventions | A: Control: Routine obstetric care, including a mailed list of community‐based smoking cessation resources other pregnancy‐related health education materials. Brief repeated counselling by obstetricians and midwives for both groups as part of routine care. C: Intervention 2: As for I1 plus training for obstetrician and nurse practitioner to provide training, and support letters from physician. Main intervention strategy: Health education (single intervention) compared to UC. Intervention 1 and control only compared in this review as arm C was not randomised. Intensity: Frequency (C = 0, I = 2), Duration (C = 0, I = 1). Intervention provided by dedicated project staff: Efficacy study. | |
| Outcomes | Smoking cessation for smokers and spontaneous quitters at 6 months gestation (late pregnancy* and 8 weeks postpartum (0‐5 months*). Description of costs. | |
| Notes | Substantial misclassification of non‐smoking self‐report at 6 months gestation 24% controls 21% intervention (and 30% in clinic where the intervention was more intensive). | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Table of random numbers. Allocation to intervention arm 2 was not randomised but offered to all eligible enrollees at 1 clinic: therefore data from this intervention arm are not included in the review. |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | High risk | 93/317 (29%) were excluded from analyses due to miscarriage, therapeutic abortion, moving, or left the Harvard Health Plan, leaving 217 included. However, 246 (C = 83, I1 = 77, I2 = 86) 'baseline smokers and spontaneous quitters' included in analysis at 6 months gestation and 219 included in 8 weeks postpartum. It is not clear which randomised women are included in analysis. |
| Selective reporting (reporting bias) | Unclear risk | None apparent but results were not simple to interpret. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation in 50% women. Those refusing urine test were coded as smoking. |
| Blinding of participants and personnel (performance bias) | Unclear risk | State that caregivers were blinded as materials to the intervention group were mailed. Not feasible to blind women. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | All women received materials for intervention 1 used in this review. Some implementation problems noted with the counselling arm (I2), but that was not included in this review. |
| Equal baseline characteristics in study arms | High risk | Differences in educational attainment. |
| Contamination of control group | Low risk | Unlikely with mail out of materials. |
| Methods | Cluster‐randomised trial of intervention to support women to stop smoking and prevent relapse in pregnancy and postpartum. Study conducted in the Lodz district, Poland, with data collection from December 2000 to December 2001. | |
| Participants | Unit of randomisation was maternity units, selected from 33 in district and stratified by size. Control = 1 small, 2 medium, 2 big; Intervention = 2 small, 4 medium, 4 big (as higher refusal expected in intervention arms. Inclusion criteria: Current smokers or women who quit 1 month before the visit. Exclusion criteria: Not further specified. Recruitment: 15/33 maternity units were allocated to intervention (10) or control (5) groups. All pregnant women screened. 194/194 (100%) eligible women in control group and 216/275 (78.5%) eligible women in the intervention group agreed to participate. Baseline characteristics: Current smokers: C = 156, I = 158. Spontaneous quitters: C = 38, I = 58. Cigarettes per day: < 5 (C = 8.8%, I = 10.3%), 5‐50 (C = 54.7%, I = 46%), > 10 (C = 36.5%, I = 43.7%). Fagerstrom score 0‐6 (C = 98.9%, I = 92.3%). Mean age: C = 25.9, I = 25.5; < 12 years education: C = 76.2%, I = 74.3%; Unmarried: C = 39.2%, I = 52.5%. Progress + coding: Low SES population as described by author. | |
| Interventions | Control: Received standard written information about health risks of smoking. Intervention: Received 4‐9 midwife home visits, based on a booklet translated from English (Ottawa) to Polish and adapted to Polish conditions: "How to talk about smoking with high risk pregnant smokers". Main intervention strategy: Counselling (single intervention) compared to UC. Intensity: Frequency (C = 0, I = 6), Duration (C = 0, I = 4). UC intensity: F = 1, D = 1. Intervention provided by midwives, which appear to be existing staff, though this is not explicitly reported: coded as effectiveness study. | |
| Outcomes | Self‐reported smoking cessation 'shortly after delivery at home' (0‐5 months postpartum*). Relapse prevention rates* in text (p274). Mean birthweight* calculated by combined smokers and quitters in Table 6. An associated reference (Polanska 2005) reports relapse after 12 months* (12‐17 months postpartum). All randomised from women from original study included as denominator and those not included in the follow‐up analysis assumed to have relapsed in this review. Spontaneous quitters and smokers combined from Table 2 to calculate self‐reported abstinence at 12 months. | |
| Notes | No estimates of clustering effect reported, so sensitivity analysis conducted and intracluster correlation of 0.10 used to adjust data for inclusion in outcome tables. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Notes random allocation, but no description of how this occurred. Only 15/33 eligible clinics allocated. |
| Allocation concealment (selection bias) | Unclear risk | Not specified. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition: Miscarriages: Smokers: I = 9/158 and C = 12/156. Spontaneous quitters: I = 2/58 and C = 1/38. Not included in analysis. Those lost to follow‐up: Smokers: (C = 6, I = 6) and Spontaneous quitters (C = 0, I = 2) are included in analysis of smoking outcomes. |
| Selective reporting (reporting bias) | Unclear risk | Birthweight and relapse prevention outcomes difficult to interpret and unable to be included. |
| Other bias | Unclear risk | Twice as many sites were allocated to the intervention arms as the control arms as it was assumed more women would refuse to participate in intervention activities. However recruitment to study arms was equal. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Self‐reported smoking status only. |
| Blinding of participants and personnel (performance bias) | High risk | Participants and personnel not blinded to this educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Number of visits received not reported. |
| Equal baseline characteristics in study arms | High risk | Intervention group more likely to be married, have fewer children, and have a higher smoking addiction. |
| Contamination of control group | Low risk | Cluster‐design to minimise risk of contamination. |
| Methods | This 2‐armed randomised controlled trial aimed to determine the acceptability of a SMS text based Scheduled gradual reduction (SGR) intervention plus support messages to promote cessation during pregnancy. This study was conducted in the USA with women recruited from 4 clinics, including a county health department that provides care for uninsured and underinsured patients as well as a U.S. Army medical center. | |
| Participants | Inclusion criteria: > 18 years of age, English‐speaking, have smoked at least 100 cigarettes in their lifetime, smoked 5 or more cigarettes per day in the prior 7 days, are willing to try quit smoking, are between 10 and 30 weeks pregnant, and have a cell phone with unlimited texting. Exclusion criteria: Women were excluded if they could not properly provide consent. Recruitment: 31/64 = 48% participation rate (C = 15 I = 16) Study staff obtained written consent from women. Baseline characteristics: Mean Age (C = 27 I = 29) Mean number of cigarettes per day (C = 10 I = 10) Partner smokes (C = 87% I = 56%) Further than high school (C = 53% I = 38%). Progress + coding: None. | |
| Interventions | Control: SMS support messages, women were asked to choose a quit date within the next 2‐3 weeks and then texted them that quit date. Staff explained that women would receive up to 5 messages per day for 5 weeks. Each week there was a new theme for a subset of messages, such as reasons for quitting, getting ready for quit date, partner smoking and handling slips. Intervention: Support messages plus a scheduled gradual reduction (SGR) Staff told women randomised to support messages plus SGR that they would receive support messages for 5 weeks as described in Support Messages Alone section. Instead of setting a quit date within 2–3 weeks, they received “alert messages”that were designed to help them gradually cut down to zero cigarettes by the end of the 4th week. Study staff explained that the purpose of the SGR program was to break the connection between cues and smoking. Staff explained that it works when women follow the schedule closely, smoking only when they receive alerts. Main Intervention strategy: Health Education (single) v alternative Intervention Intensity: Frequency (C = 6, I = 6) Duration (C = 4, I = 4). Technological intervention: unclear if efficacy or effectiveness. | |
| Outcomes | Biochemically validated 7‐day point prevalence of smoking cessation at end of pregnancy*. Many outcomes were based around the feasibility, acceptability and efficacy of the intervention and study itself. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Study staff randomised women, stratified by number of cigarettes smoked and partner smoking status. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | Those who were lost to follow‐up were counted as smokers. |
| Selective reporting (reporting bias) | Low risk | As this is a pilot study, efficacy, validity and feasibility were all reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking was biochemically validated, saliva samples were analysed for the presence of cotinine using radioimmunoassay. A cut point of 10 ng/mL for saliva cotinine with pregnant women was used to discriminate abstainers and smokers. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Participants and personnel likely to have been aware of group allocation, although not explicitly stated. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Unclear as to whether the research staff were blinded to the outcome assessment. |
| Incomplete implementation | Low risk | Of the 31 women enrolled, 86% of women in both arms reported reading “all or most” of the support messages. Women in the SGR arm responded to 68% of alert texts within 60 min. |
| Equal baseline characteristics in study arms | Unclear risk | Women in the control arm were more likely to be partnered with a smoker. Women in the intervention arm were heavier smokers, were less likely to have reduced their smoking during the pregnancy, and were less likely to have attempted to quit. |
| Contamination of control group | Low risk | Intervention was provided directly to participants via their mobile phone, so low risk of contamination. |
| Methods | This 2‐armed randomised controlled trial aimed to assess the impact of 20 mins of exercise on cravings amongst pregnant smokers who were recruited from London, Ontario, Canada and St. George's Hospital, South West London, England. | |
| Participants | Inclusion criteria: Pregnant women between 20 and 40 years of age, in their second trimester of pregnancy (13–24 weeks), smoking more than 5 cigarettes per day and at least 10 cigarettes per day prior to gravidity, were not receiving psychiatric treatment, did not present contraindications to exercise, and did not meet the physical activity guidelines for pregnancy (i.e. exercising less than 3 times per week for 30 mins at a moderate intensity; Participants were also screened with the Physical Activity Readiness Medical Examination for pregnancy for contraindications to exercise. Exclusion criteria: Not stated. Recruitment: 30 eligible women (C = 16 I = 14) There were no significant differences between the 2 samples in the 2 locations. Baseline characteristics: Mean Age‐ 25.7 years, Fagerstrom Test for cigarette dependence ‐ 3.3, Progress + coding: None. | |
| Interventions | Control: Passive control condition required participants to watch a 27‐min gardening show to reduce cravings Intervention: The exercise condition entailed a single bout of treadmill walking at a mild‐to‐moderate intensity (25% to 55% of heart‐rate reserve) for 20 mins, which commenced upon reaching the lower limit of the heart‐rate prescription. Approximately 2 mins and 5 mins were allocated for warm‐up and cool‐down, respectively. Main Intervention strategy: Single smoking cessation intervention: exercise vs alternative Intervention Intensity: Frequency (C = 1 I = 1) Duration (C = 2 I = 2). Intervention provided by study staff: efficacy study | |
| Outcomes | No smoking cessation outcomes reported. Primary outcomes were cigarette cravings and tobacco withdrawal symptoms. Cigarette cravings were assessed using a 7 point scale (1=not at all, 4=somewhat, 7=extremely) Tobacco withdrawal symptoms (irritability, tension, restlessness, difficulty concentrating and stress) were tested using the Mood and Physical Symptoms Scale. See Table 2 for summary of results. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Randomisation was reported to have been carried out with a computer‐generated scheme. |
| Allocation concealment (selection bias) | Unclear risk | Group allocation was concealed from participants but not researchers, as participants were informed of the aims of the study. |
| Incomplete outcome data (attrition bias) | Unclear risk | No reports of missing data or participants lost to follow‐up, so no detail regarding incomplete data or attrition rates in study arms. |
| Selective reporting (reporting bias) | Unclear risk | No smoking outcomes were reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking was biochemically validated and abstinence was confirmed by a reduction in expired CO levels (< 10 ppm), but is not reported. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Group allocation was concealed from participants, but not researchers. |
| Blinding of outcome assessment (detection bias) | Unclear risk | No detail regarding who undertook the outcome assessment and whether they were blind to allocation of participant. |
| Incomplete implementation | Unclear risk | No details of implementation. |
| Equal baseline characteristics in study arms | High risk | Marital status, number of previous quit attempts and hours abstained from smoking was different from control and intervention groups (37.5% married in intervention and 0% in control). |
| Contamination of control group | Low risk | Intervention was exercise so unlikely contamination of control group. |
| Methods | 3‐armed randomised controlled trial of 2 brief interventions to support women to stop smoking in pregnancy. Study conducted in an inner urban setting, Toledo, Ohio (USA), with recruitment from December 1987 to March 1989. | |
| Participants | Inclusion criteria: Not specified. Exclusion criteria: > 28 weeks' gestation. Recruitment: All 1,164 patients screened, 486 current smokers (42%). 293 refused or were ineligible (40% participation). 193 smokers randomised to study (C = 71, I1 = 52, I2 = 70). Baseline characteristics: Baseline smoking not reported. Mean age = 22.6 (5.6), ranging from 15‐43 years. 58% single, 70% white, 87% had not graduated from high school. Author describes population as "Typically low income, single and poor". Progress + coding: Low SES. | |
| Interventions | A: Control: UC not specified or assessed but "usual for physicians to address this issue with participants at least 1 prenatal visit". C: Intervention 2: Tailored educational videotape 6.5 mins, potential fetal risks, benefits if mother quit + pamphlet on how to quit and opportunity to ask questions of the health educator. 1 month later they viewed a second 4‐min video and the health educator was available to answer questions. Main intervention strategy: Counselling (single intervention) compared to UC. The control and intervention 1 (arm b) are compared in this study ID. Intensity: Frequency (C = 0, I = 2), Duration (C = 0, I = 1). Intervention provided by dedicated project staff: Efficacy study. | |
| Outcomes | Biochemically validated smoking cessation 'two or three weeks prior to delivery' (late pregnancy*). Smoking reduction* and mean cigarettes/day*. | |
| Notes | Program was developed with input from a questionnaire (based on Health Belief Model) and open‐ended questions about the advantages and disadvantages of smoking when pregnant from local population. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Not reported. |
| Allocation concealment (selection bias) | High risk | Tossed die (allocation could therefore be changed). Method resulted in 3 unequal groups, so randomisation to only 2 groups for some of the study period, which was the control and intervention 2 (videotape) group, compared in this review. |
| Incomplete outcome data (attrition bias) | Low risk | Attrition 44% (C = 46, I1 = 13,I2 = 25). Reasons for attrition not reported. However all dropouts treated as continuing smokers in this review. |
| Selective reporting (reporting bias) | Low risk | Primary outcomes appear to be reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking cessation was biochemically validated using exhaled CO (<= 7 ppm cut‐off). |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel to counselling intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | 44% did not receive intervention. |
| Equal baseline characteristics in study arms | Unclear risk | Not reported. |
| Contamination of control group | Low risk | Specific educators providing intervention (pregnancy care providers not involved). |
| Methods | 3‐armed randomised controlled trial of 2 brief interventions to support women to stop smoking in pregnancy. Study conducted in an inner urban setting, Toledo, Ohio (USA), with recruitment from December 1987 to March 1989. | |
| Participants | Inclusion criteria: Not specified. Exclusion criteria: > 28 weeks' gestation. Recruitment: All 1,164 patients screened, 486 current smokers (42%). 293 refused or were ineligible (40% participation). 193 smokers randomised to study (C = 71, I1 = 52, I2 = 70). Baseline characteristics: Baseline smoking not reported. Mean age=22.6 (5.6), ranging from 15‐43 years. 58% single, 70% white, 87% had not graduated from high school. Author describes population as "Typically low income, single and poor". Progress + coding: Low SES. | |
| Interventions | A: Control: UC not specified or assessed but "usual for physicians to address this issue with participants at least 1 prenatal visit". C: Intervention 2: Tailored educational videotape 6.5 mins, potential fetal risks, benefits if mother quit + pamphlet on how to quit and opportunity to ask questions of the health educator. 1 month later they viewed a second 4‐min video and the health educator was available to answer questions. Main intervention strategy: Counselling (single intervention) compared to UC. The control and intervention 2 (video‐tape, arm c) are compared in this study ID. Intensity: Frequency (C = 0, I = 3), Duration (C = 0, I = 2). Intervention provided by dedicated project staff: Efficacy study. | |
| Outcomes | Biochemically validated smoking cessation 'two or three weeks prior to delivery' (late pregnancy*). Smoking reduction* and mean cigarettes/day*. | |
| Notes | Program was developed with input from a questionnaire (based on Health Belief Model) and open‐ended questions about the advantages and disadvantages of smoking when pregnant from local population. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Not reported. |
| Allocation concealment (selection bias) | High risk | Tossed die (allocation could therefore be changed). Method resulted in 3 unequal groups, so randomisation to only 2 groups for some of the study period, which was the control and intervention 2 (videotape) group, compared in this review. |
| Incomplete outcome data (attrition bias) | Low risk | Attrition 44% (C = 46, I1 = 13,I2 = 25). Reasons for attrition not reported. However all dropouts treated as continuing smokers in this review. |
| Selective reporting (reporting bias) | Low risk | Primary outcomes appear to be reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking cessation was biochemically validated using exhaled CO (<= 7 ppm cut‐off). |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel to counselling intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | 44% did not receive intervention. |
| Equal baseline characteristics in study arms | Unclear risk | Not reported. |
| Contamination of control group | Low risk | Specific educators providing intervention (pregnancy care providers not involved). |
| Methods | Randomised controlled trial of US feedback on health beliefs and behaviours to improve maternal health, including smoking. Study conducted in London, England (UK). Recruitment dates not specified. | |
| Participants | Inclusion criteria: Caucasian origin, aged between 18 and 32 years, married or within a stable relationship, attending King's College Hospital AN booking clinics. Exclusion criteria: Women with a previous history of miscarriage, extended infertility investigations, or meet criteria for risk of congenital malformations. Recruitment: Women 'briefly informed that the study involved a continuing evaluation of aspects of obstetric care and that they would be seen on occasions throughout the pregnancy'. 6 women refused. 194 women recruited (see associated reference (Reading 1982), and were randomised to 3 arms: control (delayed US) = 55;I1 (low feedback) = 62; and I2 (high feedback = 67). The control arm was added during the course of recruitment and is not included in this review. 129 women included, 65 (50%) smokers at baseline (I1 = 26/62, I 2= 39/67). Baseline characteristics: Smoking characteristics not reported. Selective inclusion criteria: Pregnant women at 10‐14 weeks' gestation; 18 to 32 years; 85% had planned pregnancy, at low risk of complications; 86% nulliparous. Progress + coding: None. | |
| Interventions | A: Control: Women were assessed in the clinic following a delay interval. B: Intervention 1 (low feedback): Routine US at 16 weeks' gestation in which women were unable to view the monitor screen, did not receive specific visual or verbal feedback, and they received a global evaluation of the form "all is well". Main intervention strategy: Maternal health intervention with smoking component: Feedback (single intervention) compared to UC. Intervention 1 (B:low feedback) compared to Intervention 2 (C:high feedback) in this review as no control group outcomes reported. Control group details only reported in associated reference, but no smoking outcomes available. Intensity: Frequency (C = 1, I = 1), Duration (C = 1, I = 1). Unclear whether dedicated project staff delivered the intervention or not. | |
| Outcomes | Self‐reported smoking cessation at 16 weeks' gestation (late pregnancy*), without biochemical validation. Self‐reported reduction in smoking*. | |
| Notes | Cites evidence for the reliability of self‐report. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as "assigned at random". |
| Allocation concealment (selection bias) | Unclear risk | No information. |
| Incomplete outcome data (attrition bias) | High risk | Attrition: 3/129 (2%) from low feedback group in smoking outcomes. But considerable amounts of missing data for some variables. Those lost to follow‐up not included in ITT analysis, and unclear whether they were smokers at baseline so not re‐included. |
| Selective reporting (reporting bias) | Unclear risk | Data collected not specified. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | No biochemical validation of quitting. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Intervention with verbal feedback, so not feasible to blind women. State that those providing care were not involved in the study. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | 3/62 low feedback group did not attend next visit at 16 weeks. |
| Equal baseline characteristics in study arms | Low risk | Data in Tables 1 and 2 seem similar. |
| Contamination of control group | High risk | Assuming same ultrasonographer providing intervention for control and intervention groups. |
| Methods | Randomised controlled trial of a telephone counselling intervention to support women to stop smoking and prevent relapse during pregnancy and postpartum. Study conducted in a network‐managed care organisation and a group of 65 community‐based prenatal care practices Massachusetts, New England (USA), with recruitment from September 2001 to July 2004. | |
| Participants | Inclusion criteria: Pregnant smokers (at least 1 cigarette in the past 7 days), at least 18 years of age, 26 weeks or less gestation, willing to consider altering smoking during pregnancy, reachable by telephone, English speaking and expected to live in New England for the next year. Exclusion criteria: Not further specified. Recruitment: Smokers initially identified on 'Obstetric Risk Assessment' form, yielded low recruitment so 65/140 obstetric or family practices agreed to refer patients and 35 sent in 1 or more referral forms. 1444 pregnant smokers were referred to the study and 665 assessed as eligible. 442/446 (66%) agreed to participate and were randomised (C = 222, I = 220). Baseline characteristics: Mean cigarettes per day before pregnancy: C = 20.8, I = 20.9; Current mean cigarettes per day: C = 10, I = 10.4; Partner smoking: C = 62%, I = 71%. Mean age: C = 28.1, I = 28.9; Mean years education: C = 13, I = 13.1; White: C = 87%, I = 88%; Private health insurance: C = 70%, I = 75%. Depression in last month: C = 1.3%, I = 1.3%. Progress + coding: None. | |
| Interventions | Control: In addition to UC, the control group were mailed a validated pregnancy‐tailored smoking cessation booklet, and their prenatal care providers were sent the ACOG smoking cessation practice guideline, with a reminder to address smoking at the participant's visits. The enrolment call concluded with a trained counsellor providing brief smoking counselling (less than 5 mins). Smokers who requested further assistance were referred to the Massachusetts telephone quit‐line. Intervention: The intervention group received as for the control group, plus a series of telephone calls accompanied by additional mailed written materials. Each participant had a dedicated counsellor who offered up to 90 mins of counselling during pregnancy and up to 15 mins over the 2 months postpartum. The trained counsellor tailored the call to the participant's needs, consistent with the 5‐step smoking cessation guideline, and drew on social learning theory and the transtheoretical model of change, the health belief model, and the principles of MI. Main intervention strategy: Counselling (multiple intervention) compared to a less intensive intervention. Intensity: Frequency (C = 2, I = 4), Duration (C = 1, I = 3). | |
| Outcomes | Biochemically validated 7‐day point prevalence abstinence at 28 weeks to term (late pregnancy*), and 3 (0‐5) months postpartum*. Also measured reduction in smoking (proportion > 50% reduction in cigarettes per day*), sustained abstinence at both time points, and number of quit attempts. Self‐efficacy and social support at baseline and follow‐up. Concerns about weight gain reported in an associated reference (Berg 2008). Women's satisfaction with the intervention. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer‐generated. |
| Allocation concealment (selection bias) | Low risk | Stated that recruiters were not aware of group allocation. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition: 21/442 (5%) were excluded from the analysis due to miscarriage (C = 10/220, I = 11/222). 113 women did not have final assessment due to refusal (22%), baby born before assessment or lost to follow‐up, but were included in the final analysis (ITT analysis) and in this review (C = 209, I = 212). Missing data (up to 30%) for outcomes measured in the postnatal period. |
| Selective reporting (reporting bias) | High risk | Not clear if all outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Salivary cotinine (<= 20 ng/mL cut‐off) confirmation in 66%, and those refusing to provide a sample were included as continuing smokers. |
| Blinding of participants and personnel (performance bias) | High risk | All providers and women sent smoking cessation practice guideline. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | Mean number of calls received was 5. |
| Equal baseline characteristics in study arms | High risk | Both groups were similar, though the intervention group had a significantly higher proportion of women who had made a quit attempt this pregnancy and had social support to quit from partner and significant differences in parity, gestation, and partner smoking |
| Contamination of control group | Low risk | Trained counsellors delivering intervention not UC givers. |
| Methods | This non‐blinded, randomised controlled, parallel‐group trial. The Family Nurse Partnership (FNP) aimed to improve maternal and child outcomes for teenage first‐time mothers and included a smoking cessation component, The study was conducted in community settings at 18 partnerships between local authorities and primary and secondary care organisation within England, UK and recruitment ran from June 16, 2009, and July 28, 2010. | |
| Participants | Inclusion criteria: To be eligible, women had to be nulliparous, aged 19 years or younger, living within the catchment area of a local FNP team, at less than 25 weeks’ gestation, and able to provide consent and speak English. Women expecting multiple births and those with a previous pregnancy ending in miscarriage, stillbirth, or termination were eligible. Exclusion criteria: Women planning to have their child adopted or to move outside of the FNP catchment area for longer than 3 months were not eligible. Recruitment: Women were identified and approached via local maternity services and recruited usually at their home by locally‐based researchers. 3251 women were screened, with 1645 women randomised to intervention or control. However it is unclear what proportion of these were smokers. Baseline characteristics: Characteristics of smokers participating is unclear as participants are smokers and non‐smokers. Progress + coding: Low SES as low rates of employment (20%) among both smokers and non‐smokers. | |
| Interventions | Control: UC, all participants (universally offered) received publicly funded health and social care, which included screening, education and immunisation and support from birth to child's second birthday Intervention: The FNP is a home visiting intervention that involves up to 64 structured home visits with a protocol to guide smoking cessation advice. Core specialist Main Intervention strategy: Maternal health intervention with smoking cessation component; social support (single) vs UC. Intensity: Frequency: (C = 0, I =6), Duration: (C = 0, I =4). However it is unclear what proportion of these visits included discussions on smoking cessation. | |
| Outcomes | Biochemically validated abstinence in late pregnancy (34‐36 weeks' gestation)*. Other outcomes not reported by smoking status, and other aspects of the intervention may have contributed to these outcomes and so they are not reported in this review. (Birthweight (child measure), emergency attendances and hospital admissions of child within 2 years of birth, and proportion of women with a second pregnancy within 2 years of first birth. Secondary outcomes include: Intention to breastfeed, Prenatal attachment, Injuries and ingestions, Breast feeding (initiation and duration), Language development, Education, Employment, Income/benefits, Home (tenure), Health status, Self‐efficacy, Social support and Paternal involvement). | |
| Notes | Difference in study arm denominator data between table 1 (I = 428 and C = 442) and S6.1 appendix (I = 439 and C = 431) but totals the same (870) baseline smokers, but we used data from S6.1 in this review. No response from authors to request for clarification. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Researchers will use a remote randomisation service (automated telephone or web) provided by Bristol Randomised Trials Collaboration (BRTC) to allocate the woman to the intervention or UC. |
| Allocation concealment (selection bias) | Low risk | Automated allocation. |
| Incomplete outcome data (attrition bias) | Low risk | All analyses were done by ITT without imputation, with outcome values compared between groups using mixed‐effects 3‐level regression models to adjust for site as a stratification variable and to allow for clustering by a family nurse in the intervention group. |
| Selective reporting (reporting bias) | Low risk | All outcomes reported. |
| Other bias | Unclear risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Biomarker calibrated self‐reported tobacco use by the mother at late pregnancy. When only baseline cotinine concentrations were available, women reporting not smoking at late pregnancy and who were classified as either accurate or over‐reporters of tobacco use (from comparing baseline self‐report and cotinine concentrations; appendix) were also categorised as non‐smokers. Urinary cotinine < 100 ng/mL considered non‐smokers. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel to counselling intervention. |
| Blinding of outcome assessment (detection bias) | Low risk | Mothers and field‐based researchers (even if also assessors) were not masked to group allocation, but assessors collecting data by computer‐assisted telephone interview were masked to allocation. |
| Incomplete implementation | Low risk | Process evaluation showed that > 99% received at least 1 visit, The average nurse‐reported duration of valid visits was 79 mins. Clients receive 80%/65%/60% or more of expected visits during pregnancy, infancy, toddlerhood phase respectively. |
| Equal baseline characteristics in study arms | Low risk | No significant differences noted. |
| Contamination of control group | Low risk | Main intervention component is home visits therefore low risk of contamination of the control group. |
| Methods | Randomised controlled trial of counselling to support women to stop smoking in pregnancy and postpartum. Study conducted at the University of Vermont, Burlington (USA), with recruitment from May 1984 to June 1987. | |
| Participants | Inclusion criteria: Pregnant women less than 25 weeks' gestation, smoking at least 1 cigarette a day. Exclusion criteria: Not further specified. Recruitment: Women receiving prenatal care from obstetricians and nurse‐midwives, or residents through Maternal, Infant & Child clinic for under‐insured or non‐insured women, were randomly assigned (23% Medicaid in study). 775/808 (96%) smokers invited agreed to participate. 175/775 women spontaneously quit before their first visit and were randomised into a separate study of relapse prevention (C = 86, I = 89) (Secker‐Walker 1995). 600 smokers randomised (C = 300, I = 300). Baseline characteristics: Mean cigarettes per day pre‐pregnancy C = 25.1, I = 24.4. Mean cigarettes per day at first prenatal visit: C = 12.4, I = 14.1. Mean age: 24 years; Less than high school: C = 30.7%, I = 28.2%; Medicaid recipient C = 23.2%, I = 25.3% (50% private insurance). Progress + coding: Low SES due to high rates of women who had not completed high school. | |
| Interventions | Control: 'Usual advice about smoking provided by obstetrician or midwife'. The relapse prevention component was individualised but carried out within a defined protocol. Counselling about preventing relapse and a booklet. Follow‐up at second AN clinic, 36 weeks and 6‐week check (where infant health and parental role modelling was discussed) Main intervention strategy: Counselling (multiple intervention) compared to UC. Intensity: Frequency (C = 0, I = 3), Duration (C = 0, I = 3). UC intensity: F = 1, D = 1. Intervention provided by dedicated project staff: Efficacy study. | |
| Outcomes | Smoking cessation at 36 weeks' gestation (75% biochemically validated with cotinine) (late pregnancy*), Long‐term quitting measured at 8‐15 months' pp (6‐11 months pp*), 16‐24 pp (18 months postpartum), and 25‐54 pp (self‐reported). Relapse prevention* reported in associated reference (Secker‐Walker 1995). Mean birthweight*, LBW*, other smoking‐related complications (PPROM, placental abruption and placenta praevia). Reduction in mean cotinine/creatinine ratio at 36 weeks' gestation. | |
| Notes | Sample size calculated for 10% increase (from 10% to 20%) in quitting. Recall of advice about smoking. Separate paper (Secker‐Walker 1992) evaluates training program for residents. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as "randomly assigned". |
| Allocation concealment (selection bias) | Unclear risk | Not stated. Unclear when randomisation took place. |
| Incomplete outcome data (attrition bias) | Unclear risk | Smokers: Attrition 39/600 (6.5%) due to miscarriage (27), fetal deaths (7), infant deaths (5), 48 transferred care (C = 24, I = 24), and were excluded from analysis, leaving C = 258, I = 255. Further losses were: 41 dropped out of study (C = 4, I = 37), and 59 were lost to follow‐up (C = 28, I = 31), but were re‐included in this review as continuing smokers, but are not included in mean birthweight and other birth outcomes analyses. Significant difference in pregnancy dropout rates for I (13% dropout rate) and C (1.4% dropout rate). Those lost to follow‐up smoked more. Voluntary dropouts treated as continuing smokers for some analyses. Spontaneous quitters: attrition 8/175 (5%) due to miscarriage (5), abortion (1), fetal demise (1), and infant death (1) and lost records (2) were excluded from analysis, leaving C = 80, I = 85. Further attrition: transferred care (15)‐not reported by study arm, dropped out of study (9), lost to follow‐up (8), re‐included in baseline as continuing smokers in this review. Differential withdrawal in I and C groups a concern; good information collected on dropouts being different. |
| Selective reporting (reporting bias) | Unclear risk | Data collected not specified. Only smoking outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Urinary cotinine/creatinine ratio levels measured at 36 weeks (< 80 ng/mg). |
| Blinding of participants and personnel (performance bias) | High risk | Educational intervention in AN clinics. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | All but 9 intervention women not lost to follow‐up received all 3 counselling sessions before 36 weeks, and 89% received the postpartum 1. |
| Equal baseline characteristics in study arms | High risk | Mostly similar but women in intervention group tended to smoke more cigarettes at time of their first visit. |
| Contamination of control group | Low risk | A separate health educator provided intervention. |
| Methods | Randomised controlled trial of a videotape to support women to stop smoking in pregnancy. Study conducted in the offices of 'University Associates in Obstyetrics and Gynecology', in Burlington, Vermont (USA), with recruitment from November 1992 to April 1993. | |
| Participants | Inclusion criteria: Pregnant women smoking 'an average of one or more cigarettes per day'. Exclusion criteria: Not further specified. Recruitment: Women recruited through University prenatal clinics where obstetricians and nurse‐midwives provide private prenatal care, and residents provide prenatal care for under‐insured women. 60/67 (89%) smokers who were invited agreed to participate and were randomly assigned (C = 30, I = 30). Baseline characteristics: Mean cigarettes per day before pregnancy = 22.6. Mean age: 23 years; 30% married; 33% had less than high school education; 98% white. Progress + coding: Low SES in this review as participants recruited from a state‐supported clinic for underinsured women. | |
| Interventions | Control: Advice from an obstetrician or nurse‐midwife (as per prompt sheet) and a booklet on quitting. The protocol for this advice has been described in Secker‐Walker 1992. Intervention: As for control plus a 29‐min videotape of 4 women going through the process of quitting during pregnancy; talking about feelings; coping with weight gain; getting support, which could be borrowed and taken home. Based on social learning theory. Main intervention strategy: Counselling (single intervention) compared to a less intensive intervention. Intensity: Frequency (C = 1, I = 2), Duration (C = 1, I = 2). Unclear if technological intervention provided by existing staff or dedicated project staff. | |
| Outcomes | Smoking cessation in late pregnancy* (36/40), biochemically validated with exhaled CO measurements. Process evaluation included perceptions of the videotape contents. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as "randomly assigned". |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | Unclear risk | 4/60 (7%) women, all in the intervention had a miscarriage and 7 (C = 2, I = 5) moved to another care‐provider, and were excluded from the analysis. 3 (C = 1, I = 2) lost to follow‐up but were re‐included in this review, leaving C = 28, I = 21. Loss to follow‐up not balanced, greater loss from the intervention group. |
| Selective reporting (reporting bias) | Low risk | Not apparent. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Exhaled CO (< 8 ppm) used to validate self‐reported smoking cessation. |
| Blinding of participants and personnel (performance bias) | High risk | Educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | 53% viewed the videotape. 17% had no VCR, and 10% reported having no time. |
| Equal baseline characteristics in study arms | High risk | Mean exhaled CO level was significantly lower in intervention group. |
| Contamination of control group | Low risk | Video tape unlikely to be provided to women in control group. |
| Methods | Randomised controlled trial of a counselling intervention to support women to stop smoking in pregnancy and prevent relapse postpartum. The study was conducted in offices of the 'University Associates in Obstetrics and Gynecology' in Vermont (USA), with recruitment from October 1988 to October 1992. | |
| Participants | Inclusion criteria: Woman who reported smoking 1 or more cigarettes per day at onset of pregnancy. Exclusion criteria: Not further specified. Mean age: 23 years, < high school (C = 41%, I = 48%), 27% married; Medicaid recipients (C = 73.1%, I = 71.9%); Adolescent clinic (C = 13.5%, I = 11.9%). Spontaneous quitters: Mean cigarettes per day before pregnancy (C = 14.1, I = 13.5). Other smokers in household (C = 64%, I = 70%). Mean age: C = 21.9, I = 20.9; < high school (C = 27%, I = 36%); 29% married; Medicaid recipients (C = 68.1%, I = 65.1%); adolescent clinic (C = 14.9%, I = 11.4%). Progress + coding: Low SES. | |
| Interventions | Control: Physician acknowledged women's smoking, gave a rationale for quitting, strong recommendation to quit and provided smoking cessation booklet designed for pregnant women. All participants received: baseline questionnaire, measurement of exhaled CO, and brief standardised health risk message from a research nurse about the effects of smoking on the fetus and pregnancy. Main intervention strategy: Counselling (multiple intervention) compared to less intensive intervention. Intensity: Frequency (C = 1, I = 5), Duration (C = 1, I = 3). Intervention provided by existing staff, with referral to a counsellor: Effectiveness study. | |
| Outcomes | Biochemically validated 7‐day point prevalence abstinence at 36 weeks' gestation (late pregnancy *) and 1 year postpartum*. Mean cigarettes per day at 36 weeks' gestation* and 12 months postpartum. Mean exhaled CO*. Mean birthweight*. LBW*. Relapse prevention at 36 weeks' gestation (late pregnancy*) and 12 months postpartum reported in associated reference (Secker‐Walker 1998b) Preterm births* are reported in attrition and are re‐included in both numerator and denominator for this outcome. | |
| Notes | Methods included a detailed process evaluation of participants' views and recall of provider advice. Sample size justification. Separate paper reports relationship between exhaled CO and birthweight (Secker‐Walker 1997b) | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as "randomly assigned". |
| Allocation concealment (selection bias) | Unclear risk | No details provided. |
| Incomplete outcome data (attrition bias) | Unclear risk | High attrition. More than 25% lost to follow‐up in pregnancy and more than 30% lost to longer‐term follow‐up. Smokers: 109/399 (27% attrition) 24 (6%) women with miscarriage (14), fetal demise (5) and infant deaths (5) were excluded from analysis and are not reported by group allocation. Report states 376 women remain included (instead of 375) (C = 191, I = 185). 68 women transferred care (C = 34, I = 34), 17 delivered before 36 weeks (C = 8, I = 9) and were not included in 36‐week analysis. 12 women withdrew from study (C = 5, I = 7) and 3 lost to follow‐up (C = 3), and were re‐included as continuing smokers in this review, but are not included in mean cigarettes per day or perinatal outcomes. Spontaneous quitters: 33/125 (26%) attrition. Women with miscarriage (5), abortion (1), infant death (1), pregnancy loss (1), moving to another clinic or moving (22; C = 13, I = 9), delivering before 36 weeks (I = 2). All excluded from analysis leaving C = 48, I = 44. |
| Selective reporting (reporting bias) | Unclear risk | Only smoking outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Self‐reported cessation with biochemical validation by exhaled CO (< 6 ppm) or urinary cotinine (< 500 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Intervention by clinic staff. Notes flagged. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | Methods included a detailed process evaluation of participants' views and recall of provider advice and suggests ‘to a large extent the intervention was implemented as planned’. |
| Equal baseline characteristics in study arms | Unclear risk | No significant differences except for larger proportion of women in intervention group had not made a quit attempt in the past. |
| Contamination of control group | Unclear risk | No women in cessation group received cessation counselling beyond the physician advice. Though the same physician provided advice so unclear if this was influenced by the intervention. |
| Methods | Randomised controlled trial of a multifaceted intervention to support women to stop smoking in pregnancy. Study conducted in a large university hospital obstetric clinic in Baltimore (USA) with enrolment over a 2.5‐year period (dates not specified). | |
| Participants | Inclusion criteria: Pregnant women who were smoking >= 10 cigarettes/day immediately prior to pregnancy, < 18 weeks' gestation. Exclusion criteria: Not further specified. Recruitment: Eligible women sought by a variety of methods but majority were attending 1 of 52 private obstetricians or a hospital AN clinic. Obstetric staff sought permission for study staff to contact women. 935 women recruited (participation rate unclear) (C = 472, I = 463). 157/935 had spontaneously quit (C = 17% or 80, I = 16% or 74, which only add up to 154). Smoking rates among spontaneous quitters not reported separately so all randomised women included in analyses. Baseline characteristics: Mean cigarettes per day pre‐pregnancy: C = 20.7, I = 20.9; mean cigarettes per day at randomisation: C = 11.7, I = 10.7. Mean age 24.9 years, Mean education 12.3 years, Black C = 41.3%, I = 40.3%. Progress + coding: None. | |
| Interventions | Control: UC, not further specified. Main intervention strategy: Counselling (tailored) compared to UC. Intensity: Frequency (C = 0, I = 6), Duration (C = 0, I = 6). UC intensity: F = 0, I = 0. Intervention provided by dedicated study staff: Efficacy study. | |
| Outcomes | Self‐reported smoking at 8 months gestation (late pregnancy*). Mean cigarettes per day* at 8 months gestation and mean thiocyanate*. Mean birthweight*, LBW*, very LBW*, perinatal deaths*, neonatal deaths*, stillbirths*. % Apgar scores < 7 at 1 min and 5 mins; length and head circumference. | |
| Notes | Change of criteria for enrolment after the first 185 as 35% of these had smoked < 10/day and 71% of that group had quit spontaneously with little relapse. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Not stated. |
| Allocation concealment (selection bias) | Unclear risk | No information. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition: 56/935 (6%), 35 miscarriages (C = 17/572, I = 18/463), 1 fetal death (C = 1), 20 stillbirths (C = 11, I = 9) excluded from analysis, leaving C = 443, I = 436. Women lost to follow‐up included as continuing smokers in this review. Missing data for mean outcomes not included. |
| Selective reporting (reporting bias) | High risk | Extensive range of outcomes reported. Outcomes not reported separately for spontaneous quitters. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Self‐reported smoking outcomes were not validated by salivary thiocyanate, despite it being collected. Mean thiocyanate for each group reported only. |
| Blinding of participants and personnel (performance bias) | High risk | Educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Group sessions in the intervention were not readily accepted. |
| Equal baseline characteristics in study arms | Low risk | Groups 'similar' at time of randomisation. |
| Contamination of control group | Low risk | Specific personnel employed to deliver intervention ‐ not usual carers. |
| Methods | Randomised controlled trial of telephone peer support to help women stop smoking in pregnancy. Study conducted in a large obstetric practice in Burlington, Vermont (USA), with recruitment from 1996 to 1997. | |
| Participants | Inclusion criteria: Women reporting smoking at least 1 cigarette in the past week at their first AN visit. Exclusion criteria: Not further specified. Recruitment: 151/186 (81%) women approached agreed to participate and were randomised (C = 74, I = 77). Baseline characteristics: Mean cigarettes/day before pregnancy: C = 20.2, I = 22.6; Mean cigarettes per day at first visit: C = 9.8, I = 10.5. Mean exhaled CO: C = 11.3, I = 11.3. Mean other smokers in household: C = 1.5, I = 1.3. Mean age C = 23.7, I = 23.1; Mean years education: C = 11.5, I = 11.7; White: C = 96%, I = 94.8%. Medicaid recipient: C = 74.6%, C = 77.5%. Progress + coding: Low SES. | |
| Interventions | Control: Received brief smoking cessation advice (including encouraging a quit date) from a midwife or obstetrician at each of the 3 prenatal visits and stage‐appropriate printed materials. Midwives and obstetricians were provided with a 45‐min training session and protocol prompt sheets were placed in charts at first prenatal visits. Intervention: Received the same as the control group, plus any women in the experimental visit who reported they possibly, probably or definitely intended to quit smoking were offered telephone peer support by the obstetrician/midwife. The telephone peer support was provided by a female ex‐smoker, who received 8 hours of training. The support person called the participant within several days of referral to provide support, encouragement and reinforcement of positive changes in smoking behaviour. Ongoing calls typically occurred on a weekly basis, but more frequently around a quit date. On average calls lasted 10 mins. Main intervention strategy: Social support (tailored intervention) compared to a less intensive intervention. Intensity: Frequency: (C = 3, I = 6), Duration (C = 1, I = 4). Unclear whether intervention provided by dedicated or existing staff. | |
| Outcomes | Biochemically validated 7‐day point prevalence abstinence at 28‐34/40 gestation (late pregnancy*). Proportion of self‐reported smoking reduction by more than 50%* was reported for a proportion (135 women) but unclear how many had dropped out of intervention and control groups. As report states 'no significant difference' in dropouts by intervention group (total n = 16) we have imputed 8 for each arm and calculated the number of reductions from a proportion of the remaining sample. Movement in stages of change also reported for this group. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | States participants were randomised into either experimental or control condition. |
| Allocation concealment (selection bias) | Unclear risk | No information. |
| Incomplete outcome data (attrition bias) | Low risk | 16/151 (11%) attrition at follow‐up. Unclear how many from each arm, so outcomes (> 50% reduction and SOC movement) reported as a proportion of those remaining were not able to be included. All randomised women were included in the primary outcome of smoking cessation, with those lost to follow‐up treated as continuing smokers. |
| Selective reporting (reporting bias) | Unclear risk | Only smoking outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Urinary cotinine assessment at 28‐34 weeks used to confirm smoking status (cut‐off < 80 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel to allocation. Medical charts flagged and referral for social support required by care providers. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Process evaluation showed 53% received the peer intervention. 9 (12%) had low intentions of quitting smoking during pregnancy and were never offered the peer support, 9 (12%) had no home telephone and were not referred, and 15 (19%) refused the offering, leaving 44 (57%) who were referred for peer support. Data from log sheets completed by the telephone support person revealed that 3 women referred were never reached; therefore, only 53% of the women in the experimental condition received the peer support intervention. |
| Equal baseline characteristics in study arms | Low risk | Baseline comparisons of women in the experimental and control conditions revealed no significant differences in demographics, pregnancy history, or smoking information. |
| Contamination of control group | Low risk | Unlikely telephone counselling would have been provided to control group in error. |
| Methods | Randomised controlled trial of intensive late pregnancy intervention to support 'resistant' smokers to stop smoking in pregnancy. Study conducted in 3 large multispecialty clinics in Houstan and Dallas metropolitan areas, Texas (USA). Enrolment over a 17‐month period, dates not specified. | |
| Participants | Inclusion criteria: Women were screened for eligibility into 2 concurrent studies: Pregnant women who smoked more than 5 cigarettes per week prior to pregnancy, fluent in English, over 18 years, less than 20 weeks' gestation at first prenatal visit. Women who continue to smoke at 28 weeks' gestation, after having counselling and 8 self‐help booklets earlier in pregnancy care, and had telephone access, were eligible for this study. Exclusion criteria: Women who had quit smoking at 28 weeks (continuous abstinence for 28 days), were enrolled in a large trial to prevent postpartum relapse (Project PANDA). Recruitment: 6956 (99%) women completed intake screening. 1255 current and recent smokers received brief intervention in early pregnancy as described by Ershoff 1989. 522/1255 (42%) had transferred care, had fetal demise or abortion, were over 34 weeks' gestation, or could not be reached. All 269/733 (37%) who reported continuing to smoke at 28 weeks and were randomised to this study, as data collection and implementation were adopted as routine procedures, and required no formal written consent (C = 135, I = 134). Baseline characteristics: > 61 cigarettes/week before pregnancy: I = 57.9%, C = 43%; Partner smoking: C = 62.5%, I = 69.6%. Mean age: C = 28.1, I = 28.6; Married: C = 71.1%, I = 65.7%, White: C = 76.3%, I = 81.3%. < high school: C = 11%, I = 9%. Progress + coding: None. | |
| Interventions | Control: All women smoking at intake (< 20 weeks), were provided with MI counselling (3‐5 mins) and a series of 8 motivational self‐help books (first given in person and 7 mailed weekly thereafter), based on "stage of change" program as described by Ershoff 1989. Intervention: The high‐intensity intervention group (and their partners) then received: (i) a 20‐ to 30‐min MI telephone counselling call (conducted by trained counsellors and nurse health educators), (ii) a personalised, stages of change based feedback letter, (iii) a final MI‐based telephone call conducted 4‐5 days after the feedback letter was sent. The MI counselling calls were adapted from the Motivational Enhancement Therapy developed for Project MATCH (Miller 1992). Main intervention strategy: Counselling (multiple intervention) compared to less intensive intervention. Intensity: Frequency: (C = 6, I = 6), Duration: (C = 1, I = 3). Intervention provided by dedicated project staff: efficacy study. | |
| Outcomes | Biochemically validated smoking cessation at 34 weeks' gestation (late pregnancy*). Self‐reported smoking cessation at 6 weeks, 3 months* and 6 months* postpartum. Movement in "stages of change". Breastfeeding rates and general health behaviours obtained but not reported. Discussion of provider views. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer‐generated random number list. |
| Allocation concealment (selection bias) | Unclear risk | No details provided. |
| Incomplete outcome data (attrition bias) | Unclear risk | 35% attrition for cotinine testing: 175/269 provided cotinine subsample (C = 82, I = 84). 39% attrition for 6 weeks postpartum follow‐up. All women lost to follow‐up for cotinine validated smoking status at 36/40 were included in this review as continuing smokers. Analysis includes all randomised women. |
| Selective reporting (reporting bias) | Unclear risk | Only smoking outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Urinary cotinine analysis (cut‐off 80 ng/mL) for a subset of the sample at 34 weeks' gestation, but women without cotinine validation were included as continuing smokers. Postpartum outcomes self‐reported. |
| Blinding of participants and personnel (performance bias) | High risk | Participants and personnel likely to have been aware of group allocation, though no formal consent requested. |
| Blinding of outcome assessment (detection bias) | Low risk | Described as "single blind" (cotinine analysis performed blind). |
| Incomplete implementation | High risk | Only 55% of the experimental group received the full intervention (32% were never able to be reached). Implementation analysis suggested an effect in women who received full implementation: 43% vs 34% control group. |
| Equal baseline characteristics in study arms | High risk | Group differences were found on number of cigarettes smoked per week at baseline, but no differences in demographic variables. |
| Contamination of control group | Low risk | Specific counsellors delivered the intervention. |
| Methods | Randomised controlled trial (pilot study) of MI intervention to support women to stop smoking in pregnancy. Study conducted in a university‐based, public obstetric/gynaecology clinic (USA). Exact location and recruitment dates not reported. | |
| Participants | Inclusion criteria: Pregnant women who reported smoking in the past 7 days who were at least 16 years of age, fluent in English, less than 28 weeks' gestation. Exclusion criteria: Not further specified. Recruitment: Women attending a university‐based, public obstetric/gynaecology clinic. Unclear how many women were approached or eligible, though author communication reports challenges with recruitment. 54 women randomised (C = 28, I = 21, from author communication). Baseline characteristics: Not reported but discussion describes women as 'socio‐economically disadvantaged pregnant smokers'. Progress + coding: Low SES. | |
| Interventions | Control: UC, which in this university‐based prenatal clinic included physicians or nurses acknowledging a pregnant woman’s reported smoking and recommending that she quit. Intervention: MI intervention over the course of 8 weeks: (i) 1 face‐to‐face MI session; (ii) 3 MI‐based telephone counselling calls; and (iii) 1 personalised feedback letter providing assessment results. MI incorporated specific counselling strategies, including personalised and objective feedback, to create a supportive, non‐confrontational environment through which clients can resolve ambivalence and initiate change. Main intervention strategy: Counselling (multiple intervention) compared to UC. Intensity: Frequency: (C = 0, I = 4), Duration (C = 0, I = 2). UC intensity F = 1, I = 1. 2 masters‐level counsellors delivered the intervention: Efficacy study. | |
| Outcomes | Biochemically validated smoking cessation at post‐treatment assessment (late pregnancy*). Stages of change, processes of change, self‐efficacy, decisional balance, and depression scores also reported. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | States women 'were randomized' into an intervention or UC condition. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Unclear risk | Outcomes reported as percentages. 5 women excluded from the analysis (as per author communication) for which there was no data (C = 2, I = 3), so abstinent percentages are based on C = 5/28 and I = 3/21. These women were included as continuing smokers in this review. |
| Selective reporting (reporting bias) | Unclear risk | Primary outcomes reported, author communication states low recruitment so focused on other outcomes in this pilot study. |
| Other bias | Unclear risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemically validated smoking cessation with salivary cotinine (cut‐off > 20 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel to counselling intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Not reported. |
| Equal baseline characteristics in study arms | Low risk | Not reported but author states " Initial comparisons of socio‐demographic and smoking history variables revealed no differences between the MI and UC groups" |
| Contamination of control group | Low risk | Unlikely as intervention delivered by specific counsellors. |
| Methods | 3‐armed randomised controlled trial of personalised feedback during US and counselling to support women to stop smoking in pregnancy. The study was conducted in Women, Infant and Child (WIC) clinics in Houston and Harris County Area, University of Texas Houston Medical School obstetric clinics and the local community (USA). Recruitment years not reported. | |
| Participants | Inclusion criteria: Pregnant women reporting having smoked a cigarette in the past 7 days; age 16 years and older; English speaking, and gestational age between 16 and 26 weeks (to recruit later‐pregnancy continuing smokers who have had the most difficulty stopping smoking for the pregnancy). Exclusion criteria: Not further specified. Recruitment: Via routine prenatal screening and widely distributed advertisements. 4258 women were screened. 360/725 (49.6%) of eligible women agreed to participate and were randomly assigned to 3 conditions: C (BP) = 120, I1 (BP + US) = 120, I2 (MI + US) = 120. Baseline characteristics: Mean number of cigarettes per day: C = 11.72 (8.73), I1 = 11.78 (9.47), I2 = 11.03 (8.14). Partner smoking: C = 68 (68), I1 = 82 (79.6), I2 = 76 (72.4). Baseline cotinine: C = 117, I1 = 116, I2 = 131. Mean gestational age: C = 23.63, I2 = 22.48, I2 = 21.12; Mean age: 24.65,I1 = 25.45, I2 = 25.21; Mean years education: C = 11.40, I1 = 11.37, I 2= 11.63; White: C = 65.22%, I1= 57.02%, I2 = 49.57% (remainder African‐American and Hispanic); Income < $US15,000/yr: C = 49.58%, I1 = 55.85%, I2 = 56.67%. Progress + coding: Low SES. | |
| Interventions | A: Control (BP): Best Practice or “BP” counselling based on the Agency for Healthcare Research Quality practice guidelines for identifying patients who smoke and intervening for smoking cessation (5A's and 5R's). Nurses trained and instructed to keep counselling to 10‐15 mins. Participants were also given American Cancer Society literature on prenatal smoking cessation and the toll‐free number for the quit smoking hotline. B: Intervention 1: BP + US feedback sessions lasting approximately 30 mins. In addition to providing routine US results, the US session was designed to provide information regarding the effect of cigarette smoke on the fetus using a motivational style. The sonographers received 2 hours of training and a laminated prompt card. Smoking risk messages were incorporated into discussion. C: Intervention 2: BP + US + MI consisting of 1 45‐ to 50‐min, face‐to‐face, individual counselling session conducted immediately after the US; 1 personalised feedback letter mailed 1 week later; and 1 follow‐up counselling session conducted via telephone 2 weeks subsequent to the initial session, provided by master's level counsellors. Elements of the transtheoretical model were included and smoking in the household and social networks were also addressed. Main intervention strategy: Feedback (single intervention) compared to a less intensive intervention. Control compared with Intervention 1 (arm B) in this study ID. Intensity: Frequency (C = 2, I = 2), Duration (C = 1, I = 2). Intervention provided by dedicated study staff: Efficacy study. | |
| Outcomes | Biochemically validated smoking cessation at 8 months gestation (late pregnancy*). 'Predictors of abstinence' including: Stages of change, depression (Beck's Depression Inventory), baseline smoking, ethnicity, and social networks reported. | |
| Notes | Concerns about potential distress with the USs intervention were considered in a pilot study of 30 women (Groff 2005) indicated no significant increase in anxiety post‐US. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | A block randomisation method, using blocks of 6 (2 per condition), was used to generate 360 slots, 120 per intervention group. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | Attrition:16/360 (4.4%), C = 6, I1 = 5, I2 = 5 (reasons not reported). Analyses were conducted using an ITT approach with all randomised participants included in the baseline and those lost to follow‐up treated as continued smoking. |
| Selective reporting (reporting bias) | Low risk | Primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Self‐reported smoking status biochemically validated using salivary cotinine (< 20 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel to counselling intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Outcome assessor blinding not reported. |
| Incomplete implementation | Unclear risk | Procecss evaluation not reported. |
| Equal baseline characteristics in study arms | Low risk | Treatment group differences only for gestational age at baseline. |
| Contamination of control group | Low risk | Low risk of contamination as counselling provided by specialist counsellors, not accessible to the control group. |
| Methods | 3‐armed randomised controlled trial of personalised feedback during US and counselling to support women to stop smoking in pregnancy. The study was conducted in Women, Infant and Child (WIC) clinics in Houston and Harris County Area, University of Texas Houston Medical School obstetric clinics and the local community (USA). Recruitment years not reported. | |
| Participants | Inclusion criteria: Pregnant women reporting having smoked a cigarette in the past 7 days; age 16 years and older; English speaking, and gestational age between 16 and 26 weeks (to recruit later‐pregnancy continuing smokers who have had the most difficulty stopping smoking for the pregnancy). Exclusion criteria: Not further specified. Recruitment: Via routine prenatal screening and widely distributed advertisements. 4258 women were screened. 360/725 (49.6%) of eligible women agreed to participate and were randomly assigned to 3 conditions: C (BP) = 120, I1 (BP + US) = 120, I2 (MI + US) = 120. Baseline characteristics: Mean number of cigarettes per day: C = 11.72 (8.73), I1 = 11.78 (9.47), I2 = 11.03 (8.14). Partner smoking: C = 68 (68), I1 = 82 (79.6), I2 = 76 (72.4). Baseline cotinine: C = 117, I1 = 116, I2 = 131. Mean gestational age: C = 23.63, I2 = 22.48, I2 = 21.12; Mean age: 24.65,I1 = 25.45, I2 = 25.21; Mean years education: C = 11.40, I1 = 11.37, I 2= 11.63; White: C = 65.22%, I1= 57.02%, I2 = 49.57% (remainder African‐American and Hispanic); Income < $US15,000/yr: C = 49.58%, I1 = 55.85%, I2 = 56.67%. Progress + coding: Low SES. | |
| Interventions | A: Control (BP): Best Practice or “BP” counselling based on the Agency for Healthcare Research Quality practice guidelines for identifying patients who smoke and intervening for smoking cessation (5A's and 5R's). Nurses trained and instructed to keep counselling to 10‐15 mins. Participants were also given American Cancer Society literature on prenatal smoking cessation and the toll‐free number for the quit smoking hotline. B: Intervention 1: BP + US feedback sessions lasting approximately 30 mins. In addition to providing routine US results, the US session was designed to provide information regarding the effect of cigarette smoke on the fetus using a motivational style. The sonographers received 2 hours of training and a laminated prompt card. Smoking risk messages were incorporated into discussion. C: Intervention 2: BP + US + MI consisting of 1 45‐ to 50‐min, face‐to‐face, individual counselling session conducted immediately after the US; 1 personalised feedback letter mailed 1 week later; and 1 follow‐up counselling session conducted via telephone 2 weeks subsequent to the initial session, provided by master's level counsellors. Elements of the transtheoretical model were included and smoking in the household and social networks were also addressed. Main intervention strategy: Feedback (multiple intervention) compared to a less intensive intervention. Control compared with intervention 2 (arm c) in this study ID. Intensity: Frequency (C = 2, I = 4), Duration (C = 1, I = 3). Intervention provided by dedicated study staff: Efficacy study. | |
| Outcomes | Biochemically validated smoking cessation at 8 months gestation (late pregnancy*). 'Predictors of abstinence' including: Stages of change, depression (Beck's Depression Inventory), baseline smoking, ethnicity, and social networks reported. | |
| Notes | Concerns about potential distress with the USs intervention were considered in a pilot study of 30 women (Groff 2005) indicated no significant increase in anxiety post‐US. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | A block randomisation method, using blocks of 6 (2 per condition), was used to generate 360 slots, 120 per intervention group. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | Attrition:16/360 (4.4%), C = 6, I1 = 5, I2 = 5 (reasons not reported). Analyses were conducted using an ITT approach with all randomised participants included in the baseline and those lost to follow‐up treated as continued smoking. |
| Selective reporting (reporting bias) | Low risk | Primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Self‐reported smoking status biochemically validated using salivary cotinine (< 20 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel to counselling intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Outcome assessor blinding not reported. |
| Incomplete implementation | Unclear risk | Procecss evaluation not reported. |
| Equal baseline characteristics in study arms | Low risk | Treatment group differences only for gestational age at baseline. |
| Contamination of control group | Low risk | Low risk of contamination as counselling provided by specialist counsellors, not accessible to the control group. |
| Methods | Randomised controlled trial of computer‐generated messages to support women to stop smoking in pregnancy. Study conducted in 2 university hospitals in North Carolina and Michigan (USA), with recruitment from December 1996 to December 1997. | |
| Participants | Inclusion criteria: Women who have "smoked 100 cigarettes in their lifetime and still smoking" or "had quit since becoming pregnant". Exclusion criteria: Not further specified. Recruitment: Unclear how many women screened during first prenatal visit. using a self‐administered computer screening program. 173 women randomised (C = 85, I = 88). Baseline characteristics: Mean cigarettes per day before pregnancy: C = 18.7, I = 20.3; current mean cigarettes per day: C = 11.8, I = 12.9; Mean cotinine: C = 2597, I = 2701; Mean smokers in household: C = 1.1, I = 1.0. Mean age: C = 26.6, I = 25.5; Mean education: C = 12.5, I = 12.5; White: C = 81.2%, I = 87.4%. Progress + coding: None. | |
| Interventions | Control: Received "a pregnant woman's guide to quit smoking" at the first visit. Intervention: Entered personal data into a hand‐held computer at AN visits, which subsequently generated personalised tailored messages, which were posted to the woman. Main intervention strategy: Health education (single intervention) compared to less intensive intervention. Intensity: Frequency (C = I, I = 6), Duration (C = 1, I = 2). Unclear if intervention provided by dedicated project or existing staff as technological intervention. | |
| Outcomes | Biochemically validated smoking cessation at 6 weeks postpartum* (0‐5 months pp). Biochemically validated cessation at 24/40 gestation ('mid‐term') and self‐reported cessation 3 months postpartum but outcomes not reported. Mean cigarettes per day and cotinine concentrations collected and reported as 'not significant' but actual figures not reported. Participant evaluation of using hand‐held computers and reactions to computerised materials. | |
| Notes | Numbers in paper inconsistent: I = 88, C = 85 in methods section, I = 104, C = 87 in results section. No justification for change of denominators. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | By computer algorithm. |
| Allocation concealment (selection bias) | Unclear risk | Not described. |
| Incomplete outcome data (attrition bias) | High risk | Outcome data (C = 87, I = 104) are inconsistent with figures reported as randomised in methods and baseline data table (C = 85, I = 88). If comparing outcome data using ITT and excluding those 'lost to follow‐up' it appears that more than 30% of the control group (30/87) were lost to follow‐up. In this review we have used the ITT data (C = 87, I = 104) as the denominator. |
| Selective reporting (reporting bias) | High risk | Results are conflicting and actual figures for pregnancy (24/40) are not reported, nor are figures for mean cigarettes per day or cotinine concentrations. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Urinary cotinine analysis at 24 weeks' gestation and at 6 weeks postpartum (cut‐off < 80 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Participants and personnel not blinded to intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Process evaluation not reported. |
| Equal baseline characteristics in study arms | Low risk | Baseline comparisons revealed no significant differences in age, race, education, number of cigarettes smoked before pregnancy, and baseline stage of change. |
| Contamination of control group | Low risk | Technological intervention so contamination unlikely. |
| Methods | Randomised controlled trial (pilot study) of home‐based MI to support women to stop smoking in pregnancy. Study conducted in a Glasgow Hospital, Scotland (UK), with recruitment from March to May 1997. | |
| Participants | Inclusion criteria: Women who identified as smokers on a questionnaire at AN clinic booking. Exclusion criteria: Not further specified. 133/393 (34%) women screened identified as smokers and 100/133 (75%) agreed to participate and were randomised (C =5 0, I = 50). Baseline characteristics: Mean cigarettes per day pre‐pregnancy C = 18.1, I = 19.6; current mean cigarettes per day C = 13.2, I = 14.8; partner smoking: C = 82%, I = 90%; Mean cotinine C = 126 ng/mL, I = 136 ng/mL. Mean age: C = 25.9, I = 26.6; 76% 'severely deprived' participants. Progress + coding: Low SES. | |
| Interventions | Control: Received usual advice from their prenatal providers, which should include information about smoking. Intervention: Received 2 to 5 MI sessions (mean 2.6 hours), based on stages of change, in the clients' home conducted by a midwife with 3 weeks training in smoking cessation counselling. Main intervention strategy: Counselling (single intervention) compared to UC. Intensity: Frequency: (C = 0, I = 4), Duration (C = 0, I = 4). UC intensity: F = 1, D = 1. Intervention provided by dedicated study staff: Efficacy study. | |
| Outcomes | Biochemically validated smoking cessation at >= 27/40 (late pregnancy*). >= 50% reduction in cotinine* Mean birthweight*, preterm births*, stillbirths*. Ranking interviews measured movement around the 'cycle of change'. Detailed evaluation of participant and midwifery views of interventions. | |
| Notes | SDs for mean birthweight were not reported, therefore we calculated a mean SD from 13 studies with available birthweight SDs (578) to include in this review, as recommended by the cochrane handbook | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Random numbers stratified by deprivation. |
| Allocation concealment (selection bias) | Low risk | Group allocation by telephone. |
| Incomplete outcome data (attrition bias) | Low risk | Low attrition (2%). Some missing data for cotinine validation. Smoking outcome results reported for all of those randomised, and those with missing data counted as continuing smokers in this review. |
| Selective reporting (reporting bias) | Low risk | Detailed outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Serum cotinine levels measured. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel to counselling intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | Good process evaluation of implementation quality according to rating tool, showed 79% of women in the intervention group received at least 2 counselling sessions. |
| Equal baseline characteristics in study arms | Low risk | No apparent difference. |
| Contamination of control group | Low risk | Specific counsellors provided intervention at home so contamination unlikely. Less than 20% of the control group recalled being given smoking information at the time of booking. |
| Methods | Randomised controlled trial of home‐based counselling to support women to stop smoking in pregnancy. Study conducted in 2 hospitals in Glasgow, Scotland (UK), with recruitment from March 2001 to May 2003. | |
| Participants | Inclusion criteria: Women reporting smoking at prenatal booking visit and less than or equal to 24 weeks' gestation. Exclusion criteria: Not further specified. Recruitment: 762/1684 (45%) eligible women agreed to participate (C = 411, I = 351). Baseline characteristics: Current mean cigarettes per day: C = 11.3, I = 11.7; At least 1 other smoker in house: C = 66%, I = 65%. Mean age: C = 26.9, I = 26.5; Most deprived social category (6‐7): C = 73%, I = 69%. Progress + coding: Low SES. | |
| Interventions | Control: Midwives provided standard health promotion including information on smoking in pregnancy from a book given to all women in pregnancy in Scotland. Intervention: Women also were offered 2 to 5 additional home visits of about 30 mins duration from the same study midwife. Main intervention strategy: Counselling (single intervention) compared to UC. Intensity: Frequency: (C = 0, I = 4), Duration (C = 0, I = 4). UC intensity: F = 1, D = 1. Intervention provided by dedicated study staff: Efficacy study. | |
| Outcomes | Biochemically validated and self‐reported quitting soon after the routine 36 week AN visit (late pregnancy*), reduction (mean cotinine*, and biochemically validated, which was at least half baseline measurement*), and increased smoking, mean birthweight*, preterm delivery*, very LBW*, LBW*, neonatal death*, stillbirths*, and admission to NICU*. Data collected on other adverse events including AN admissions, miscarriage, termination of pregnancy, and assisted delivery. Discussion of participant and provider views of intervention and thorough process evaluation showed good implementation. | |
| Notes | Sample size calculated by recruitment to achieve sufficient power not able to be achieved. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Stratified central randomisation. |
| Allocation concealment (selection bias) | Low risk | Group allocation provided by central administrator. |
| Incomplete outcome data (attrition bias) | Low risk | 29/762 (4%) women lost to follow‐up: fetal loss = 6 (C = 2, I = 4) were excluded from this analysis; no late interview or cotinine = 10 (C = 5, I = 5), Not traceable 12 (C = 7, I = 5). Some missing data for cotinine validation. All randomised participants (except fetal losses) included in smoking outcomes, and those with missing data counted as continuing smokers. |
| Selective reporting (reporting bias) | Low risk | Detailed outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Serum cotinine (cut‐off < 13.7 ng/mL) or salivary cotinine (cut‐off < 14.2 ng/mL) used to validate self‐reported abstinence. |
| Blinding of participants and personnel (performance bias) | High risk | Midwife intervention, with caregivers not blinded. |
| Blinding of outcome assessment (detection bias) | Low risk | 'A second administrator, blind to the random allocation, established a primary outcome'. |
| Incomplete implementation | High risk | 26% of women did not have any home visits. |
| Equal baseline characteristics in study arms | Low risk | No apparent major difference noted. |
| Contamination of control group | Low risk | Research midwives provided the intervention. |
| Methods | This 2‐armed randomised controlled trial, aimed to assess the efficacy of financial incentives added to routine pregnancy stop smoking services. This study was conducted in Greater Glasgow, Scotland, UK between December 2011 to February 2013 with follow‐up occurring in September 2013. | |
| Participants | Inclusion criteria: Women were eligible if they were smokers with an exhaled CO level of at least 7 ppm, aged 16 years or more, less than 24 weeks pregnant, resident in NHS Greater Glasgow and Clyde, and able to understand and speak English for telephone consent. Exclusion criteria: Not stated. Recruitment: 612/1722= 35.5% women agreed to participate (C = 306 I = 306). Women were recruited through NHS stop smoking services. Baseline characteristics: Mean Fagerstrom score (C = 5.32 I = 4.85), partner smokes (C = 66.3 I = 59) Mean age at delivery (C = 27.66 I = 28.27). Progress + coding: None. | |
| Interventions | Control: The control group was offered routine specialist pregnancy support by the stop smoking services, which included the offer of a face‐to‐face appointment to discuss smoking and cessation and, for those who attended and set a quit date, the offer of free NRT for 10 weeks provided by pharmacy services, and 4 weekly support phone calls. Intervention: The incentives group was offered the same routine support plus up to £400 of shopping vouchers (Love2shop) for engaging with stop smoking services or for quitting during pregnancy, or both. Intervention participants received £50 of vouchers if they attended their face‐to‐face appointment and set a quit date. Confirmed quitters were sent a further £50 voucher. 12 weeks after stopping smoking, women in the incentives group who were quitters at 4 weeks were contacted by stop smoking services (routine practice) and, if confirmed to be abstinent CO breath test result < 10 ppm), were sent a £100 voucher. A research nurse visited self‐reported quitters to collect a CO level, and saliva and urine for cotinine estimation. Women in the incentives group who were confirmed as abstinent by the CO breath test (< 10 ppm) were sent a final £200 voucher. Main Intervention strategy: Incentives (single) v UC Intensity: Frequency (C = 0 I = 4) Duration (C = 0 I = 4). | |
| Outcomes | Cotinine verified cessation at 34‐38 weeks' gestation*, self‐reported quit at 6 months postpartum*, preterm birth*, mean birthweight*. Stillbirths and miscarriages combined so not included in this review. Engagement. Cost‐effectiveness. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | The Glasgow Clinical Trials Unit embedded the randomisation in the trial database using randomised permuted blocks, with a block length of 4, thus facilitating equal distribution of clients between the interventions. |
| Allocation concealment (selection bias) | Low risk | Allocation was concealed from staff and clients until after consent and recruitment. |
| Incomplete outcome data (attrition bias) | Low risk | No evidence of unequal attrition in study arms and ITT analysis was used for missing data. 15% were lost to follow‐up and were counted as smokers. |
| Selective reporting (reporting bias) | Low risk | Both primary and secondary outcomes are reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Smoking is biochemically validated, with cotinine verified cessation through saliva (< 14.2 ng/mL) or urine < 44.7 ng/mL |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and providers to this intervention. |
| Blinding of outcome assessment (detection bias) | Low risk | Helpline staff, who ascertained the primary outcome, self report of smoking status in late pregnancy, were blind to allocation status. |
| Incomplete implementation | Unclear risk | 15% were lost to follow‐up and were counted as smokers. |
| Equal baseline characteristics in study arms | Low risk | Baseline characteristics appear even in both groups. |
| Contamination of control group | Low risk | Incentives were the main intervention component, therefore contamination more likely. |
| Methods | Randomised controlled trial of counselling intervention to support women to stop smoking and prevent relapse in pregnancy. Study conducted in a large public AN clinic, in Rotunda Ireland, with recruitment during 3 months in 1995. | |
| Participants | Inclusion criteria: Women who 'currently smoke' or had spontaneously quit since becoming pregnant. Exclusion criteria: Non‐viable pregnancy identified at first visit or intending to deliver at another hospital. Recruitment: 967/524 (54%) women attending the public clinic were smokers. 418/518 (81%) eligible women agreed to participate and were randomised (C = 209, I = 209). Baseline characteristics: Current smoker: C = 192, I = 203; Spontaneous quitter: C = 17, I = 6; 34% smoked more than 20 cigarettes per day currently; Partner smoking: C = 74%, I = 69.9%. < 21 years age C = 17%, I = 24%; Mean gestation at first visit I = 15.5, C = 15.3; Not living with partner C = 39.2%, I = 42.6%; age finished education C = 16.1, I = 16.0; Lower social class C = 71.5%, I = 70.9%. Progress + coding: Low SES. | |
| Interventions | Control: Routine prenatal advice on a range of health issues, from midwives and obstetricians. Intervention: As for the control group + (i) structured 1 to 1 counselling by a trained facilitator (based on stages of change theory); (ii) partners invited to be involved in the program; (iii) an information pack (developed in collaboration with a focus group of women), which included a self‐help booklet; (iv) and invited to join a stop smoking support group. A CO monitor was available for the intervention group, to quantify smoking habit and act as a motivational tool. Main intervention strategy: Counselling (tailored) compared to UC. Intensity: Frequency: (C = 0, I = 5); Duration (C = 0, I = 2). UC intensity: F = 1, D = 1. Intervention provided by dedicated study staff: Efficacy study. | |
| Outcomes | Biochemically validated smoking cessation* and relapse prevention* at delivery (late pregnancy) and 3 months postpartum among baseline smokers* and spontaneous quitter. Mean cigarettes per day at delivery*, reduction in daily cigarettes since first visit, quit attempts, comparisons of quitters and non quitters at various stages. Infant outcomes at 3 months postpartum: neonatal deaths, attendance at GP; attendance or admission to hospital. | |
| Notes | Detailed process analysis and participant feedback of program implementation. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Random number tables with restricted randomisation in groups of 10. |
| Allocation concealment (selection bias) | Low risk | Sealed opaque envelopes. |
| Incomplete outcome data (attrition bias) | Unclear risk | 31/418 (7%) attrition at delivery (I = 13/209 or 6.2%, C 18/209 or = 8.6%). Miscarriage (7), delivered elsewhere (3), moved overseas (2), changed care provider (7) or never returned to Rotunda hospital after first visit (12), and were excluded from this analysis. All other women lost to follow‐up counted as continuing smokers in this review. |
| Selective reporting (reporting bias) | Low risk | All outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Exhaled CO measurement on 145/209 women on postnatal ward (cut‐off < 4 ppm). Presume smoking outcomes reported are those biochemically validated although this is not explicitly stated. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and study personnel to counselling intervention. Intervention provided by trained facilitator, with staff unaware of allocation. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Detailed process evaluation describes how women rarely initiated contact at subsequent visits and the groups sessions were poorly attended. |
| Equal baseline characteristics in study arms | High risk | Intervention group were less likely to have spontaneously quit, or be employed. |
| Contamination of control group | Low risk | Research facilitator provided intervention. |
| Methods | Randomised controlled trial of a computer‐delivered brief intervention 'Video Doctor' to support women to stop smoking in pregnancy. Study conducted as part of 'Health in Pregnancy' study in 5 community prenatal clinics in San Francisco Bay Area (USA), with recruitment from 2006 to December 2007. | |
| Participants | Inclusion criteria: Pregnant women 'smoking in the past 30 days' who were English‐speaking, 18 years or older, and less than 26 weeks pregnant. Exclusion criteria: Not further specified. Recruitment: 1208 women were screened for eligibility in the prenatal clinic waiting rooms and 114 refused (91% participation in screening). 42/410 (10%) eligible women identified as smokers on a risk assessment using a laptop computer via a low‐literacy computerised interview with audio voiceover, and were randomised (C = 19, I = 23). Baseline characteristics: Current mean cigarettes per day I = 6.8, C = 6.7. Mean age C = 26.8, I = 27.5; White C = 31.6%, I = 17.4% (remaining Hispanic, Back or 'other'); Less than high school C = 21.1%, I = 26.1%; Married C = 26.3%, I = 47.8%. Progress + coding: None. | |
| Interventions | Control: Received the clinic’s UC and did not interact with the 'Video Doctor' program. All participants received a gift card ($30‐$50) for completing assessments. Intervention: Participants received tailored advice from 'Video Doctor', a multimedia interactive intervention delivered on a laptop computer via a secure Internet connection. An actor‐portrayed Video Doctor delivered interactive risk‐reduction messages designed to simulate an ideal discussion with a prenatal health care provider who provided non‐judgmental counselling following several key principles of MI. At the conclusion of each intervention session, the program automatically printed 2 documents: (a) a cueing sheet for providers, which offered a summary of the patient’s risk profile and suggested risk‐reduction counselling statements; and (b) an educational worksheet for participants with questions for self‐reflection, harm reduction tips, and local resources. The cueing sheet was placed in the patient’s medical record for the provider’s use during the prenatal appointment. Main intervention strategy: Counselling (multiple intervention) compared to UC. Intensity: Frequency (C = 0, I = 3), Duration (C = 0, I = 2). Technological intervention which prompted UC providers: Effectiveness study. | |
| Outcomes | Self‐reported 30‐day abstinence after 1 month and 2 months (late pregnancy*). Mean reduction in cigarettes smoked per day and days smoked. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Women reporting risks were stratified by risk combination and randomly assigned by the computer to intervention or UC groups. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | Attrition: I = 5/23 (22%), C = 5/19 (26%) at 1‐month follow‐up and I = 9/23 (39%), C = 13/19 (32%) at 2‐month follow‐up (reasons not reported). All randomised participants included in analysis and women lost to follow‐up treated as continuing smokers in this review. |
| Selective reporting (reporting bias) | Low risk | Primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Self‐reported smoking cessation outcomes only ‐ no biochemical validation of smoking status. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel as intervention includes counselling component. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Blinding of outcome assessor not reported. |
| Incomplete implementation | Low risk | Only 3 women in the UC group did not recall receiving provider advice. |
| Equal baseline characteristics in study arms | Low risk | Similar baseline characteristics. |
| Contamination of control group | Unclear risk | Some risk of contamination between study arms as same provider delivering counselling to intervention and control groups. Process evaluation showed 77.8% intervention group received 2 provider advice sessions, compared to 21.4% control group. |
| Methods | 3‐armed randomised controlled trial of contingent incentives to support women to stop smoking in pregnancy. Study conducted in the Center for Addiction and Pregnancy Treatment, at the Johns Hopkins Bayview Medical Center, Baltimore (USA), with recruitment from May 2005 to January 2009. | |
| Participants | Inclusion criteria: Requiring methadone during pregnancy, nicotine dependent or smoking 10 or more cigarettes daily, aged 18 years or older, <= 30 weeks' gestation, and capable of providing informed consent. Exclusion criteria: NRT. Recruitment: 1072/1181 women screened smoked (90.7%). 125/1072 were eligible, and 102/125 (82%) agreed to participate, and were randomised to 3 conditions (C = 32, I1 (non‐contingent incentives) = 28, I2 (contingent incentives) = 42). Baseline characteristics: Current mean cigarettes per day = 18.0. Mean age 30.8 years; 65% Caucasian; 11.1 mean years education; 85.3% currently single. 94.7% unemployed. Progress + coding: Low SES. | |
| Interventions | A: Control: As part of UC, inpatients at the centre were provided with specific information about the adverse effects associated with cigarette smoking for the mother and the infant. In addition, patients were provided with educational materials about risks of smoking during pregnancy. During follow‐up obstetric appointments, patients were asked routinely about their cigarette smoking and commended on efforts to abstain. TAU participants were informed that they would be compensated for providing urine and breath samples, but that they would not earn incentives as part of their study participation. B: Intervention 1 (non‐contingent incentives): Participants were informed that they had the chance to earn vouchers, but whether they earned a voucher and the amount they earned was determined by an already generated schedule and thus was not linked to their own cigarette smoking. NCBI participants were required to leave CO and urine samples to receive any voucher earnings generated by the 'yoked' schedule, for 12 weeks or until delivery. C: Intervention 2 (contingent incentives): Incentives contingent upon cigarette smoking reduction or abstinence for a period of 12 weeks or until delivery. Smoking targets were minimal during the initial weeks of intervention, and increased gradually to ensure adequate learning and reinforcement. Incentives could be earned for each sample left on Monday, Wednesday and Friday (3 samples per week) if the following reduction and abstinence targets were met: week 1: any reduction; weeks 2–4: 10% reduction; weeks 5–7: 25% reduction; weeks 8–9: 50% reduction; week 10–11: 75% reduction; and week 12 until delivery: abstinence (CO < 4 ppm.). Participants had the opportunity to earn a $7.50 voucher for the first smoking reduction target, and the value of the voucher increased by $1/day for each consecutive target met throughout the 12‐week incentive period to a maximum of $41.50. If a contingent participant failed to meet the tobacco use reduction target during the 12‐week incentive period, she earned $0 for that sample and the incentive schedule was reset to the original voucher value of $7.50. If the participant again met the target reduction on 5 consecutive occasions, she earned vouchers at the previously attained level. Main intervention strategy: Incentives (single intervention) compared to UC. Non‐Contingent incentives (arm b) compared to UC in this study ID. Intensity: Frequency: (C = 0, I = 6), Duration (C = 0, I = 5). Intervention provided by dedicated project staff: Efficacy study. | |
| Outcomes | Biochemically validated point prevalence abstinence after 12 weeks of intervention (late pregnancy*); 75% cotinine reduction (> 50% reduction*); mean cotinine*. Mean cigarettes per day 1 and 3 months post intervention and 6 weeks postpartum, however only 6 weeks postpartum mean cigarettes per day reported for arm B so this outcome is not included for this arm in this review. Mean birthweight*, preterm births*, LBW*, NICU admissions*. Spontaneous abortion, length of hospital stay, mean gestational age at delivery, mean 1‐ and 5‐min Apgars, urine toxicology and treatment for NAS. Comparisons with non‐contingent incentives (arm 2) are also reported. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | States patients were 'randomly assigned' to 1 of 3 conditions. |
| Allocation concealment (selection bias) | Unclear risk | Not stated. |
| Incomplete outcome data (attrition bias) | High risk | 33% attrition (34/102) for pregnancy and birth outcomes and no explanation as to reasons for missing data. Unclear whether all women randomised were included in the outcome assessment, as percentage results only are reported. Assume all persons not meeting 'nonsmoking targets' (p1872) are counted as continuing smokers. |
| Selective reporting (reporting bias) | Low risk | Primary outcomes appear to be reported, except smoking outcomes postpartum. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Exhaled CO (< 4 ppm) validation to evaluate changes during in‐patient treatment phase used in this study as not smoking. Urine cotinine (cut‐off 200 ng/mL) also collected but unclear if used for validation. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel to incentives intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not stated if outcome assessment was blinded. |
| Incomplete implementation | Low risk | This was a well‐accepted intervention with high rates of participation among all 3 conditions. |
| Equal baseline characteristics in study arms | Low risk | The conditions did not differ significantly on demographic, pre‐treatment or baseline cigarette smoking measures. |
| Contamination of control group | Low risk | Unlikely given the design of the study. |
| Methods | 3‐armed randomised controlled trial of contingent incentives to support women to stop smoking in pregnancy. Study conducted in the Center for Addiction and Pregnancy Treatment, at the Johns Hopkins Bayview Medical Center, Baltimore (USA), with recruitment from May 2005 to January 2009. | |
| Participants | Inclusion criteria: Requiring methadone during pregnancy, nicotine dependent or smoking 10 or more cigarettes daily, aged 18 years or older, <= 30 weeks' gestation, and capable of providing informed consent. Exclusion criteria: NRT. Recruitment: 1072/1181 women screened smoked (90.7%). 125/1072 were eligible, and 102/125 (82%) agreed to participate, and were randomised to 3 conditions (C = 32, I1 (non‐contingent incentives) = 28, I2 (contingent incentives) = 42). Baseline characteristics: Current mean cigarettes per day = 18.0. Mean age 30.8 years; 65% Caucasian; 11.1 mean years education; 85.3% currently single. 94.7% unemployed. Progress + coding: Low SES. | |
| Interventions | A: Control: As part of UC, inpatients at the centre are provided with specific information about the adverse effects associated with cigarette smoking for the mother and the infant. In addition, patients are provided with educational materials about risks of smoking during pregnancy. During follow‐up obstetric appointments, patients are asked routinely about their cigarette smoking and commended on efforts to abstain. TAU participants were informed that they would be compensated for providing urine and breath samples, but that they would not earn incentives as part of their study participation. B: Intervention 1 (non‐contingent incentives): Participants were informed that they had the chance to earn vouchers, but whether they earned a voucher and the amount they earned was determined by an already generated schedule and thus was not linked to their own cigarette smoking. NCBI participants were required to leave CO and urine samples to receive any voucher earnings generated by the 'yoked' schedule, for 12 weeks or until delivery. C: Intervention 2 (contingent incentives): Incentives contingent upon cigarette smoking reduction or abstinence for a period of 12 weeks or until delivery. Smoking targets were minimal during the initial weeks of intervention, and increased gradually to ensure adequate learning and reinforcement. Incentives could be earned for each sample left on Monday, Wednesday and Friday (3 samples per week) if the following reduction and abstinence targets were met: week 1: any reduction; weeks 2–4: 10% reduction; weeks 5–7: 25% reduction; weeks 8–9: 50% reduction; week 10–11: 75% reduction; and week 12 until delivery: abstinence (CO < 4 ppm.). Participants had the opportunity to earn a $7.50 voucher for the first smoking reduction target, and the value of the voucher increased by $1/day for each consecutive target met throughout the 12‐week incentive period to a maximum of $41.50. If a contingent participant failed to meet the tobacco use reduction target during the 12‐week incentive period, she earned $0 for that sample and the incentive schedule was reset to the original voucher value of $7.50. If the participant again met the target reduction on 5 consecutive occasions, she earned vouchers at the previously attained level. Main intervention strategy: Incentives (single intervention) compared to UC. Contingent incentives (arm c) compared to UC in this study ID. Intensity: Frequency: (C = 0, I = 6), Duration (C = 0, I = 5). Intervention provided by dedicated project staff: Efficacy study. | |
| Outcomes | Biochemically validated point prevalence abstinence after 12 weeks of intervention (late pregnancy*); 75% cotinine reduction (> 50% reduction*); mean cotinine*; mean cigarettes per day 1 and 3 months post intervention* and 6 weeks postpartum. Mean birthweight*, preterm births*, LBW*, NICU admissions*. Spontaneous abortion, length of hospital stay, mean gestational age at delivery, mean 1‐ and 5‐min Apgars, urine toxicology and treatment for NAS. Comparisons with non‐contingent incentives (arm 2) are also reported. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | States patients were 'randomly assigned' to 1 of 3 conditions. |
| Allocation concealment (selection bias) | Unclear risk | Not stated. |
| Incomplete outcome data (attrition bias) | High risk | 33% attrition (34/102) for pregnancy and birth outcomes and no explanation as to reasons for missing data. Unclear whether all women randomised were included in the outcome assessment, as percentage results only are reported. Assume all persons not meeting 'nonsmoking targets' (p1872) are counted as continuing smokers. |
| Selective reporting (reporting bias) | Low risk | Primary outcomes appear to be reported, except smoking outcomes postpartum. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Exhaled CO (< 4 ppm) validation to evaluate changes during in‐patient treatment phase used in this study as not smoking. Urine cotinine (cut‐off 200 ng/mL) also collected but unclear if used for validation. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and personnel to incentives intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not stated if outcome assessment was blinded. |
| Incomplete implementation | Low risk | This was a well‐accepted intervention with high rates of participation among all 3 conditions. |
| Equal baseline characteristics in study arms | Low risk | The conditions did not differ significantly on demographic, pre‐treatment or baseline cigarette smoking measures. |
| Contamination of control group | Low risk | Unlikely given the design of the study. |
| Methods | This 2‐armed randomised controlled trial aimed to determine the effectiveness of a physical activity intervention for smoking cessation during pregnancy. The study was conducted in 13 AN clinics in hospitals in London, Surrey, Kent, and Cheshire, England, UK between April 2009 and November 2012. | |
| Participants | Inclusion criteria: Women wanting to stop smoking, wanting help with stopping smoking, agreeing to set a date for quitting smoking within 1 week of the baseline visit, age Exclusion criteria: Exclusion criteria were medical conditions potentially exacerbated by exercise or advised against exercise by a doctor, inability to provide informed consent or complete questionnaires in English, drug or alcohol dependence, and currently using or wanting to use NRT. Women were recruited irrespective of their current level of physical activity or motivation towards increasing their activity. Recruitment: 789/5513 (14.3%) eligible women agreed to participate (C = 395 I = 393). Women were recruited by phone after their initial visit at their AN clinic. Baseline characteristics: Median No. of cigarettes smoked daily at baseline (C = 10 I = 10) Median Fagerström test of cigarette dependence score (C = 4 I = 4) Partner smokes (C = 261 I = 250) Mean age at leaving full time education (years)* (C = 17.8 I = 18.0). Progress + coding: None. | |
| Interventions | Control: All participants offered 6 weekly sessions of 20 mins of individual behavioural cessation support, starting 1 week before the quit date and ending 4 weeks afterwards. This intervention aimed to support smoking cessation by reinforcing commitment to abstinence and solving women’s problems about maintaining abstinence. It incorporated all 43 behaviour‐change techniques defined in a published taxonomy 16 and as described in the protocol,15 except for the provision of rewards contingent on successfully stopping smoking. The emphasis was on the importance of avoiding lapses, managing withdrawal symptoms and urges to smoke, enhancing self‐confidence, and prevention of relapse. Intervention: Behavioural cessation support plus a physical activity intervention, combining supervised exercise with physical activity consultations. 14 sessions of supervised exercise were offered over 8 weeks; twice a week for 6 weeks then weekly for 2 weeks. At each session, the participants walked at a moderate intensity on a treadmill for up to 30 mins. Immediately before each treadmill session, the women received behavioural support. Main Intervention strategy: Smoking Cessation Intervention: Execercise (single) v UC. Intensity: Frequency (C = 6 I = 6) Duration (C = 4 I = 6). | |
| Outcomes | Biochemically validated abstinence validated by exhaled CO at end of pregnancy* and at four weeks after quit date, self‐reported abstinence by telephone 6 months after birth*, miscarriage, stillbirth*, neonatal death*, mean birthweight (g)*, mean gestational age at delivery, preterm births*, LBW (< 2500 g)*, admission to NICU*, Apgar score at 5 mins, cord blood arterial pH < 7, congenital abnormalities, assisted vaginal delivery, caesarean delivery. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | An independent statistician generated a randomisation list using Stata, with random permuted blocks of random size stratified by recruitment centre, in a 1:1 ratio. At enrolment the sequence was concealed from researchers who confirmed consent and eligibility on an online database before allocation was revealed. |
| Allocation concealment (selection bias) | Low risk | At enrolment the sequence was concealed from researchers who confirmed consent and eligibility on an online database before allocation was revealed. |
| Incomplete outcome data (attrition bias) | Low risk | Analysis was performed on an ITT basis; participants with missing outcome data were assumed to be smoking |
| Selective reporting (reporting bias) | Low risk | Primary and secondary outcomes are reported. |
| Other bias | Low risk | No other bias was detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Self‐reported outcomes of smoking are validated by exhaled CO (< 8 ppm) and salivary cotinine (<10 ng/mL) levels |
| Blinding of participants and personnel (performance bias) | High risk | It was not feasible to mask participants or researchers to group allocation. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Out of the 14 sessions offered in the intervention arm, a median of 4 were completed. |
| Equal baseline characteristics in study arms | Low risk | Baseline characteristics were equal in both study arms. |
| Contamination of control group | Low risk | Intervention was the undertaking of exercise and therefore contamination was unlikely. |
| Methods | Randomised controlled trial of US feedback and cognitive‐behavioural modification, to support women to stop smoking in pregnancy. Study conducted in the National University Hospital, Oslo, Norway (Europe), with recruitment from June 1990 to October 1991. | |
| Participants | Inclusion criteria: Pregnant women attending AN clinic for 18 weeks for US, and still smoking 10 cigarettes per day or more (heavy smokers). Exclusion criteria: Not further specified. Recruitment: Not stated how many women approached or eligible (1800 births/year, study over 15 months). 112 women randomised (C = 56, I = 56). Baseline characteristics: Mean cigarettes per day at 18 weeks' gestation: C = 14.8, I = 12.5. Smoking partner: C = 80%, I = 74%. Mean age: C = 28.4, I = 20.2. Progress + coding: None. | |
| Interventions | Control: Routine 18‐week US and information on the negative effects of smoking and encouragement to quit, reinforced by a pamphlet, provided at the time of the US examination. Main intervention strategy: Feedback (multiple intervention) compared to UC. Intensity: Frequency (C = 0, I = 3), Duration (C = 0, I = 2). UC intensity: F = 1, D = 1. Intervention provided by existing staff: Effectiveness study. | |
| Outcomes | Self‐reported abstinence at delivery (late pregnancy*); self‐reported reduction in smoking at birth* mean cigarettes per day at birth*. Stillbirths* reported in attrition and re‐included in both numerator and denominator for this outcome. | |
| Notes | Process evaluation suggested that the acceptance of the manual was low (mean score 2.6 on a 7‐point scale) and that it was staff involvement which had the most impact. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as "consecutively randomised". |
| Allocation concealment (selection bias) | High risk | Women consecutively randomised into 2 groups. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition: 1 stillbirth in intervention arm excluded from analysis. 7 women who did not return questionnaires (C = 6, I = 1) were not included in the study report but have been re‐included as continuing smokers in this review (C = 56, I = 55). |
| Selective reporting (reporting bias) | Unclear risk | Only smoking outcomes reported. |
| Other bias | Unclear risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | No biochemical validation. |
| Blinding of participants and personnel (performance bias) | High risk | Not feasible to blind participants and providers to educational intervention and US. Although it is unclear if consent was sought so participants may have been blind. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | No process evaluation reported but assume most women received manual and USs. |
| Equal baseline characteristics in study arms | Unclear risk | Intervention group had significantly higher daily smoking on entry. |
| Contamination of control group | High risk | UC providers offering intervention and control components. |
| Methods | Randomised controlled trial of hypnosis to support women to stop smoking during pregnancy. Study conducted in Buskerud Central Hospital in Oslo, Norway (Europe), with recruitment from January 1992 to June 1993. | |
| Participants | Inclusion criteria: Women still smoking at 18‐week US visit. Exclusion criteria: Not further specified. Recruitment: Expected numbers of pregnant smokers were 630. 158 (25%) agreed to participate and were randomised (78, I = 80). Baseline characteristics: Mean cigarettes/day prior to pregnancy I = 15.6, C = 15.0; Mean cigarettes per day at 18 weeks' gestation C = 9.7, I = 11.3; Partner smoking C = 73%, I = 71%. Mean age C = 26.5, I = 27.9. Progress + coding: None. | |
| Interventions | Control: "Routine pregnancy health care". Main intervention strategy: Counselling (single intervention) compared to UC. Intensity: Frequency (C = 0, I = 4); Duration (C = 0, I = 3). Intervention provided by dedicated study staff: Efficacy study. | |
| Outcomes | Self‐reported abstinence at birth (late pregnancy*), mean cigarettes per day at birth*, Self‐reported reduction in smoking* (The SD used in the analysis in this review was calculated from a P value = 0.2 given in the paper) and increase at end of pregnancy, | |
| Notes | Process evaluation did not rate the intervention highly: mean score of 2.05/7. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | The numbers from 1 to 100 were set up in random order, and by drawing lot, the women willing to participate were randomised into the intervention or control group. |
| Allocation concealment (selection bias) | Unclear risk | Women allocated to groups by drawing lots (it was not clear when this took place). |
| Incomplete outcome data (attrition bias) | Unclear risk | Of 80 allocated to intervention, 13 did not receive an appointment in time, and 15 did not attend, and were excluded from the analysis. |
| Selective reporting (reporting bias) | Unclear risk | Only smoking outcomes reported. |
| Other bias | Unclear risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | No biochemical validation. |
| Blinding of participants and personnel (performance bias) | High risk | Psychological intervention, authors state that usual caregivers were not aware of group allocation. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | 28/80 women randomised did not receive the intervention |
| Equal baseline characteristics in study arms | High risk | Significantly more smokers in intervention group at entry. |
| Contamination of control group | Low risk | Dedicated hypnotist provided intervention. |
| Methods | 4‐armed cluster‐randomised controlled trial of counselling interventions to support women to stop smoking in pregnancy. Study conducted in primary healthcare clinics in Malaga, southern Spain, with data collection from 2001‐2003. | |
| Participants | Inclusion criteria: 12/23 community clinics selected to balance neighbourhood SES (low, medium, and high). Women included if less than 15 weeks' gestation and smoked at least 1 cigarette since knowing they were pregnant. Exclusion criteria: not further specified. Recruitment: 12 clinics 'randomly selected', stratified by SES status of neighbourhood. 3 randomly allocated to each study arm, based on SES status (3 levels, low, medium, high: so 1 level each study arm). Clinics balanced across study arms. Women identified in 1999 in a preconceptual program (2932 women screened in 23 clinics ‐ 38% were smokers). 719 eligible smokers from the 12 clinics were invited, of whom 455 agreed to participate (63% participation). 132 women spontaneously quit smoking after baseline and 27 had a spontaneous abortion; both were excluded from the study. 296 women were randomised (C = 54, I1 = 71, I2 = 47, I3 = 124). Baseline characteristics: Mean cigarettes per day before becoming pregnant 20.6 (9.58); Fagerstrom score: 4.78 (SD 5.38). 97.7% married. Education: 4% did not complete junior high school, 45% completed junior level only (9 years), 33% 12 years school, 17% university level. SES: 4.8% high, 24.6% medium/high, 53.4% medium/low, 17.1% low SES. Progress + coding: None. | |
| Interventions | A: Control: UC. All 3 interventions were based on CBT, adapted to pregnant women taking into account factors important to women for smoking and quitting, but differ in intensity (frequency and duration). Main intervention strategy: Counselling (single intervention) compared to UC. Intervention 1 (low intensity) and control (UC) compared in this study ID. Intensity: Frequency (C = 0, I = 2); Duration (C = 0, I = 2). Intervention provided by dedicated study staff: Efficacy study. | |
| Outcomes | Self‐reported mean cigarettes per day in late pregnancy*, Mean exhaled CO, Mean birthweight*. Biochemically validated point prevalence abstinence rates not reported. Breastfeeding rates at 8 weeks postpartum reported. | |
| Notes | Report in Spanish. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Clinics described as 'randomly assigned'. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | High risk | 455 consented and 132 excluded as they spontaneously quit smoking, and further 27 excluded due to spontaneous abortion. |
| Selective reporting (reporting bias) | High risk | Biochemically validated smoking cessation rates, proportion of preterm births, and stages of change outcomes stated as primary and secondary outcomes and not reported. |
| Other bias | High risk | Tried to balance women across study arms and clinics (40 per arm per clinic) but were unable to achieve this. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Exhaled CO validation measured but biochemically confirmed smoking cessation rates not reported. |
| Blinding of participants and personnel (performance bias) | Unclear risk | States clinics were not aware of allocation. |
| Blinding of outcome assessment (detection bias) | Low risk | Outcome assessors blinded. |
| Incomplete implementation | High risk | Only 8% completed the high‐ and medium‐intensity interventions (group sessions). |
| Equal baseline characteristics in study arms | Unclear risk | Baseline characteristics not reported by individual study arm. |
| Contamination of control group | Low risk | Cluster‐randomised trial design minimises risk of contamination. |
| Methods | 4‐armed cluster‐randomised controlled trial of counselling interventions to support women to stop smoking in pregnancy. Study conducted in primary health care clinics in Malaga, southern Spain, with data collection from 2001‐2003. | |
| Participants | Inclusion criteria: 12/23 community clinics selected to balance neighbourhood SES (low, medium, and high). Women included if less than 15 weeks' gestation and smoked at least 1 cigarette since knowing they were pregnant. Exclusion criteria: not further specified. Recruitment: 12 clinics 'randomly selected', stratified by SES status of neighbourhood. 3 randomly allocated to each study arm, based on SES status (3 levels, low, medium, high: so 1 level each study arm). Clinics balanced across study arms. Women identified in 1999 in a preconceptual program (2932 women screened in 23 clinics ‐ 38% were smokers). 719 eligible smokers from the 12 clinics were invited, of whom 455 agreed to participate (63% participation). 132 women spontaneously quit smoking after baseline and 27 had a spontaneous abortion; both were excluded from the study. 296 women were randomised (C = 54, I1 = 71, I2 = 47, I3 = 124). Baseline characteristics: Mean cigarettes per day before becoming pregnant 20.6 (9.58); Fagerstrom score: 4.78 (SD 5.38). 97.7% married. Education: 4% did not complete junior high school, 45% completed junior level only (9 years), 33% 12 years school, 17% university level. SES: 4.8% high, 24.6% medium/high, 53.4% medium/low, 17.1% low SES. Progress + coding: None. | |
| Interventions | A: Control: UC. All 3 interventions were based on CBT, adapted to pregnant women taking into account factors important to women for smoking and quitting, but differ in intensity (frequency and duration). Main intervention strategy: Counselling (single intervention) compared to UC. Intervention 2 (medium intensity) and control (UC) compared in this study ID. Intensity: Frequency (C = 0, I = 4); Duration (C = 0, I = 5). Intervention provided by dedicated study staff: Efficacy study. | |
| Outcomes | Self‐reported mean cigarettes per day in late pregnancy*, Mean exhaled CO, Mean birthweight*. Biochemically validated point prevalence abstinence rates not reported. Breastfeeding rates at 8 weeks postpartum reported. | |
| Notes | Report in Spanish. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Clinics described as 'randomly assigned'. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | High risk | 455 consented and 132 excluded as they spontaneously quit smoking, and further 27 excluded due to spontaneous abortion. |
| Selective reporting (reporting bias) | High risk | Biochemically validated smoking cessation rates, proportion of preterm births, and stages of change outcomes stated as primary and secondary outcomes and not reported. |
| Other bias | High risk | Tried to balance women across study arms and clinics (40 per arm per clinic) but were unable to achieve this. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Exhaled CO validation measured but biochemically confirmed smoking cessation rates not reported. |
| Blinding of participants and personnel (performance bias) | Unclear risk | States clinics were not aware of allocation. |
| Blinding of outcome assessment (detection bias) | Low risk | Outcome assessors blinded. |
| Incomplete implementation | High risk | Only 8% completed the high‐ and medium‐intensity interventions (group sessions). |
| Equal baseline characteristics in study arms | Unclear risk | Baseline characteristics not reported by individual study arm. |
| Contamination of control group | Low risk | Cluster‐randomised trial design minimises risk of contamination. |
| Methods | 4‐armed cluster‐randomised controlled trial of counselling interventions to support women to stop smoking in pregnancy. Study conducted in primary health care clinics in Malaga, southern Spain, with data collection from 2001‐2003. | |
| Participants | Inclusion criteria: 12/23 community clinics selected to balance neighbourhood SES (low, medium, and high). Women included if less than 15 weeks' gestation and smoked at least 1 cigarette since knowing they were pregnant. Exclusion criteria: not further specified. Recruitment: 12 clinics 'randomly selected', stratified by SES status of neighbourhood. 3 randomly allocated to each study arm, based on SES status (3 levels, low, medium, high: so 1 level each study arm). Clinics balanced across study arms. Women identified in 1999 in a preconceptual program (2932 women screened in 23 clinics ‐ 38% were smokers). 719 eligible smokers from the 12 clinics were invited, of whom 455 agreed to participate (63% participation). 132 women spontaneously quit smoking after baseline and 27 had a spontaneous abortion; both were excluded from the study. 296 women were randomised (C = 54, I1 = 71, I2 = 47, I3 = 124). Baseline characteristics: Mean cigarettes per day before becoming pregnant 20.6 (9.58); Fagerstrom score: 4.78 (SD 5.38). 97.7% married. Education: 4% did not complete junior high school, 45% completed junior level only (9 years), 33% 12 years school, 17% university level. SES: 4.8% high, 24.6% medium/high, 53.4% medium/low, 17.1% low SES. Progress + coding: None. | |
| Interventions | A: Control: UC. All 3 interventions were based on CBT, adapted to pregnant women taking into account factors important to women for smoking and quitting, but differ in intensity (frequency and duration). Main intervention strategy: Counselling (multiple intervention) compared to UC. Intervention 3 (high intensity) and control (UC) compared in this study ID. Intensity: Frequency (C = 0, I = 6); Duration (C = 0, I = 5). Intervention provided by dedicated study staff: Efficacy study. | |
| Outcomes | Self‐reported mean cigarettes per day in late pregnancy*, Mean exhaled CO, Mean birthweight*. Biochemically validated point prevalence abstinence rates not reported. Breastfeeding rates at 8 weeks postpartum reported. | |
| Notes | Report in Spanish. | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Clinics described as 'randomly assigned'. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | High risk | 455 consented and 132 excluded as they spontaneously quit smoking, and further 27 excluded due to spontaneous abortion. |
| Selective reporting (reporting bias) | High risk | Biochemically validated smoking cessation rates, proportion of preterm births, and stages of change outcomes stated as primary and secondary outcomes and not reported. |
| Other bias | High risk | Tried to balance women across study arms and clinics (40 per arm per clinic) but were unable to achieve this. |
| Biochemical validation of smoking abstinence (detection bias) | Unclear risk | Exhaled CO validation measured but biochemically confirmed smoking cessation rates not reported. |
| Blinding of participants and personnel (performance bias) | Unclear risk | States clinics were not aware of allocation. |
| Blinding of outcome assessment (detection bias) | Low risk | Outcome assessors blinded. |
| Incomplete implementation | High risk | Only 8% completed the high and medium intensity interventions (group sessions). |
| Equal baseline characteristics in study arms | Unclear risk | Baseline characteristics not reported by individual study arm. |
| Contamination of control group | Low risk | Cluster‐randomised trial design minimises risk of contamination. |
| Methods | Randomised controlled trial of a counselling intervention to support women to stop smoking in pregnancy. Study conducted in a public hospital AN clinic in Newcastle, Australia, with screening from January 1990 to May 1991. | |
| Participants | Inclusion criteria: Pregnant women attending their first AN clinic appointment who answered yes to 'Are you a smoker?", were less than 26 weeks' gestation, ill or psychologically unwell. Exclusion criteria: Not further specified. Recruitment: 1,909 pregnant women were screened by midwives, 725 smokers (38%). 293/538 (54%) eligible women agreed to participate and were randomised (C = 145, I = 148). Baseline characteristics: Not reported. Progress + coding: None | |
| Interventions | Control: Doctor and midwife both informed women that smoking was an important cause of pregnancy problems and they should stop; Midwife provided a package (sticker, pamphlet on risks of smoking and 2‐page cessation guide), none of which were specifically tailored to pregnant women. (ii) 14‐min video on risk information rebuttal of barriers to quitting, cessation tips and 10‐min standardised information. (iii) Counselling from midwife after the video, using a flip chart, with negotiation of a quit date whenever possible. (iv) Self‐help manual on risks, barriers and cessation plus 4 packets of confectionary gum. (v) Lottery chance (4 prizes) for biochemically validated abstainers at the next visit. (vi) Social support from accompanying adult (partner/friend/other) via support tip sheet, contract and form letter, chart, reminder sticker in the medical record, form‐letter and sticker from 1st visit Midwife mailed within 10 days + 2nd visit and 34 to 36 week visit 5‐min counselling from Midwife and 1‐2 min risk advice from Doctor. Women still smoking at 34‐36 weeks were advised to attend an external cessation course. Main intervention strategy: Counselling (tailored) compared to a less intensive intervention. Intensity: Frequency (C = 2, I = 3); Duration (C = 1, I = 2). Intervention provided by existing staff: Effectiveness study. | |
| Outcomes | Biochemically validated point prevalence abstinence at 34 weeks' gestation (late pregnancy*) and 6‐12 weeks' postpartum*. Preterm births* are reported in attrition and re‐included in both numerator and denominator for this outcome. Program costs and time commitments. Discussion of provider views and implementation issues in associated reference (Walsh 2000). | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer‐generated. |
| Allocation concealment (selection bias) | Low risk | Described as "precoded questionnaires in manila envelopes". |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition 14% due to: Leaving clinic (C = 7, I = 7), miscarriage or termination (C = 10, I = 10), and preterm birth (C = 3, I = 4), leaving 252 included in analysis (C = 125, I = 127). 25% lost to follow‐up and further missing data for some variables including cotinine validation, however those with missing data were treated as continuing smokers in the analysis. |
| Selective reporting (reporting bias) | Unclear risk | Only smoking outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Urinary cotinine (<= 500 mmol/L) was measured and revealed discrepancy with self‐reported smoking status. Biochemically validated with urinary cotinine (I = 86%, C = 78%). Cotinine data inconsistent with self‐report were 52% in controls and 12% in the intervention group. |
| Blinding of participants and personnel (performance bias) | High risk | Educational intervention by UC providers and notes flagged. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | High risk | Midwives involved in recruitment to the trial had variable 'success' in consent rates (9%‐76%). Overall participation was quite low (54%). |
| Equal baseline characteristics in study arms | Low risk | Report states baseline characteristics were equal on 12 variables tested. |
| Contamination of control group | Unclear risk | Same care providers for both groups. |
| Methods | Randomised controlled trial of the dietitian‐led behaviour change 'Healthy start to pregnancy' (HSP) workshop. The study was conducted in a tertiary Maternal Health service in South East Queensland, Australia between 31 August 2010 and 7 March 2011. | |
| Participants | Inclusion criteria: Women > 18 (or < 18 with parental consent) attending their booked visit at the Maternal Health research site Exclusion criteria: Women were excluded if they were unable to read and speak English at a level that allowed completion of pen‐and‐paper survey. Recruitment: 882 approached, 360 randomised (60 smokers), 178 to intervention (29 smokers) and 182 to control (31 smokers) Baseline characteristics: Unable to determine baseline characteristics of smokers as just a small subset of a larger nutritional intervention. | |
| Interventions | Control: Usual nutrition care through the Maternal Health provider. Intervention: A 60‐min 'healthy start to pregnancy', which included a smoking component based on the 5 A's and aimed to influence behaviours with demonstrated health outcomes. Main Intervention strategy: Maternal health intervention with smoking cessation component: Counselling (single) vs UC Intensity: Frequency: (C = 0, I = 2); Duration: (C = 0, I = 3). Progress + coding: None as unable to determine characteristics of subgroup of smokers. | |
| Outcomes | Self‐reported not smoking at 12 weeks*, Intention to breastfeed, diet quality index, weekly mins of physical activity. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | The computerised randomisation process was managed by the research hospitals clinical research support unit. |
| Allocation concealment (selection bias) | Low risk | Group allocation was concealed using sealed opaque envelopes. |
| Incomplete outcome data (attrition bias) | Low risk | ITT analysis was used. |
| Selective reporting (reporting bias) | Low risk | All primary outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | Smoking was not biochemically validated, just self‐report. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Not specified but not practical to blind women and providers to educational intervention. |
| Blinding of outcome assessment (detection bias) | Low risk | All outcomes were self‐report. |
| Incomplete implementation | Unclear risk | Unclear as only a subset of participants were smokers. |
| Equal baseline characteristics in study arms | Unclear risk | Characteristics of smokers can not be determined as part of a broader maternal health intervention. |
| Contamination of control group | Low risk | Intervention was a health promotion workshop which control individuals did not attend. |
| Methods | 3‐armed randomised trial controlled trial (SCRIPT trial I) of interventions to support women to stop smoking in pregnancy. Study conducted in public health clinics in Birmingham, Alabama (USA), from October 1983 to September 1984. | |
| Participants | Inclusion criteria: Pregnant women presenting for their first prenatal visit who reported smoking at least 1 cigarette in the last 7 days. Exclusion criteria: >= 32 weeks' gestation. Recruitment: 460/1838 (25%) pregnant women screened were current smokers. 368/460 (80%) agreed to participate. Unclear exactly how many randomised to each group as attrition not reported by study arm. Baseline characteristics: No baseline data on cigarettes/day. Mean age: 23.6; Black: 57%; Mean years education 11.5. Progress + coding: Low SES as attending public clinics. | |
| Interventions | A: Control: Smoking cessation advice routinely given at prenatal visits: 2‐3 mins within a group prenatal education session at the 1st visit, when maternity clinic staff recommend quitting. Main intervention strategy: Counselling (multiple intervention) compared to UC. Control and Intervention 1 (arm A and B) compared in this study ID, please see Windsor 1985 (AvC) for intervention 2. Intensity: Frequency: (C = 0, I = 1); Duration: (C = 0, I = 1). Intervention provided by dedicated study staff (health educators): Efficacy study. | |
| Outcomes | Biochemically validated point prevalence abstinence at mid‐pregnancy, and during last month of pregnancy or within 48 hours of birth (late pregnancy*), and number of women who self‐reported reduction in smoking in late pregnancy*. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer‐generated. |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition 29/338 (9%) due to: leaving system or moved (9), miscarriage or termination (10), and 10 who went to poorly attended group discussions (this intervention abandoned), leaving 309 included in analysis (C = 104, I1 = 103, I2 = 102). All other women lost to follow‐up were treated as continuing smokers. |
| Selective reporting (reporting bias) | Unclear risk | Only smoking outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation of self‐reported smoking cessation using salivary thiocyanate < 100 ug/mL. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Educational intervention by health educators in AN clinics. Participants unlikely to be blinded. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | "Multiple attempts were made to bring pregnant smokers together for a peer‐led, focused group discussion: not feasible in this setting". |
| Equal baseline characteristics in study arms | Low risk | Characteristics in study arms appear equal. |
| Contamination of control group | Low risk | Administered by trained health educators, not involved in pregnancy care. |
| Methods | 3‐armed randomised trial controlled trial (SCRIPT trial I) of interventions to support women to stop smoking in pregnancy. Study conducted in public health clinics in Birmingham, Alabama (USA), from October 1983 to September 1984. | |
| Participants | Inclusion criteria: Pregnant women presenting for their first prenatal visit who reported smoking at least 1 cigarette in the last 7 days. Exclusion criteria: >= 32 weeks' gestation. Recruitment: 460/1838 (25%) pregnant women screened were current smokers. 368/460 (80%) agreed to participate. Unclear exactly how many randomised to each group as attrition not reported by study arm. Baseline characteristics: No baseline data on cigarettes/day. Mean age: 23.6; Black: 57%; Mean years education 11.5. Progress + coding: Low SES as attending public clinics. | |
| Interventions | A: Control: Smoking cessation advice routinely given at prenatal visits: 2‐3 mins within a group prenatal education session at the 1st visit, when maternity clinic staff recommend quitting. Main intervention strategy: Counselling (multiple intervention) compared to UC. Control and Intervention 2 (arm A and C) compared in this study ID, please see Windsor 1985 (AvB) for intervention 1 Intensity: Frequency: (C = 0, I = 1); Duration: (C = 0, I = 1). Intervention provided by dedicated study staff (health educators): Efficacy study. | |
| Outcomes | Biochemically validated point prevalence abstinence at mid‐pregnancy, and during last month of pregnancy or within 48 hours of birth (late pregnancy*); and number of women who self‐reported reduction in smoking in late pregnancy*. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer‐generated. |
| Allocation concealment (selection bias) | Unclear risk | No information provided. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition 29/338 (9%) due to: leaving system or moved (9), miscarriage or termination (10), and 10 who went to poorly attended group discussions (this intervention abandoned), leaving 309 included in analysis (C = 104, I1 = 103, I2 = 102). All other women lost to follow‐up were treated as continuing smokers. |
| Selective reporting (reporting bias) | Unclear risk | Only smoking outcomes reported. |
| Other bias | Low risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation of self‐reported smoking cessation using salivary thiocyanate < 100 ug/mL. |
| Blinding of participants and personnel (performance bias) | Unclear risk | Educational intervention by health educators in AN clinics. Participants unlikely to be blinded. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Unclear risk | "Multiple attempts were made to bring pregnant smokers together for a peer‐led, focused group discussion: not feasible in this setting". |
| Equal baseline characteristics in study arms | Low risk | Characteristics in study arms appear equal. |
| Contamination of control group | Low risk | Administered by trained health educators, not involved in pregnancy care. |
| Methods | Randomised controlled trial (SCRIPT trial II) of a cognitive behaviour therapy intervention to support women to stop smoking in pregnancy. Study conducted in 4 public maternity clinics of the Jefferson County Health Department in Birmingham, Alabama (USA), with recruitment from September 1987 to November 1989. | |
| Participants | Inclusion criteria: Pregnant women who self‐reported smoking during the first prenatal visit 'at least one puff of one cigarette in the last 7 days'. Exclusion criteria: >= 32 weeks' gestation, did not stay for visit or did not return, prisoners, or had difficulty reading the baseline questionnaire. Recruitment: 1171/4352 (27%) of women screened at first prenatal visit were current smokers and 210 (3%) spontaneous quitters (who were included in a separate trial: Lowe 1997). 994/1061 (94%) eligible women agreed to participate and were randomised (C = 501, I = 493). Baseline characteristics: Mean cotinine 114 ng/mL. 45% had low cotinine levels (< 99 ng/mL). Mean age = 24.6 years; Mean education = 12.4 years; Black = 52%. Progress + coding: Low SES in this review as attending public maternity clinic. | |
| Interventions | Control: 2‐min talk on smoking in 30 min group session at first AN visit in which women were urged to quit and given 2 pamphlets: "Smoking and the two of you'"+ "Where to find help if you want to stop" including the name, contact phone number and cost of their local program. (i) 15‐min standardised cessation skills and risk counselling session from trained female health education counsellor + 7‐day self‐directed cessation guide on how to quit written at 6th Grade level. (ii) Clinic reinforcement (chart sticker) + letter from Doctor within 7 days. (iii) Social support in form of a 'buddy' letter, contract and buddy tip sheet + monthly newsletter with testimonials, cessation tips and additional information on risks. Main intervention strategy: Counselling (multiple intervention) compared to a less intensive intervention. Intensity: Frequency (C = 1, I = 4), Duration: (C = 1, I = 3). Intervention provided by dedicated project staff: Efficacy study. | |
| Outcomes | Biochemically validated point prevalence abstinence at 4‐8 weeks after first visit (midpoint), 32 weeks' gestation (late pregnancy*). "Significant" reduction* if cotinine at least 50% value of baseline cotinine*. Cost estimates. Separate trial reports data on spontaneous quitters (Lowe 1997). | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Computer‐generated. |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Unclear risk | Attrition 180/994 (18%) due withdrawal from the service, miscarriage or abortion (C = 87, I = 93) were not included in analysis, leaving C = 414, I = 400. Further 15% lost to follow‐up survey or cotinine analysis included as continuing smokers in this review. |
| Selective reporting (reporting bias) | Unclear risk | Data on gestation and birthweight were collected but the published analysis is by stopping smoking and the timing of cessation rather than by allocation, so not included in outcome tables. |
| Other bias | Unclear risk | No other bias detected. |
| Biochemical validation of smoking abstinence (detection bias) | Low risk | Biochemical validation of smoking status using salivary cotinine (cut‐off >= 30 ng/mL). |
| Blinding of participants and personnel (performance bias) | High risk | Notes flagged. Educational intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | Process evaluation showed 100% implementation of counselling and social support, and 88% for re‐inforcement at subsequent visits. |
| Equal baseline characteristics in study arms | Low risk | NS difference in baseline cotinine. |
| Contamination of control group | Low risk | Trained counsellor, not pregnancy care provider, delivered the intervention. |
| Methods | Randomised controlled trial (SCRIPT Trial III) of counselling intervention provided by routine care staff (effectiveness study) to support women to stop smoking in pregnancy. Study conducted in 16/67 counties providing Medicaid care in Birmingham, Alabama (USA). Counties matched by number of smokers and percentage Black and White women, and 1 county per dyad (n = 8) randomly selected to participate in study. There were 10 prenatal care clinics and 28 regular staff members in the 8 counties selected. Recruitment dates not reported, but study conducted over 5 years. | |
| Participants | Inclusion criteria: Pregnant women who reported ≥1 cigarette ('even one puff') in the last 7 days, or had a cotinine level ≥20 ng/mL. Exclusion criteria: Not further specified. Recruitment: 6,514 women were screened at first AN visit and 1340/1736 (77%) eligible smokers agreed to participate. 1 trial site dropped out leaving 1093 who were randomised (C = 546, I = 547). Baseline characteristics: Cigarettes per day: C = 9.8 (and 10.3 among dropouts), I = 10.4 (and 12.0 among dropouts); Lives with smoker: C = 69.8 (and 75.3% among dropouts), I = 73.7 (and 66% among dropouts). Mean cotinine: C = 163, I = 181. Mean age: 22 years; Black C = 15.7%, I = 15.4%. Progress + coding: Low SES as Medicaid clinics. | |
| Interventions | Staff orientation and assessment, and 3 hours SCRIPT training for staff in intervention sites. Control: All participants received 4 elements of the "5A's" best practice guidelines (Ask–Advise–Remind). Intervention: Participants received (Assist) Procedures 4 through 8: Main intervention strategy: Counselling (multiple intervention) compared to a less intensive intervention. Intensity: Frequency (C = 2, I =2), Duration (C = 1, I = 2). Intervention provided by existing staff: Effectiveness study. | |
| Outcomes | Biochemically validated point prevalence abstinence in late pregnancy* (> 60 days after first visit, and < 90 days postpartum). Number with a "significant reduction" in cotinine* (> 50ng/mL at baseline and < 50% at follow‐up, quitters not included as significant reducers). An additional 'historical' control group also provides comparison pre and post intervention. | |
| Notes | ||
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Described as 'randomly selected' counties. Then "Smokers were randomly assigned at each clinic to an experimental group or control group after screening, consent, and baseline assessment". |
| Allocation concealment (selection bias) | Unclear risk | Not reported. |
| Incomplete outcome data (attrition bias) | Low risk | Attrition: C = 97/546 (17%) and I = 95/547(17%). Reasons for dropout not reported. An intent‐to‐treat policy was used in the computation of impact rates and all dropouts included as continuing smokers in this review. |
| Selective reporting (reporting bias) | Unclear risk | Unclear if there was 1 or 2 assessments (i.e. 1 assessment between > 60 days after first visit and < 90 days post partum; or 2 'assessments performed > 60 days after first visit, and < 90 days postpartum'). Only 1 assessment reported. |
| Other bias | High risk | Figures in Table 1 (baseline, C = 546, I = 547) conflict with the outcome denominator in Table 2, which is reported to include those lost to follow‐up (C = 549, I = 544). Figures reported in Table 1 used for denominator and Table 2 for numerator in this report. |
| Biochemical validation of smoking abstinence (detection bias) | High risk | 72% self‐reported quitters validated with biochemical verification (salivary cotinine < 20 ng/mL). 10% non‐disclosure of smoking detected. |
| Blinding of participants and personnel (performance bias) | High risk | Participants and personnel not blinded to counselling intervention. |
| Blinding of outcome assessment (detection bias) | Unclear risk | Not reported. |
| Incomplete implementation | Low risk | Process evaluation showed reasonable implementation (over 80%). |
| Equal baseline characteristics in study arms | Unclear risk | Equal on all variables apart from mean cotinine (ng/mL) |
| Contamination of control group | High risk | Process evaluation suggests there was significant contamination of the randomised control group with regular clinic staff providing the intervention to both study arms. |
AFP: alpha fetoprotein
ALA: American Lung Association
AN: antenatal
BP: blood pressure
C: control group
CBASP: Cognitive Behavioral Analysis System of Psychotherapy
CBT: cognitive behavioural therapy
CI: confidence interval
CO: carbon monoxide
ETSE: environmental tobacco smoke exposure
GP: general practitioner
HMO: Health Maintenance Organisation
HW: health and wellness
I: intervention group
ICC: intracluster correlation co‐efficient
IPV: intimate partner violence
ITT: intention‐to‐treat
LBW: low birthweight
MI: motivational interviewing
min(s): minute(s)
MRFIT: randomised trial of health promotion carried out in the US
NCBI: non‐contingent behavioral incentives
NICU: neonatal intensive care unit
NNTB: number needed to treat for an additional beneficial outcome
NRT: nicotine replacement therapy
NS: non‐significant
OPD: out‐patient department
Pls: principal investigators
ppm: parts per million
PPROM: preterm, prelabour rupture of the membranes
RH: Rhesus
SD: standard deviation
SES: socioeconomic status
SHO: senior house officer
TAU: treatment as usual
TFS: teen fresh start
TFSB: teen fresh start + peer support
UC: usual care
UK: United Kingdom
US: ultrasound
USA: United States of America
vs: versus
WIC: Food program for Women, Infants and Children in the USA
Characteristics of excluded studies [ordered by study ID]
| Study | Reason for exclusion |
| Program description only, not a randomised controlled study. | |
| Women included were not‐pregnant, plus quasi‐randomised study design. | |
| Cohort study, not a randomised study design. | |
| Cohort study only, no control or comparison group. | |
| Part of the intervention is provided during pregnancy but primary aim of the study is to prevent relapse after pregnancy and postpartum outcomes only reported. | |
| Quasi‐experimental design. Control and experimental convenience samples collected consecutively. | |
| Retrospective audit only. | |
| Controlled observational study of bupropion for smoking cessation in pregnancy. | |
| Directed at partners of smoking women not pregnant women who smoke. | |
| Randomised controlled trial of pharmacological intervention with equal psychosocial support in both arms. | |
| Controlled trial/evaluation of "The Community‐Based Family Resource and Support" (CBFRS) Program. Control group not randomised. | |
| Quasi‐cluster‐randomised study with inadequate sequence generation (40 practices selected with matched controls). | |
| Non‐randomised postpartum intervention to promote smoking cessation and breastfeeding. | |
| Longitudinal cohort study only. | |
| Evaluation of 'SMART moms' project, which has no control group. | |
| Randomised‐controlled trial of pharmacological interventions (nicotine replacement therapy) with equal psychosocial support in both study arms. | |
| Controlled trial/evaluation of the "Healthy Baby Second Hand Smoke Study" uses historical controls. Good documentation of implementation problems. | |
| The intervention took place in 1 HMO clinic with historical controls from the same clinic and concurrent controls from a second clinic. There was no randomisation of clinics and no adjustment of the data for clustering. | |
| Evaluation of smoking cessation counselling using a historical control group only (pre‐post study design, not randomised and no contemporary control group). | |
| Pregnant women excluded from this study (non‐pregnant study population). | |
| Pre‐test post‐test control group design (not randomised). | |
| Intervention aimed at partners of pregnant women only. Pregnant women not included in the intervention. | |
| Controlled clinical trial of postpartum relapse prevention. Excluded as not a trial during pregnancy, and not randomised. | |
| Evaluation of 'The BABY and ME‐Tobacco Free' program for relapse prevention postpartum. Quasi‐experimental design with non‐randomised control group (matched randomly selected controls). | |
| Study of effect of one 15‐minute counselling session and a follow‐up telephone call, performed 1994‐95, using historical controls from 1993‐1994. | |
| In this controlled clinical trial the intervention was carried out in 1 hospital with another hospital in the same city acting as a control, after a prior descriptive study which showed the similarity between the 2 in terms of social and demographic factors including smoking. There was no randomisation and recruitment differed substantially across the 2 sites. Data for smoking reduction and smoking cessation are combined in the paper with no separate data on cessation and no adjustment for clustering. | |
| Cohort study design. | |
| Controlled trial with a volunteer sample of non‐pregnant contest registrants, compared with a randomly selected group of smokers not exposed to the campaign/contest. Context registrants not randomised and there is evidence of differences between groups. | |
| Counselling intervention aimed at relapse prevention postpartum only. Screened for participation during birth admission. | |
| Consecutive recruitment. | |
| Intervention to reduce 'Environmental Tobacco Smoke' exposure aimed at postpartum relapse prevention only. | |
| Pilot study with 37/53 participants consecutively assigned (not randomised). | |
| Randomised controlled trial of pharmacotherapy (nicotine replacement therapy) with equal psychosocial support in both study arms. | |
| Assignment by alternate odd/even dates. | |
| Postpartum trial only which measures paediatrician implementation of smoking cessation and relapse prevention interventions. | |
| Controlled study, not randomised, of effects of a population‐based smoking cessation program and its impact on smoking in pregnancy. Controls were matched on inclusion criteria from another district. | |
| Postpartum intervention. | |
| Cohort smoking data from a randomised controlled trial of maternal vaccines. | |
| Non‐pregnant population. | |
| Randomised controlled trial of pharmacotherapy with equal psychosocial support in both study arms. | |
| Evaluation of a motivational interviewing intervention with no control group. | |
| Intervention aimed at partners of pregnant women only to reduce passive tobacco smoke exposure for pregnant women in Iran. | |
| Unable to determine number allocated to each trial arm and unclear what happened if unequal flip of coin. | |
| Prenatal classes, rather than individual women, were randomly allocated to provide the intervention or not. The intervention was provided in late pregnancy with no outcome data collected during pregnancy but only data 4 months after birth. There was no adjustment for cluster‐randomisation in the analysis of the study findings. | |
| Intervention aimed at partners of pregnant women only to reduce passive tobacco smoke exposure for pregnant women in China. | |
| Intervention is for postpartum women. | |
| Intervention aimed at smoking cessation in men (partners of pregnant women). | |
| Quasi‐randomised study with inadequate sequence generation (allocation by alternate clinic weeks). | |
| Quasi‐randomised study with inadequate sequence generation (allocation by alternate clinic weeks). | |
| Quasi‐randomised study with inadequate sequence generation (allocation by date of clinic visit). | |
| A pilot study of a pharmacological intervention (bupropion). | |
| Study designed to promote postpartum smoking cessation (not antepartum or part of a trial conducted in pregnancy). | |
| Intervention to promote smoking cessation among a general (not specifically pregnant) primary care population. | |
| Double‐blind study of nicotine replacement therapy. | |
| Randomised controlled trial of pharmacotherapy with equal psychosocial support in both study arms. | |
| Quasi‐randomised study with inadequate sequence generation (alternate allocation according to day of week). | |
| Randomised controlled trial of pharmacotherapy (nicotine replacement therapy) with equal psychosocial support in both arms. | |
| Quasi‐randomised study with sequential allocation to study arms. | |
| Intervention aimed at postpartum relapse prevention only. Mother's were recruited during infant's admission to NICU. | |
| Observational cohort study only with no comparison group. | |
| Randomised controlled trial of pharmacotherapy (nicotine replacement therapy) and equal psychosocial support in both arms. | |
| Intervention aimed at partners of women who smoke. | |
| The intervention in this trial was unusual in that the focus was on anticipated benefits of smoking cessation to women themselves (not on harm to the fetus and infant), and on alternative coping strategies, with a designated midwife‐facilitator to answer queries and provide friendly advice and encouragement. The intervention was carried out in 1 hospital with another being a comparison setting, after a prior study which showed the similarity between the 2 in social and demographic factors including smoking rates. There was no randomisation. Recruitment differed significantly across the 2 hospitals. Data for smoking cessation and smoking reduction are combined with no separate data on cessation and no adjustment for clustering. | |
| Postpartum intervention only. No interventions in pregnancy. | |
| Intervention aimed at postpartum relapse prevention only. | |
| Quasi‐experimental study with inadequate sequence generation (group allocation by alternate weeks). | |
| This controlled clinical trial of the impact of using interactive software to promote smoking cessation, was excluded as it used historical controls. | |
| Not a smoking in pregnancy intervention. | |
| Not a randomised controlled trial. | |
| Intervention aimed at partner's of pregnant women only. Aim was to maximise potential of life‐changing period for men too. Did not include pregnant women. | |
| Randomised trial of relapse prevention counselling in the postpartum period only (not pregnancy). | |
| Intervention of tailored smoking cessation letters, self‐help materials and counselling for the general population (not specifically pregnant women). | |
| This prospective controlled clinical trial design to test the effect of a low intensity intervention, used historical controls. | |
| Quasi‐experimental study with inadequate sequence generation (3 months consecutive recruitment for each arm). | |
| Preconceptual intervention and unable to determine how many participants were pregnant. | |
| General study population (not pregnant). Implementation trial to change provider behaviour and increase referrals to quitline. Estimated smoking cessation outcome data only. | |
| Not pregnant women. | |
| Cluster‐randomised controlled trial comparing 2 postnatal interventions to improve maternal health. | |
| Quasi‐experimental design with a non‐randomised controlled pre‐post test study design. | |
| Quasi‐experimental study with inadequate sequence generation (80% control group not randomly assigned). | |
| Intervention aimed at postpartum relapse prevention only with women recruited during birth admission. | |
| This randomised study of the effect of midwifery training on smoking cessation intervention implementation and pregnancy outcomes, was excluded due to concerns about allocation concealment (clinic day allocation). | |
| Randomised controlled trial of a pharmacological intervention (nicotine replacement therapy) and equal psychosocial support in both study arms. | |
| Postnatal intervention in pediatric setting. |
HMO: Health Maintenance Organisation
NICU: neonatal intensive care unit
Characteristics of ongoing studies [ordered by study ID]
| Trial name or title | Quit Smoking Now (with contingency management). |
| Methods | Randomised controlled trial (2 arms). |
| Participants | Pregnant women attending prenatal care at Jackson Health System, Miami‐Dade, Florida. |
| Interventions | Women will receive standard of care Quit Smoking Now tobacco education and support plus prize‐based contingency management. |
| Outcomes | Their smoking status will be monitored from quit date through 3 months postpartum via carbon monoxide and salivary cotinine levels. |
| Starting date | October 2015‐August 2017. |
| Contact information | Veronica H Accornero, [email protected] |
| Notes |
| Trial name or title | Not stated. |
| Methods | Cluster‐randomised controlled trial. |
| Participants | Pregnant women attending antenatal care in Argentina and Uruguay. |
| Interventions | A multifaceted intervention to implement the “5A’s” strategy. |
| Outcomes | Provision of smoking advice and smoking abstinence. |
| Starting date | Not stated. |
| Contact information | F Althabe: Department of Mother and Child Health Research, Institute for Clinical Effectiveness and Health Policy (IECS), Buenos Aires, Argentina. |
| Notes | Email sent to author 11/11/15, study started in 2011 and notes completion as August 2014. Published by time of this review submission (10/12/2016) but not included in this update. |
| Trial name or title | Not stated. |
| Methods | Randomised clinical trial. |
| Participants | Pregnant women smoking at least 1 cigarette each day attending 4 clinics in Madrid, Spain. |
| Interventions | Brief counselling (3 to 5 minutes) on smoking cessation compared with a group intervention over 3 half‐hour sessions. |
| Outcomes | Not clear. |
| Starting date | Not clear. |
| Contact information | [email protected] No response from authors to written request for further trial information on 18/7/2012. |
| Notes | Original article in Spanish. Email sent to author 11/11/15, no response. Study report (2004) describes the study design. No papers including results have yet been identified. |
| Trial name or title | The Mommy check‐up study. |
| Methods | Randomised controlled trial. |
| Participants | Pregnant women aged 18‐45 in Michigan, USA who attended. |
| Interventions | SmokeFreeMom is a mobile text messaging service designed for pregnant women across the USA to help them quit smoking. |
| Outcomes | Abstinence from smoking, 7‐day point‐prevalence. |
| Starting date | January 2015‐April 2015. |
| Contact information | Elena Bronshtein, [email protected] |
| Notes | Emailed 11/11/2015, replied 11/11/15 and advised that the study is completed and will provide outcomes when available. |
| Trial name or title | Mi‐Quit. |
| Methods | Randomised controlled trial. |
| Participants | Pregnant women recruited from hospital antenatal clinics in England. |
| Interventions | MiQuit is an automated responsive text message support programme lasting 12 weeks, which provides tailored smoking cessation support and advice to the participant’s mobile phone. |
| Outcomes | No primary outcome as this is a feasibility study. |
| Starting date | February 2014. |
| Contact information | Sue Cooper, [email protected] |
| Notes | Started recruitment Feb 2014, emailed 11/11/15, replied; all data collected, trying to get published by May. |
| Trial name or title | Not stated. |
| Methods | Ongoing study of intervention to promote smoking cessation among men and women during pregnancy. |
| Participants | Pregnant women and their partners. |
| Interventions | Not clear. |
| Outcomes | Not clear. |
| Starting date | Not clear. |
| Contact information | [email protected] Minimal study information provided in response to email request sent 18/7/2012. |
| Notes | Email sent to author 11/11/15, no response. |
| Trial name or title | Not clear. |
| Methods | Randomised controlled trial. |
| Participants | Pregnant smokers recruited from their antenatal clinics. |
| Interventions | Each mother allocated to the intervention group receives between 4 and 6 visits by the smoking cessation advisor. |
| Outcomes | No outcomes as a protocol paper. |
| Starting date | Not clear. |
| Contact information | No author contact details, BMJ contacted. |
| Notes |
| Trial name or title | Financial incentives for smoking cessation among disadvantaged pregnant women. |
| Methods | Randomised controlled clinical trial. |
| Participants | Pregnant women. |
| Interventions | Financial incentives provided contingent on biochemically confirmed smoking abstinence. |
| Outcomes | 7‐day point prevalence abstinence levels at final antepartum assessment; collected at approximately 28 weeks' gestation. |
| Starting date | January 2014‐May 2018. |
| Contact information | Mary Ellen Lynch, [email protected] |
| Notes |
| Trial name or title | Reducing ETS exposure of pregnant women and newborns. |
| Methods | Randomised 2‐arm study in 6 prenatal clinics designed to develop and evaluate the efficacy of 5 tailored DVDs in reducing exposure to ETS among low‐income pregnant/postpartum women. |
| Participants | Pregnant women who attend first prenatal visit by 16 weeks' gestation who are exposed to tobacco smoke daily. Exclusion criteria: women expecting complications or multiple births. |
| Interventions | Provision of tailored DVDs to take home. |
| Outcomes | Salivary cotinine concentration of mother and baby. |
| Starting date | Feb 2006. |
| Contact information | Thomas M Lasater, Brown University, Rhode Island. email: [email protected] |
| Notes | Started in Feb 2006 and estimated completion date Feb 2009. Email sent to author 11/11/2015. |
| Trial name or title | RCT protocol of varying financial incentive amounts for smoking cessation among pregnant women. |
| Methods | RCT (pilot). |
| Participants | 90 consenting pregnant women. |
| Interventions | 2 intervention arms will be assessed: (1) a $AUD20 incremental personal financial incentive; and (2) a $AUD40 incremental personal financial incentive. |
| Outcomes | (i) consent rates; (ii) loss to follow‐up rates of study participants and (iii) participant compliance with saliva and hair cotinine analyses for biochemical validation of smoking status. Womens perceptions of the intervention will also be ascertained by 6 interview questions. |
| Starting date | Not clear. |
| Contact information | |
| Notes | Email sent to author 11/11/2015 Received magazine article with some results 17/11/2015. Australian New Zealand Clinical Trials Registry (ANZCTR) number: ACTRN12612000399897. |
| Trial name or title | Community intervention to reduce tobacco use among Alaskan pregnant women. |
| Methods | Randomised controlled cluster clinical trial. |
| Participants | Pregnant Alaska native women over the age of 18 years who are < 26 weeks' gestation and have access to a working telephone. |
| Interventions | A novel, multi‐component, theory‐based intervention for reducing tobacco use during pregnancy, incorporating both individually targeted and community level components delivered by female elders "Native Sisters. |
| Outcomes | Tobacco use status, biochemically verified tobacco use, changes from baseline in self‐efficacy for non‐tobacco use scores. |
| Starting date | May 2014‐April 2018. |
| Contact information | Christi A Patten, [email protected] |
| Notes |
| Trial name or title | Not stated. |
| Methods | Randomised controlled trial. |
| Participants | 302 low‐income pregnant women less than 28 weeks pregnant, English or Spanish‐speaking, and who were not receiving inpatient drug treatment were recruited from multiple obstetric sites in the Boston metropolitan area (USA). Current smokers or women smoking in the past 3 months (recent quitters) were included. |
| Interventions | Motivational interviewing interventions to promote smoking cessation and reduce ETS exposure provided during 3 home visits, with feedback provided about the household nicotine levels. |
| Outcomes | Smoking cessation at end of pregnancy and relapse prevention; infant health outcomes; life‐years and quality of life; primary cost data and economic analysis. |
| Starting date | 1997‐2000. |
| Contact information | |
| Notes | Email sent to author 11/11/15, no response. |
| Trial name or title | Telephone intervention (California Smokers' Helpline) or pregnant smokers. |
| Methods | Randomised trial. |
| Participants | Pregnant smokers who called the helpline for services. |
| Interventions | Control group received a self‐help quit kit of written materials, including the American Cancer Society booklet for pregnant smokers. Intervention group received the quit kit plus up to 7 counselling calls. |
| Outcomes | Self‐reported smoking cessation in third trimester. |
| Starting date | |
| Contact information | Shu‐Hong Zhu 2004, University of California. [email protected] |
| Notes | Email sent to author 11/11/2015 and received reply 'The paper is under review and we should hear from the editor in a few weeks'. |
ETS: environmental tobacco smoke
PFI: Personal Financial Incentive
RCT: randomised controlled trial
Data and analyses
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 30 | 12432 | Risk Ratio (M‐H, Random, 95% CI) | 1.44 [1.19, 1.73] |
| Analysis 1.1  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 13 | 4565 | Risk Ratio (M‐H, Random, 95% CI) | 1.33 [1.01, 1.74] |
| 1.2 Multiple interventions | 11 | 4048 | Risk Ratio (M‐H, Random, 95% CI) | 1.42 [1.04, 1.93] |
| 1.3 Tailored interventions | 6 | 3819 | Risk Ratio (M‐H, Random, 95% CI) | 1.49 [1.01, 2.20] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 21 | 9703 | Risk Ratio (M‐H, Random, 95% CI) | 1.23 [1.04, 1.45] |
| Analysis 1.2  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Single interventions | 9 | 3903 | Risk Ratio (M‐H, Random, 95% CI) | 1.12 [0.90, 1.41] |
| 2.2 Multiple interventions | 8 | 3823 | Risk Ratio (M‐H, Random, 95% CI) | 1.26 [0.92, 1.73] |
| 2.3 Tailored interventions | 4 | 1977 | Risk Ratio (M‐H, Random, 95% CI) | 1.42 [0.84, 2.41] |
| 3 Continued abstinence (relapse prevention) in late pregnancy for spontaneous quitters Show forest plot | 8 | 688 | Risk Ratio (M‐H, Random, 95% CI) | 1.06 [0.93, 1.21] |
| Analysis 1.3  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 3 Continued abstinence (relapse prevention) in late pregnancy for spontaneous quitters. | ||||
| 3.1 Single interventions | 2 | 100 | Risk Ratio (M‐H, Random, 95% CI) | 1.00 [0.93, 1.07] |
| 3.2 Multiple interventions | 3 | 297 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.93, 1.26] |
| 3.3 Tailored interventions | 3 | 291 | Risk Ratio (M‐H, Random, 95% CI) | 1.19 [0.97, 1.46] |
| 4 Abstinence at 0 to 5 months postpartum Show forest plot | 11 | 2926 | Risk Ratio (M‐H, Random, 95% CI) | 1.59 [1.26, 2.01] |
| Analysis 1.4  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 4 Abstinence at 0 to 5 months postpartum. | ||||
| 4.1 Single interventions | 7 | 1924 | Risk Ratio (M‐H, Random, 95% CI) | 1.58 [1.21, 2.06] |
| 4.2 Multiple interventions | 3 | 635 | Risk Ratio (M‐H, Random, 95% CI) | 2.55 [1.17, 5.53] |
| 4.3 Tailored interventions | 1 | 367 | Risk Ratio (M‐H, Random, 95% CI) | 1.18 [0.62, 2.25] |
| 5 Abstinence at 6 to 11 months postpartum Show forest plot | 6 | 2458 | Risk Ratio (M‐H, Random, 95% CI) | 1.33 [1.00, 1.77] |
| Analysis 1.5  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 5 Abstinence at 6 to 11 months postpartum. | ||||
| 5.1 Single interventions | 3 | 1098 | Risk Ratio (M‐H, Random, 95% CI) | 1.36 [0.99, 1.86] |
| 5.2 Multiple interventions | 2 | 733 | Risk Ratio (M‐H, Random, 95% CI) | 1.69 [0.48, 5.96] |
| 5.3 Tailored interventions | 1 | 627 | Risk Ratio (M‐H, Random, 95% CI) | 0.99 [0.40, 2.46] |
| 6 Abstinence at 12 to 17 months postpartum Show forest plot | 2 | 431 | Risk Ratio (M‐H, Random, 95% CI) | 2.20 [1.23, 3.96] |
| Analysis 1.6  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 6 Abstinence at 12 to 17 months postpartum. | ||||
| 6.1 Single interventions | 2 | 431 | Risk Ratio (M‐H, Random, 95% CI) | 2.20 [1.23, 3.96] |
| 7 Abstinence at 18+ months postpartum Show forest plot | 3 | 798 | Risk Ratio (M‐H, Random, 95% CI) | 0.98 [0.50, 1.92] |
| Analysis 1.7  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 7 Abstinence at 18+ months postpartum. | ||||
| 7.1 Single interventions | 1 | 239 | Risk Ratio (M‐H, Random, 95% CI) | 1.17 [0.31, 4.42] |
| 7.2 Multiple interventions | 2 | 559 | Risk Ratio (M‐H, Random, 95% CI) | 0.92 [0.43, 2.00] |
| 8 Reduction in late pregnancy: biochemically validated Show forest plot | 2 | 1002 | Risk Ratio (M‐H, Random, 95% CI) | 0.79 [0.49, 1.28] |
| Analysis 1.8  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 8 Reduction in late pregnancy: biochemically validated. | ||||
| 8.1 Single interventions | 1 | 756 | Risk Ratio (M‐H, Random, 95% CI) | 0.63 [0.34, 1.20] |
| 8.2 Multiple interventions | 1 | 246 | Risk Ratio (M‐H, Random, 95% CI) | 1.04 [0.51, 2.13] |
| 9 Reduction in late pregnancy: self reported (various definitions) Show forest plot | 5 | 839 | Risk Ratio (M‐H, Random, 95% CI) | 1.66 [1.27, 2.17] |
| Analysis 1.9  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 9 Reduction in late pregnancy: self reported (various definitions). | ||||
| 9.1 Single interventions | 2 | 323 | Risk Ratio (M‐H, Random, 95% CI) | 1.61 [1.06, 2.43] |
| 9.2 Multiple interventions | 3 | 516 | Risk Ratio (M‐H, Random, 95% CI) | 1.74 [1.17, 2.57] |
| 10 Biochemical measures in late pregnancy: mean cotinine Show forest plot | 6 | 1884 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.44 [‐0.76, ‐0.12] |
| Analysis 1.10  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 10 Biochemical measures in late pregnancy: mean cotinine. | ||||
| 10.1 Single interventions | 4 | 1443 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.35 [‐0.69, ‐0.02] |
| 10.2 Multiple interventions | 2 | 441 | Std. Mean Difference (IV, Random, 95% CI) | ‐1.20 [‐3.64, 1.24] |
| 11 Mean cigarettes per day in late pregnancy Show forest plot | 11 | Std. Mean Difference (IV, Random, 95% CI) | Totals not selected | |
| Analysis 1.11  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 11 Mean cigarettes per day in late pregnancy. | ||||
| 11.1 Single interventions | 7 | Std. Mean Difference (IV, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 11.2 Multiple interventions | 2 | Std. Mean Difference (IV, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 11.3 Tailored interventions | 2 | Std. Mean Difference (IV, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 12 NICU admissions Show forest plot | 2 | 1140 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.52, 1.29] |
| Analysis 1.12  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 12 NICU admissions. | ||||
| 12.1 Single interventions | 1 | 762 | Risk Ratio (M‐H, Random, 95% CI) | 0.71 [0.47, 1.07] |
| 12.2 Tailored interventions | 1 | 378 | Risk Ratio (M‐H, Random, 95% CI) | 1.17 [0.55, 2.46] |
| 13 Very low birthweight infants (< 1500 g) Show forest plot | 2 | 1666 | Risk Ratio (M‐H, Random, 95% CI) | 1.27 [0.60, 2.71] |
| Analysis 1.13  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 13 Very low birthweight infants (< 1500 g). | ||||
| 13.1 Single interventions | 1 | 731 | Risk Ratio (M‐H, Random, 95% CI) | 0.91 [0.32, 2.59] |
| 13.2 Tailored interventions | 1 | 935 | Risk Ratio (M‐H, Random, 95% CI) | 1.83 [0.62, 5.43] |
| 14 Preterm births Show forest plot | 5 | 2653 | Risk Ratio (M‐H, Random, 95% CI) | 0.90 [0.64, 1.27] |
| Analysis 1.14  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 14 Preterm births. | ||||
| 14.1 Single interventions | 3 | 1571 | Risk Ratio (M‐H, Random, 95% CI) | 0.83 [0.60, 1.17] |
| 14.2 Tailored interventions | 2 | 1082 | Risk Ratio (M‐H, Random, 95% CI) | 1.13 [0.46, 2.80] |
| 15 Mean birthweight Show forest plot | 11 | 4925 | Mean Difference (IV, Random, 95% CI) | 40.27 [7.87, 72.66] |
| Analysis 1.15  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 15 Mean birthweight. | ||||
| 15.1 Single interventions | 6 | 1995 | Mean Difference (IV, Random, 95% CI) | 52.87 [‐0.41, 106.15] |
| 15.2 Multiple interventions | 2 | 588 | Mean Difference (IV, Random, 95% CI) | 72.91 [‐89.12, 234.95] |
| 15.3 Tailored interventions | 3 | 2342 | Mean Difference (IV, Random, 95% CI) | 23.25 [‐52.12, 98.62] |
| 16 Perinatal deaths Show forest plot | 2 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 1.16  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 16 Perinatal deaths. | ||||
| 16.1 Single interventions | 1 | 130 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] |
| 16.2 Tailored interventions | 1 | 935 | Risk Ratio (M‐H, Random, 95% CI) | 1.10 [0.52, 2.31] |
| 17 Stillbirths Show forest plot | 4 | 2212 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.51, 2.30] |
| Analysis 1.17  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 17 Stillbirths. | ||||
| 17.1 Single interventions | 2 | 859 | Risk Ratio (M‐H, Random, 95% CI) | 2.58 [0.38, 17.48] |
| 17.2 Tailored interventions | 2 | 1353 | Risk Ratio (M‐H, Random, 95% CI) | 0.92 [0.41, 2.10] |
| 18 Neonatal deaths Show forest plot | 3 | 2095 | Risk Ratio (M‐H, Random, 95% CI) | 2.06 [0.61, 6.92] |
| Analysis 1.18  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 18 Neonatal deaths. | ||||
| 18.1 Single interventions | 1 | 762 | Risk Ratio (M‐H, Random, 95% CI) | 1.17 [0.07, 18.65] |
| 18.2 Tailored interventions | 2 | 1333 | Risk Ratio (M‐H, Random, 95% CI) | 2.35 [0.61, 9.07] |
| 19 Low birthweight infants (< 2500 g) Show forest plot | 6 | 3836 | Risk Ratio (M‐H, Random, 95% CI) | 0.87 [0.70, 1.08] |
| Analysis 1.19  Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 19 Low birthweight infants (< 2500 g). | ||||
| 19.1 Single interventions | 2 | 1460 | Risk Ratio (M‐H, Random, 95% CI) | 0.79 [0.56, 1.11] |
| 19.2 Multiple interventions | 1 | 414 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.45, 2.61] |
| 19.3 Tailored interventions | 3 | 1962 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.66, 1.32] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 18 | 5657 | Risk Ratio (M‐H, Random, 95% CI) | 1.25 [1.07, 1.47] |
| Analysis 2.1  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 7 | 1145 | Risk Ratio (M‐H, Random, 95% CI) | 1.21 [0.82, 1.80] |
| 1.2 Multiple interventions | 10 | 4260 | Risk Ratio (M‐H, Random, 95% CI) | 1.24 [1.07, 1.44] |
| 1.3 Tailored interventions | 1 | 252 | Risk Ratio (M‐H, Random, 95% CI) | 2.39 [1.03, 5.56] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 15 | 4919 | Risk Ratio (M‐H, Random, 95% CI) | 1.31 [1.10, 1.56] |
| Analysis 2.2  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Single interventions | 6 | 967 | Risk Ratio (M‐H, Random, 95% CI) | 1.37 [0.89, 2.12] |
| 2.2 Multiple interventions | 8 | 3700 | Risk Ratio (M‐H, Random, 95% CI) | 1.25 [1.06, 1.47] |
| 2.3 Tailored interventions | 1 | 252 | Risk Ratio (M‐H, Random, 95% CI) | 2.39 [1.03, 5.56] |
| 3 Continued abstinence (relapse prevention) in late pregnancy (spontaneous quitters) Show forest plot | 5 | 904 | Risk Ratio (M‐H, Random, 95% CI) | 1.06 [0.99, 1.13] |
| Analysis 2.3  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 3 Continued abstinence (relapse prevention) in late pregnancy (spontaneous quitters). | ||||
| 3.1 Single interventions | 3 | 416 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.96, 1.15] |
| 3.2 Multiple interventions | 2 | 488 | Risk Ratio (M‐H, Random, 95% CI) | 1.06 [0.96, 1.17] |
| 4 Abstinence at 0 to 5 months postpartum Show forest plot | 8 | 2647 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.93, 1.43] |
| Analysis 2.4  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 4 Abstinence at 0 to 5 months postpartum. | ||||
| 4.1 Single interventions | 3 | 749 | Risk Ratio (M‐H, Random, 95% CI) | 1.07 [0.81, 1.42] |
| 4.2 Multiple interventions | 4 | 1646 | Risk Ratio (M‐H, Random, 95% CI) | 1.19 [0.99, 1.43] |
| 4.3 Tailored interventions | 1 | 252 | Risk Ratio (M‐H, Random, 95% CI) | 12.80 [1.70, 96.35] |
| 5 Abstinence at 6 to 11 months postpartum Show forest plot | 4 | 1661 | Risk Ratio (M‐H, Random, 95% CI) | 1.09 [0.91, 1.31] |
| Analysis 2.5  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 5 Abstinence at 6 to 11 months postpartum. | ||||
| 5.1 Single interventions | 2 | 495 | Risk Ratio (M‐H, Random, 95% CI) | 1.14 [0.84, 1.54] |
| 5.2 Multiple interventions | 2 | 1166 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.80, 1.38] |
| 6 Abstinence at 12 to 17 months postpartum Show forest plot | 3 | 1578 | Risk Ratio (M‐H, Random, 95% CI) | 1.11 [0.87, 1.41] |
| Analysis 2.6  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 6 Abstinence at 12 to 17 months postpartum. | ||||
| 6.1 Single interventions | 1 | 390 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.76, 1.52] |
| 6.2 Multiple interventions | 2 | 1188 | Risk Ratio (M‐H, Random, 95% CI) | 1.25 [0.71, 2.20] |
| 7 Reduction in late pregnancy: biochemically validated Show forest plot | 2 | 857 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [0.98, 1.87] |
| Analysis 2.7  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 7 Reduction in late pregnancy: biochemically validated. | ||||
| 7.1 Multiple interventions | 2 | 857 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [0.98, 1.87] |
| 8 Reduction in late pregnancy: self‐reported > 50% Show forest plot | 2 | 1235 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [1.07, 1.71] |
| Analysis 2.8  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 8 Reduction in late pregnancy: self‐reported > 50%. | ||||
| 8.1 Multiple interventions | 2 | 1235 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [1.07, 1.71] |
| 9 Mean cigarettes per day in late pregnancy Show forest plot | 2 | 397 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.11 [‐0.30, 0.09] |
| Analysis 2.9  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 9 Mean cigarettes per day in late pregnancy. | ||||
| 9.1 Single interventions | 1 | 121 | Std. Mean Difference (IV, Random, 95% CI) | 0.01 [‐0.34, 0.37] |
| 9.2 Multiple interventions | 1 | 276 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.16 [‐0.40, 0.08] |
| 10 Low birthweight infants (< 2500 g) Show forest plot | 2 | 503 | Risk Ratio (M‐H, Random, 95% CI) | 0.58 [0.32, 1.04] |
| Analysis 2.10  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 10 Low birthweight infants (< 2500 g). | ||||
| 10.1 Single interventions | 1 | 227 | Risk Ratio (M‐H, Random, 95% CI) | 0.55 [0.25, 1.21] |
| 10.2 Multiple interventions | 1 | 276 | Risk Ratio (M‐H, Random, 95% CI) | 0.61 [0.25, 1.50] |
| 11 Preterm births Show forest plot | 3 | 794 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.47, 1.42] |
| Analysis 2.11  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 11 Preterm births. | ||||
| 11.1 Single interventions | 1 | 227 | Risk Ratio (M‐H, Random, 95% CI) | 0.55 [0.25, 1.21] |
| 11.2 Multiple interventions | 1 | 308 | Risk Ratio (M‐H, Random, 95% CI) | 1.17 [0.46, 2.95] |
| 11.3 Tailored interventions | 1 | 259 | Risk Ratio (M‐H, Random, 95% CI) | 1.30 [0.30, 5.71] |
| 12 Mean birthweight Show forest plot | 3 | 546 | Mean Difference (IV, Random, 95% CI) | 56.02 [‐31.46, 143.50] |
| Analysis 2.12  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 12 Mean birthweight. | ||||
| 12.1 Single interventions | 1 | 227 | Mean Difference (IV, Random, 95% CI) | 57.00 [‐93.50, 207.50] |
| 12.2 Multiple interventions | 2 | 319 | Mean Difference (IV, Random, 95% CI) | 76.01 [‐88.59, 240.61] |
| 13 Stillbirths Show forest plot | 1 | 242 | Risk Ratio (M‐H, Random, 95% CI) | 1.84 [0.17, 20.04] |
| Analysis 2.13  Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 13 Stillbirths. | ||||
| 13.1 Single interventions | 1 | 242 | Risk Ratio (M‐H, Random, 95% CI) | 1.84 [0.17, 20.04] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.86, 1.53] |
| Analysis 3.1  Comparison 3 Smoking cessation interventions: counselling vs alternative intervention, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.86, 1.53] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.86, 1.53] |
| Analysis 3.2  Comparison 3 Smoking cessation interventions: counselling vs alternative intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Single interventions | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.86, 1.53] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.63, 1.76] |
| Analysis 3.3  Comparison 3 Smoking cessation interventions: counselling vs alternative intervention, Outcome 3 Abstinence at 0 to 5 months postpartum. | ||||
| 3.1 Single interventions | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.63, 1.76] |
| 4 Abstinence at 6 to 11 months postpartum Show forest plot | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 0.76 [0.33, 1.73] |
| Analysis 3.4  Comparison 3 Smoking cessation interventions: counselling vs alternative intervention, Outcome 4 Abstinence at 6 to 11 months postpartum. | ||||
| 4.1 Single interventions | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 0.76 [0.33, 1.73] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 5 | 629 | Risk Ratio (M‐H, Random, 95% CI) | 1.59 [0.99, 2.55] |
| Analysis 4.1  Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 4 | 484 | Risk Ratio (M‐H, Random, 95% CI) | 1.53 [0.93, 2.49] |
| 1.2 Multiple interventions | 1 | 145 | Risk Ratio (M‐H, Random, 95% CI) | 4.06 [0.46, 35.41] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 3 | 337 | Risk Ratio (M‐H, Random, 95% CI) | 1.45 [0.82, 2.58] |
| Analysis 4.2  Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Single interventions | 3 | 337 | Risk Ratio (M‐H, Random, 95% CI) | 1.45 [0.82, 2.58] |
| 3 Continued abstinence (Relapse prevention) in late pregnancy for spontaneous quitters Show forest plot | 1 | 70 | Risk Ratio (M‐H, Random, 95% CI) | 1.02 [0.86, 1.23] |
| Analysis 4.3  Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 3 Continued abstinence (Relapse prevention) in late pregnancy for spontaneous quitters. | ||||
| 3.1 Single interventions | 1 | 70 | Risk Ratio (M‐H, Random, 95% CI) | 1.02 [0.86, 1.23] |
| 4 Abstinence at 0 to 5 months postpartum Show forest plot | 2 | 237 | Risk Ratio (M‐H, Random, 95% CI) | 3.56 [1.31, 9.67] |
| Analysis 4.4  Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 4 Abstinence at 0 to 5 months postpartum. | ||||
| 4.1 Single interventions | 2 | 237 | Risk Ratio (M‐H, Random, 95% CI) | 3.56 [1.31, 9.67] |
| 5 Mean cigarettes per day in late pregnancy Show forest plot | 2 | 687 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.55 [‐0.94, ‐0.15] |
| Analysis 4.5  Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 5 Mean cigarettes per day in late pregnancy. | ||||
| 5.1 Single interventions | 1 | 552 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.72 [‐0.89, ‐0.55] |
| 5.2 Multiple interventions | 1 | 135 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.32 [‐0.66, 0.02] |
| 6 Low birth weight Show forest plot | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 1.10 [0.66, 1.84] |
| Analysis 4.6  Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 6 Low birth weight. | ||||
| 6.1 Single interventions | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 1.10 [0.66, 1.84] |
| 7 Preterm births (< 37 weeks) Show forest plot | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 1.03 [0.53, 2.00] |
| Analysis 4.7  Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 7 Preterm births (< 37 weeks). | ||||
| 7.1 Single interventions | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 1.03 [0.53, 2.00] |
| 8 Mean birthweight Show forest plot | 1 | 552 | Mean Difference (IV, Fixed, 95% CI) | ‐12.0 [‐102.29, 78.29] |
| Analysis 4.8  Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 8 Mean birthweight. | ||||
| 8.1 Single interventions | 1 | 552 | Mean Difference (IV, Fixed, 95% CI) | ‐12.0 [‐102.29, 78.29] |
| 9 Perinatal deaths Show forest plot | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 4.40 [0.49, 39.08] |
| Analysis 4.9  Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 9 Perinatal deaths. | ||||
| 9.1 Single interventions | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 4.40 [0.49, 39.08] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 4 | 1282 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.85, 1.70] |
| Analysis 5.1  Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 2 | 853 | Risk Ratio (M‐H, Random, 95% CI) | 1.41 [0.99, 2.01] |
| 1.2 Multiple interventions | 1 | 198 | Risk Ratio (M‐H, Random, 95% CI) | 1.59 [0.68, 3.73] |
| 1.3 Tailored interventions | 1 | 231 | Risk Ratio (M‐H, Random, 95% CI) | 0.74 [0.44, 1.26] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 3 | 1082 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.70, 1.91] |
| Analysis 5.2  Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Single interventions | 1 | 653 | Risk Ratio (M‐H, Random, 95% CI) | 1.46 [0.88, 2.43] |
| 2.2 Multiple interventions | 1 | 198 | Risk Ratio (M‐H, Random, 95% CI) | 1.59 [0.68, 3.73] |
| 2.3 Tailored interventions | 1 | 231 | Risk Ratio (M‐H, Random, 95% CI) | 0.74 [0.44, 1.26] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 2 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 5.3  Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 3 Abstinence at 0 to 5 months postpartum. | ||||
| 3.1 Single interventions | 2 | 844 | Risk Ratio (M‐H, Random, 95% CI) | 1.55 [1.01, 2.36] |
| 4 Mean cigarettes per day in late pregnancy Show forest plot | 1 | 127 | Mean Difference (IV, Random, 95% CI) | ‐0.70 [‐3.37, 1.97] |
| Analysis 5.4  Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 4 Mean cigarettes per day in late pregnancy. | ||||
| 4.1 Tailored interventions | 1 | 127 | Mean Difference (IV, Random, 95% CI) | ‐0.70 [‐3.37, 1.97] |
| 5 Low birthweight (< 2500 g) Show forest plot | 1 | 620 | Risk Ratio (M‐H, Random, 95% CI) | 0.60 [0.28, 1.29] |
| Analysis 5.5  Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 5 Low birthweight (< 2500 g). | ||||
| 5.1 Single interventions | 1 | 620 | Risk Ratio (M‐H, Random, 95% CI) | 0.60 [0.28, 1.29] |
| 6 Preterm births Show forest plot | 1 | 618 | Risk Ratio (M‐H, Random, 95% CI) | 0.76 [0.32, 1.80] |
| Analysis 5.6  Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 6 Preterm births. | ||||
| 6.1 Single interventions | 1 | 618 | Risk Ratio (M‐H, Random, 95% CI) | 0.76 [0.32, 1.80] |
| 7 Mean birthweight Show forest plot | 1 | 620 | Mean Difference (IV, Fixed, 95% CI) | 71.0 [‐26.58, 168.58] |
| Analysis 5.7  Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 7 Mean birthweight. | ||||
| 7.1 Single interventions | 1 | 620 | Mean Difference (IV, Fixed, 95% CI) | 71.0 [‐26.58, 168.58] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 1 | 31 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [0.19, 18.60] |
| Analysis 6.1  Comparison 6 Smoking cessation interventions: health education vs alternative intervention, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 1 | 31 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [0.19, 18.60] |
| 2 Abstinence in late pregnancy: biochemically validated Show forest plot | 1 | 31 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [0.19, 18.60] |
| Analysis 6.2  Comparison 6 Smoking cessation interventions: health education vs alternative intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated. | ||||
| 2.1 Single interventions | 1 | 31 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [0.19, 18.60] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 2 | 355 | Risk Ratio (M‐H, Random, 95% CI) | 4.39 [1.89, 10.21] |
| Analysis 7.1  Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Multiple interventions | 2 | 355 | Risk Ratio (M‐H, Random, 95% CI) | 4.39 [1.89, 10.21] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 1 | 244 | Risk Ratio (M‐H, Random, 95% CI) | 3.88 [1.38, 10.93] |
| Analysis 7.2  Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Multiple interventions | 1 | 244 | Risk Ratio (M‐H, Random, 95% CI) | 3.88 [1.38, 10.93] |
| 3 Reduction in late pregnancy: biochemically validated Show forest plot | 1 | 244 | Risk Ratio (M‐H, Random, 95% CI) | 1.48 [0.93, 2.37] |
| Analysis 7.3  Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 3 Reduction in late pregnancy: biochemically validated. | ||||
| 3.1 Multiple interventions | 1 | 244 | Risk Ratio (M‐H, Random, 95% CI) | 1.48 [0.93, 2.37] |
| 4 Reduction in late pregnancy: self‐reported (various definitions) Show forest plot | 1 | 111 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [1.24, 2.84] |
| Analysis 7.4  Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 4 Reduction in late pregnancy: self‐reported (various definitions). | ||||
| 4.1 Multiple interventions | 1 | 111 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [1.24, 2.84] |
| 5 Mean cigarettes per day in late pregnancy Show forest plot | 1 | 104 | Mean Difference (IV, Random, 95% CI) | ‐3.0 [‐4.68, ‐1.32] |
| Analysis 7.5  Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 5 Mean cigarettes per day in late pregnancy. | ||||
| 5.1 Multiple interventions | 1 | 104 | Mean Difference (IV, Random, 95% CI) | ‐3.0 [‐4.68, ‐1.32] |
| 6 Low birthweight (< 2500 g) Show forest plot | 1 | 2848 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.63, 1.06] |
| Analysis 7.6  Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 6 Low birthweight (< 2500 g). | ||||
| 6.1 Multiple interventions | 1 | 2848 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.63, 1.06] |
| 7 Preterm births Show forest plot | 2 | 3111 | Risk Ratio (M‐H, Random, 95% CI) | 0.60 [0.28, 1.29] |
| Analysis 7.7  Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 7 Preterm births. | ||||
| 7.1 Multiple interventions | 2 | 3111 | Risk Ratio (M‐H, Random, 95% CI) | 0.60 [0.28, 1.29] |
| 8 Mean birthweight Show forest plot | 2 | 3006 | Mean Difference (IV, Random, 95% CI) | 79.43 [‐53.05, 211.91] |
| Analysis 7.8  Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 8 Mean birthweight. | ||||
| 8.1 Multiple interventions | 2 | 3006 | Mean Difference (IV, Random, 95% CI) | 79.43 [‐53.05, 211.91] |
| 9 Stillbirths Show forest plot | 2 | 2960 | Risk Ratio (M‐H, Random, 95% CI) | 1.28 [0.69, 2.39] |
| Analysis 7.9  Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 9 Stillbirths. | ||||
| 9.1 Multiple interventions | 2 | 2960 | Risk Ratio (M‐H, Random, 95% CI) | 1.28 [0.69, 2.39] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 3 | 439 | Risk Ratio (M‐H, Random, 95% CI) | 1.29 [0.75, 2.20] |
| Analysis 8.1  Comparison 8 Smoking cessation interventions: feedback vs less intensive intervention, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 2 | 259 | Risk Ratio (M‐H, Random, 95% CI) | 1.06 [0.48, 2.36] |
| 1.2 Multiple interventions | 1 | 180 | Risk Ratio (M‐H, Random, 95% CI) | 1.57 [0.71, 3.47] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 3 | 439 | Risk Ratio (M‐H, Random, 95% CI) | 1.29 [0.75, 2.20] |
| Analysis 8.2  Comparison 8 Smoking cessation interventions: feedback vs less intensive intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Single interventions | 2 | 259 | Risk Ratio (M‐H, Random, 95% CI) | 1.06 [0.48, 2.36] |
| 2.2 Multiple interventions | 1 | 180 | Risk Ratio (M‐H, Random, 95% CI) | 1.57 [0.71, 3.47] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 5 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 9.1  Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 3 | 731 | Risk Ratio (M‐H, Random, 95% CI) | 2.73 [1.72, 4.35] |
| 1.2 Multiple interventions | 1 | 41 | Risk Ratio (M‐H, Random, 95% CI) | 0.83 [0.17, 3.93] |
| 1.3 Tailored interventions | 1 | 41 | Risk Ratio (M‐H, Random, 95% CI) | 0.70 [0.13, 3.68] |
| 2 Abstinence in late pregnancy:biochemically validated only Show forest plot | 5 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 9.2  Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 2 Abstinence in late pregnancy:biochemically validated only. | ||||
| 2.1 Single interventions | 3 | 731 | Risk Ratio (M‐H, Random, 95% CI) | 2.73 [1.72, 4.35] |
| 2.2 Multiple interventions | 1 | 41 | Risk Ratio (M‐H, Random, 95% CI) | 0.83 [0.17, 3.93] |
| 2.3 Tailored interventions | 1 | 41 | Risk Ratio (M‐H, Random, 95% CI) | 0.70 [0.13, 3.68] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 2 | 150 | Risk Ratio (M‐H, Random, 95% CI) | 1.09 [0.56, 2.13] |
| Analysis 9.3  Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 3 Abstinence at 0 to 5 months postpartum. | ||||
| 3.1 Multiple interventions | 2 | 150 | Risk Ratio (M‐H, Random, 95% CI) | 1.09 [0.56, 2.13] |
| 4 Abstinence at 6 to 11 months postpartum Show forest plot | 1 | 609 | Risk Ratio (M‐H, Random, 95% CI) | 3.88 [2.10, 7.16] |
| Analysis 9.4  Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 4 Abstinence at 6 to 11 months postpartum. | ||||
| 4.1 Single interventions | 1 | 609 | Risk Ratio (M‐H, Random, 95% CI) | 3.88 [2.10, 7.16] |
| 5 Reduction in late pregnancy: biochemically validated Show forest plot | 2 | Risk Ratio (M‐H, Random, 95% CI) | Totals not selected | |
| Analysis 9.5  Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 5 Reduction in late pregnancy: biochemically validated. | ||||
| 5.1 Single interventions | 2 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 6 Biochemical measures in late pregnancy: mean cotinine Show forest plot | 2 | 102 | Mean Difference (IV, Random, 95% CI) | ‐2.00 [‐6.61, 2.60] |
| Analysis 9.6  Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 6 Biochemical measures in late pregnancy: mean cotinine. | ||||
| 6.1 Single interventions | 2 | 102 | Mean Difference (IV, Random, 95% CI) | ‐2.00 [‐6.61, 2.60] |
| 7 Mean cigarettes per day in late pregnancy Show forest plot | 1 | 74 | Mean Difference (IV, Random, 95% CI) | ‐8.2 [‐10.83, ‐5.57] |
| Analysis 9.7  Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 7 Mean cigarettes per day in late pregnancy. | ||||
| 7.1 Single interventions | 1 | 74 | Mean Difference (IV, Random, 95% CI) | ‐8.2 [‐10.83, ‐5.57] |
| 8 Low birthweight Show forest plot | 4 | 215 | Risk Ratio (M‐H, Random, 95% CI) | 0.70 [0.40, 1.23] |
| Analysis 9.8  Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 8 Low birthweight. | ||||
| 8.1 Single interventions | 2 | 68 | Risk Ratio (M‐H, Random, 95% CI) | 0.64 [0.32, 1.28] |
| 8.2 Multiple interventions | 2 | 147 | Risk Ratio (M‐H, Random, 95% CI) | 0.84 [0.32, 2.21] |
| 9 Preterm births Show forest plot | 5 | 753 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.73, 1.82] |
| Analysis 9.9  Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 9 Preterm births. | ||||
| 9.1 Single interventions | 3 | 606 | Risk Ratio (M‐H, Random, 95% CI) | 1.30 [0.77, 2.18] |
| 9.2 Multiple interventions | 2 | 147 | Risk Ratio (M‐H, Random, 95% CI) | 0.61 [0.21, 1.77] |
| 10 Mean birthweight Show forest plot | 5 | 797 | Mean Difference (IV, Random, 95% CI) | 109.38 [60.51, 158.26] |
| Analysis 9.10  Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 10 Mean birthweight. | ||||
| 10.1 Single interventions | 3 | 650 | Mean Difference (IV, Random, 95% CI) | 41.69 [‐50.96, 134.33] |
| 10.2 Multiple interventions | 2 | 147 | Mean Difference (IV, Random, 95% CI) | 126.49 [67.80, 185.19] |
| 11 NICU admissions Show forest plot | 2 | 68 | Risk Ratio (M‐H, Random, 95% CI) | 0.80 [0.51, 1.26] |
| Analysis 9.11  Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 11 NICU admissions. | ||||
| 11.1 Single interventions | 2 | 68 | Risk Ratio (M‐H, Random, 95% CI) | 0.80 [0.51, 1.26] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 4 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 10.1  Comparison 10 Smoking cessation interventions: incentives vs less intensive intervention, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 3 | 731 | Risk Ratio (M‐H, Random, 95% CI) | 0.81 [0.59, 1.12] |
| 1.2 Multiple interventions | 1 | 220 | Risk Ratio (M‐H, Random, 95% CI) | 3.64 [1.84, 7.23] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 4 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 10.2  Comparison 10 Smoking cessation interventions: incentives vs less intensive intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Single interventions | 3 | 731 | Risk Ratio (M‐H, Random, 95% CI) | 0.81 [0.59, 1.12] |
| 2.2 Multiple interventions | 1 | 220 | Risk Ratio (M‐H, Random, 95% CI) | 3.64 [1.84, 7.23] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 1 | 205 | Risk Ratio (M‐H, Random, 95% CI) | 3.63 [1.54, 8.58] |
| Analysis 10.3  Comparison 10 Smoking cessation interventions: incentives vs less intensive intervention, Outcome 3 Abstinence at 0 to 5 months postpartum. | ||||
| 3.1 Multiple interventions | 1 | 205 | Risk Ratio (M‐H, Random, 95% CI) | 3.63 [1.54, 8.58] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 4 | 212 | Risk Ratio (M‐H, Random, 95% CI) | 2.36 [1.36, 4.09] |
| Analysis 11.1  Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 2 | 94 | Risk Ratio (M‐H, Random, 95% CI) | 2.19 [0.53, 9.04] |
| 1.2 Multiple interventions | 2 | 118 | Risk Ratio (M‐H, Random, 95% CI) | 2.20 [1.06, 4.55] |
| 2 Abstinence in late pregnancy: biochemicaly validated only Show forest plot | 4 | 212 | Risk Ratio (M‐H, Random, 95% CI) | 2.36 [1.36, 4.09] |
| Analysis 11.2  Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 2 Abstinence in late pregnancy: biochemicaly validated only. | ||||
| 2.1 Single interventions | 2 | 94 | Risk Ratio (M‐H, Random, 95% CI) | 2.19 [0.53, 9.04] |
| 2.2 Multiple interventions | 2 | 118 | Risk Ratio (M‐H, Random, 95% CI) | 2.20 [1.06, 4.55] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 3 | 195 | Risk Ratio (M‐H, Random, 95% CI) | 1.79 [0.57, 5.61] |
| Analysis 11.3  Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 3 Abstinence at 0 to 5 months postpartum. | ||||
| 3.1 Single interventions | 1 | 77 | Risk Ratio (M‐H, Random, 95% CI) | 9.73 [1.29, 73.13] |
| 3.2 Multiple interventions | 2 | 118 | Risk Ratio (M‐H, Random, 95% CI) | 1.13 [0.51, 2.52] |
| 4 Abstinence at 6 to 11 months postpartum Show forest plot | 3 | 195 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.85, 1.01] |
| Analysis 11.4  Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 4 Abstinence at 6 to 11 months postpartum. | ||||
| 4.1 Single interventions | 1 | 77 | Risk Ratio (M‐H, Random, 95% CI) | 0.94 [0.85, 1.05] |
| 4.2 Multiple interventions | 2 | 118 | Risk Ratio (M‐H, Random, 95% CI) | 0.90 [0.79, 1.03] |
| 5 Smoking reduction: numbers of women reducing smoking in late pregnancy (biochemically validated) Show forest plot | 1 | 17 | Risk Ratio (M‐H, Random, 95% CI) | 0.71 [0.18, 2.88] |
| Analysis 11.5  Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 5 Smoking reduction: numbers of women reducing smoking in late pregnancy (biochemically validated). | ||||
| 5.1 Single interventions | 1 | 17 | Risk Ratio (M‐H, Random, 95% CI) | 0.71 [0.18, 2.88] |
| 6 Low birthweight (under 2500 g) Show forest plot | 3 | 184 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.60 [0.26, 1.40] |
| Analysis 11.6  Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 6 Low birthweight (under 2500 g). | ||||
| 6.1 Single interventions | 1 | 73 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.43 [0.12, 1.49] |
| 6.2 Multiple interventions | 2 | 111 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.84 [0.26, 2.69] |
| 7 Preterm birth (under 37 weeks) Show forest plot | 3 | 184 | Risk Ratio (M‐H, Random, 95% CI) | 0.48 [0.20, 1.14] |
| Analysis 11.7  Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 7 Preterm birth (under 37 weeks). | ||||
| 7.1 Single interventions | 1 | 73 | Risk Ratio (M‐H, Random, 95% CI) | 0.38 [0.11, 1.30] |
| 7.2 Multiple interventions | 2 | 111 | Risk Ratio (M‐H, Random, 95% CI) | 0.60 [0.17, 2.12] |
| 8 Mean birthweight Show forest plot | 3 | 184 | Mean Difference (IV, Random, 95% CI) | 134.58 [76.32, 192.83] |
| Analysis 11.8  Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 8 Mean birthweight. | ||||
| 8.1 Single interventions | 1 | 73 | Mean Difference (IV, Random, 95% CI) | 253.0 [‐3.67, 509.67] |
| 8.2 Multiple interventions | 2 | 111 | Mean Difference (IV, Random, 95% CI) | 128.48 [65.86, 191.10] |
| 9 NICU admissions Show forest plot | 3 | 184 | Risk Ratio (M‐H, Random, 95% CI) | 0.64 [0.26, 1.55] |
| Analysis 11.9  Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 9 NICU admissions. | ||||
| 9.1 Single interventions | 1 | 73 | Risk Ratio (M‐H, Random, 95% CI) | 0.76 [0.24, 2.49] |
| 9.2 Multiple interventions | 2 | 111 | Risk Ratio (M‐H, Random, 95% CI) | 0.49 [0.13, 1.95] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 7 | 781 | Risk Ratio (M‐H, Random, 95% CI) | 1.21 [0.93, 1.58] |
| Analysis 12.1  Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 2 | 224 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [0.57, 3.18] |
| 1.2 Multiple interventions | 4 | 406 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [0.83, 2.18] |
| 1.3 Tailored interventions | 1 | 151 | Risk Ratio (M‐H, Random, 95% CI) | 1.22 [0.59, 2.52] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 6 | 601 | Risk Ratio (M‐H, Random, 95% CI) | 1.42 [0.98, 2.07] |
| Analysis 12.2  Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Single interventions | 2 | 224 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [0.57, 3.18] |
| 2.2 Multiple interventions | 3 | 226 | Risk Ratio (M‐H, Random, 95% CI) | 1.93 [1.00, 3.74] |
| 2.3 Tailored interventions | 1 | 151 | Risk Ratio (M‐H, Random, 95% CI) | 1.22 [0.59, 2.52] |
| 3 Continued abstinence (relapse prevention) in late pregnancy Show forest plot | 1 | 211 | Risk Ratio (M‐H, Random, 95% CI) | 1.02 [0.89, 1.16] |
| Analysis 12.3  Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 3 Continued abstinence (relapse prevention) in late pregnancy. | ||||
| 3.1 Multiple interventions | 1 | 211 | Risk Ratio (M‐H, Random, 95% CI) | 1.02 [0.89, 1.16] |
| 4 Abstinence at 0 to 5 months postpartum Show forest plot | 2 | 472 | Risk Ratio (M‐H, Random, 95% CI) | 1.34 [0.35, 5.14] |
| Analysis 12.4  Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 4 Abstinence at 0 to 5 months postpartum. | ||||
| 4.1 Single interventions | 1 | 82 | Risk Ratio (M‐H, Random, 95% CI) | 5.8 [0.33, 101.27] |
| 4.2 Multiple interventions | 1 | 390 | Risk Ratio (M‐H, Random, 95% CI) | 0.98 [0.74, 1.31] |
| 5 Abstinence at 6 to 11 months postpartum Show forest plot | 3 | 533 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.81, 1.44] |
| Analysis 12.5  Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 5 Abstinence at 6 to 11 months postpartum. | ||||
| 5.1 Multiple interventions | 3 | 533 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.81, 1.44] |
| 6 Abstinence at 12 to 17 months postpartum Show forest plot | 1 | 391 | Risk Ratio (M‐H, Random, 95% CI) | 1.07 [0.76, 1.51] |
| Analysis 12.6  Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 6 Abstinence at 12 to 17 months postpartum. | ||||
| 6.1 Multiple interventions | 1 | 391 | Risk Ratio (M‐H, Random, 95% CI) | 1.07 [0.76, 1.51] |
| 7 Smoking reduction: self reported > 50% reduction Show forest plot | 1 | 151 | Risk Ratio (M‐H, Random, 95% CI) | 0.96 [0.64, 1.44] |
| Analysis 12.7  Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 7 Smoking reduction: self reported > 50% reduction. | ||||
| 7.1 Tailored interventions | 1 | 151 | Risk Ratio (M‐H, Random, 95% CI) | 0.96 [0.64, 1.44] |
| 8 Low birthweight (< 2500 g) Show forest plot | 1 | 79 | Risk Ratio (M‐H, Random, 95% CI) | 1.00 [0.33, 2.99] |
| Analysis 12.8  Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 8 Low birthweight (< 2500 g). | ||||
| 8.1 Single interventions | 1 | 79 | Risk Ratio (M‐H, Random, 95% CI) | 1.00 [0.33, 2.99] |
| 9 Mean birthweight Show forest plot | 1 | 142 | Mean Difference (IV, Fixed, 95% CI) | 28.0 [‐152.48, 208.48] |
| Analysis 12.9  Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 9 Mean birthweight. | ||||
| 9.1 Single interventions | 1 | 142 | Mean Difference (IV, Fixed, 95% CI) | 28.0 [‐152.48, 208.48] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.72, 2.01] |
| Analysis 13.1  Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.72, 2.01] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.72, 2.01] |
| Analysis 13.2  Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Single interventions | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.72, 2.01] |
| 3 Abstinence at 6 to 11 months postpartum Show forest plot | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.50 [0.81, 2.79] |
| Analysis 13.3  Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 3 Abstinence at 6 to 11 months postpartum. | ||||
| 3.1 Single interventions | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.50 [0.81, 2.79] |
| 4 Low birthweight Show forest plot | 1 | 712 | Risk Ratio (M‐H, Random, 95% CI) | 0.88 [0.58, 1.32] |
| Analysis 13.4  Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 4 Low birthweight. | ||||
| 4.1 Single interventions | 1 | 712 | Risk Ratio (M‐H, Random, 95% CI) | 0.88 [0.58, 1.32] |
| 5 Preterm births Show forest plot | 1 | 704 | Risk Ratio (M‐H, Random, 95% CI) | 1.32 [0.81, 2.14] |
| Analysis 13.5  Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 5 Preterm births. | ||||
| 5.1 Single interventions | 1 | 704 | Risk Ratio (M‐H, Random, 95% CI) | 1.32 [0.81, 2.14] |
| 6 Mean birthweight Show forest plot | 1 | 713 | Mean Difference (IV, Random, 95% CI) | ‐14.40 [‐104.15, 75.35] |
| Analysis 13.6  Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 6 Mean birthweight. | ||||
| 6.1 Single interventions | 1 | 713 | Mean Difference (IV, Random, 95% CI) | ‐14.40 [‐104.15, 75.35] |
| 7 Stillbirths Show forest plot | 1 | 756 | Risk Ratio (M‐H, Random, 95% CI) | 1.01 [0.14, 7.10] |
| Analysis 13.7  Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 7 Stillbirths. | ||||
| 7.1 Single interventions | 1 | 756 | Risk Ratio (M‐H, Random, 95% CI) | 1.01 [0.14, 7.10] |
| 8 Neonatal deaths Show forest plot | 1 | 775 | Risk Ratio (M‐H, Random, 95% CI) | 0.34 [0.01, 8.31] |
| Analysis 13.8  Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 8 Neonatal deaths. | ||||
| 8.1 Single interventions | 1 | 775 | Risk Ratio (M‐H, Random, 95% CI) | 0.34 [0.01, 8.31] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 1 | 194 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.62, 4.32] |
| Analysis 14.1  Comparison 14 Smoking cessation interventions: other vs usual care, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 1 | 194 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.62, 4.32] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 1 | 194 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.62, 4.32] |
| Analysis 14.2  Comparison 14 Smoking cessation interventions: other vs usual care, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Single interventions | 1 | 194 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.62, 4.32] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 2 | 258 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.69, 1.25] |
| Analysis 15.1  Comparison 15 Maternal health intervention with smoking cessation component: counselling vs usual care, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single | 2 | 258 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.69, 1.25] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 1 | 198 | Risk Ratio (M‐H, Random, 95% CI) | 1.00 [0.72, 1.40] |
| Analysis 15.2  Comparison 15 Maternal health intervention with smoking cessation component: counselling vs usual care, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Single | 1 | 198 | Risk Ratio (M‐H, Random, 95% CI) | 1.00 [0.72, 1.40] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 1 | 198 | Risk Ratio (M‐H, Random, 95% CI) | 1.46 [0.97, 2.19] |
| Analysis 15.3  Comparison 15 Maternal health intervention with smoking cessation component: counselling vs usual care, Outcome 3 Abstinence at 0 to 5 months postpartum. | ||||
| 3.1 Single interventions | 1 | 198 | Risk Ratio (M‐H, Random, 95% CI) | 1.46 [0.97, 2.19] |
| 4 Smoking reduction: biochemical measures in late pregnancy Show forest plot | 1 | 198 | Std. Mean Difference (IV, Random, 95% CI) | 0.11 [‐0.17, 0.39] |
| Analysis 15.4  Comparison 15 Maternal health intervention with smoking cessation component: counselling vs usual care, Outcome 4 Smoking reduction: biochemical measures in late pregnancy. | ||||
| 4.1 Mean cotinine | 1 | 198 | Std. Mean Difference (IV, Random, 95% CI) | 0.11 [‐0.17, 0.39] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy: biochemically validated only Show forest plot | 1 | 530 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.65, 1.32] |
| Analysis 16.1  Comparison 16 Maternal health intervention with smoking cessation component: health education vs less intensive intervention, Outcome 1 Abstinence in late pregnancy: biochemically validated only. | ||||
| 1.1 Single interventions | 1 | 530 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.65, 1.32] |
| 2 Abstinence at 0 to 5 months postpartum Show forest plot | 1 | 530 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.67, 1.65] |
| Analysis 16.2  Comparison 16 Maternal health intervention with smoking cessation component: health education vs less intensive intervention, Outcome 2 Abstinence at 0 to 5 months postpartum. | ||||
| 2.1 Single interventions | 1 | 530 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.67, 1.65] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Smoking abstinence in late pregnancy Show forest plot | 1 | 65 | Risk Ratio (M‐H, Random, 95% CI) | 2.11 [0.98, 4.57] |
| Analysis 17.1  Comparison 17 Maternal health intervention with smoking cessation component: feedback vs usual care, Outcome 1 Smoking abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 1 | 65 | Risk Ratio (M‐H, Random, 95% CI) | 2.11 [0.98, 4.57] |
| 2 Smoking reduction in late pregnancy: self‐reported (various definitions) Show forest plot | 1 | 65 | Risk Ratio (M‐H, Random, 95% CI) | 0.95 [0.42, 2.18] |
| Analysis 17.2  Comparison 17 Maternal health intervention with smoking cessation component: feedback vs usual care, Outcome 2 Smoking reduction in late pregnancy: self‐reported (various definitions). | ||||
| 2.1 Single interventions | 1 | 65 | Risk Ratio (M‐H, Random, 95% CI) | 0.95 [0.42, 2.18] |
| 3 Smoking reduction: self‐reported mean cigarettes per day measured in late pregnancy or at delivery Show forest plot | 1 | 3571 | Mean Difference (IV, Random, 95% CI) | 1.5 [1.07, 1.93] |
| Analysis 17.3  Comparison 17 Maternal health intervention with smoking cessation component: feedback vs usual care, Outcome 3 Smoking reduction: self‐reported mean cigarettes per day measured in late pregnancy or at delivery. | ||||
| 3.1 Single interventions | 1 | 3571 | Mean Difference (IV, Random, 95% CI) | 1.5 [1.07, 1.93] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 4 | Risk Ratio (M‐H, Random, 95% CI) | Totals not selected | |
| Analysis 18.1  Comparison 18 Maternal health intervention with smoking cessation component: social support vs usual care, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 2 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 1.2 Tailored interventions | 2 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 2 Abstinence in late pregnancy:biochemically validated only Show forest plot | 3 | Risk Ratio (M‐H, Random, 95% CI) | Totals not selected | |
| Analysis 18.2  Comparison 18 Maternal health intervention with smoking cessation component: social support vs usual care, Outcome 2 Abstinence in late pregnancy:biochemically validated only. | ||||
| 2.1 Single interventions | 1 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 2.2 Multiple interventions | 0 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 2.3 Tailored interventions | 2 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 1 | 130 | Risk Ratio (M‐H, Random, 95% CI) | 1.23 [0.87, 1.74] |
| Analysis 18.3  Comparison 18 Maternal health intervention with smoking cessation component: social support vs usual care, Outcome 3 Abstinence at 0 to 5 months postpartum. | ||||
| 3.1 Single interventions | 1 | 130 | Risk Ratio (M‐H, Random, 95% CI) | 1.23 [0.87, 1.74] |
| 4 Abstinence at 18 + months postpartum Show forest plot | 1 | 73 | Risk Ratio (M‐H, Random, 95% CI) | 1.07 [0.58, 1.98] |
| Analysis 18.4  Comparison 18 Maternal health intervention with smoking cessation component: social support vs usual care, Outcome 4 Abstinence at 18 + months postpartum. | ||||
| 4.1 Multiple interventions | 1 | 73 | Risk Ratio (M‐H, Random, 95% CI) | 1.07 [0.58, 1.98] |
| 5 Smoking reduction: mean cigarettes per day Show forest plot | 2 | 271 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.31 [‐0.55, ‐0.07] |
| Analysis 18.5  Comparison 18 Maternal health intervention with smoking cessation component: social support vs usual care, Outcome 5 Smoking reduction: mean cigarettes per day. | ||||
| 5.1 Single interventions | 1 | 130 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.22 [‐0.57, 0.12] |
| 5.2 Tailored interventions | 1 | 141 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.40 [‐0.73, ‐0.06] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 3 | 455 | Risk Ratio (M‐H, Random, 95% CI) | 1.06 [0.68, 1.63] |
| Analysis 19.1  Comparison 19 Maternal health intervention with smoking cessation component: social support vs less intensive intervention, Outcome 1 Abstinence in late pregnancy. | ||||
| 1.1 Single interventions | 2 | 262 | Risk Ratio (M‐H, Random, 95% CI) | 0.98 [0.40, 2.39] |
| 1.2 Multiple interventions | 1 | 193 | Risk Ratio (M‐H, Random, 95% CI) | 0.99 [0.51, 1.92] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 2 | 389 | Risk Ratio (M‐H, Random, 95% CI) | 1.13 [0.72, 1.78] |
| Analysis 19.2  Comparison 19 Maternal health intervention with smoking cessation component: social support vs less intensive intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Single interventions | 1 | 196 | Risk Ratio (M‐H, Random, 95% CI) | 1.28 [0.68, 2.39] |
| 2.2 Multiple interventions | 1 | 193 | Risk Ratio (M‐H, Random, 95% CI) | 0.99 [0.51, 1.92] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 2 | 389 | Risk Ratio (M‐H, Random, 95% CI) | 0.89 [0.51, 1.55] |
| Analysis 19.3  Comparison 19 Maternal health intervention with smoking cessation component: social support vs less intensive intervention, Outcome 3 Abstinence at 0 to 5 months postpartum. | ||||
| 3.1 Single interventions | 1 | 196 | Risk Ratio (M‐H, Random, 95% CI) | 0.91 [0.41, 2.03] |
| 3.2 Multiple interventions | 1 | 193 | Risk Ratio (M‐H, Random, 95% CI) | 0.88 [0.41, 1.89] |
| 4 Smoking reduction: self reported mean cigarettes per day Show forest plot | 1 | 64 | Std. Mean Difference (IV, Fixed, 95% CI) | 0.15 [‐0.34, 0.64] |
| Analysis 19.4  Comparison 19 Maternal health intervention with smoking cessation component: social support vs less intensive intervention, Outcome 4 Smoking reduction: self reported mean cigarettes per day. | ||||
| 4.1 Single interventions | 1 | 64 | Std. Mean Difference (IV, Fixed, 95% CI) | 0.15 [‐0.34, 0.64] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy: self‐reported and biochemically validated Show forest plot | 97 | 26637 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [1.23, 1.48] |
| Analysis 20.1  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 1 Abstinence in late pregnancy: self‐reported and biochemically validated. | ||||
| 1.1 Counselling | 51 | 18276 | Risk Ratio (M‐H, Random, 95% CI) | 1.31 [1.16, 1.47] |
| 1.2 Health education | 11 | 2142 | Risk Ratio (M‐H, Random, 95% CI) | 1.22 [0.97, 1.55] |
| 1.3 Feedback | 6 | 859 | Risk Ratio (M‐H, Random, 95% CI) | 1.92 [1.16, 3.17] |
| 1.4 Incentives | 13 | 1752 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [1.12, 3.14] |
| 1.5 Social support | 14 | 2629 | Risk Ratio (M‐H, Random, 95% CI) | 1.16 [0.96, 1.40] |
| 1.6 Exercise | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.72, 2.01] |
| 1.7 Other | 1 | 194 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.62, 4.32] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 73 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 20.2  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 2 Abstinence in late pregnancy: biochemically validated only. | ||||
| 2.1 Counselling | 37 | 14521 | Risk Ratio (M‐H, Random, 95% CI) | 1.23 [1.10, 1.38] |
| 2.2 Health education | 8 | 1744 | Risk Ratio (M‐H, Random, 95% CI) | 1.16 [0.87, 1.55] |
| 2.3 Feedback | 4 | 683 | Risk Ratio (M‐H, Random, 95% CI) | 1.60 [0.85, 3.03] |
| 2.4 Incentives | 13 | 1788 | Risk Ratio (M‐H, Random, 95% CI) | 1.82 [1.10, 3.03] |
| 2.5 Social support | 9 | 1723 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.94, 1.24] |
| 2.6 Exercise | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.72, 2.01] |
| 2.7 Other | 1 | 194 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.62, 4.32] |
| 3 Continued abstinence (Relapse prevention) in late pregnancy for spontaneous quitters Show forest plot | 15 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 20.3  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 3 Continued abstinence (Relapse prevention) in late pregnancy for spontaneous quitters. | ||||
| 3.1 Counselling | 13 | 1538 | Risk Ratio (M‐H, Random, 95% CI) | 1.01 [0.92, 1.09] |
| 3.2 Health education | 1 | 70 | Risk Ratio (M‐H, Random, 95% CI) | 1.02 [0.86, 1.23] |
| 3.3 Social support | 1 | 158 | Risk Ratio (M‐H, Random, 95% CI) | 1.01 [0.86, 1.20] |
| 4 Abstinence at 0 to 5 months postpartum Show forest plot | 35 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 20.4  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 4 Abstinence at 0 to 5 months postpartum. | ||||
| 4.1 Counselling | 21 | 5891 | Risk Ratio (M‐H, Random, 95% CI) | 1.29 [1.13, 1.46] |
| 4.2 Health education | 5 | 1378 | Risk Ratio (M‐H, Random, 95% CI) | 1.50 [1.02, 2.20] |
| 4.3 Incentives | 4 | 400 | Risk Ratio (M‐H, Random, 95% CI) | 2.23 [0.94, 5.30] |
| 4.4 Social support | 5 | 697 | Risk Ratio (M‐H, Random, 95% CI) | 1.09 [0.86, 1.37] |
| 5 Abstinence at 6 to 11 months postpartum Show forest plot | 19 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 20.5  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 5 Abstinence at 6 to 11 months postpartum. | ||||
| 5.1 Counselling | 11 | 4277 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.98, 1.34] |
| 5.2 Incentives | 4 | 804 | Risk Ratio (M‐H, Random, 95% CI) | 3.39 [1.99, 5.76] |
| 5.3 Social support | 3 | 434 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.75, 1.49] |
| 5.4 Exercise | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.50 [0.81, 2.79] |
| 6 Abstinence at 12 to 17 months postpartum Show forest plot | 6 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 20.6  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 6 Abstinence at 12 to 17 months postpartum. | ||||
| 6.1 Counselling | 5 | 1910 | Risk Ratio (M‐H, Random, 95% CI) | 1.37 [0.98, 1.91] |
| 6.2 Social support | 1 | 292 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.69, 1.60] |
| 7 Abstinence at 18+ months postpartum Show forest plot | 4 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 20.7  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 7 Abstinence at 18+ months postpartum. | ||||
| 7.1 Counselling | 3 | 798 | Risk Ratio (M‐H, Random, 95% CI) | 0.98 [0.50, 1.92] |
| 7.2 Social support | 1 | 73 | Risk Ratio (M‐H, Random, 95% CI) | 1.07 [0.58, 1.98] |
| 8 Smoking reduction: numbers of women reducing smoking in late pregnancy Show forest plot | 18 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| Analysis 20.8  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 8 Smoking reduction: numbers of women reducing smoking in late pregnancy. | ||||
| 8.1 Biochemically validated reduction | 10 | 2531 | Risk Ratio (M‐H, Random, 95% CI) | 1.26 [0.93, 1.71] |
| 8.2 Self‐reported some reduction in smoking (various definitions) | 4 | 499 | Risk Ratio (M‐H, Random, 95% CI) | 1.61 [1.22, 2.12] |
| 8.3 Self‐reported > 50% reduction in smoking | 4 | 1872 | Risk Ratio (M‐H, Random, 95% CI) | 1.29 [1.08, 1.54] |
| 9 Smoking reduction: biochemical measures in late pregnancy Show forest plot | 10 | Std. Mean Difference (IV, Random, 95% CI) | Subtotals only | |
| Analysis 20.9  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 9 Smoking reduction: biochemical measures in late pregnancy. | ||||
| 9.1 Mean cotinine levels | 9 | 2258 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.41 [‐0.66, ‐0.15] |
| 9.2 Mean thiocyanate level | 1 | 769 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.29 [‐0.44, ‐0.15] |
| 10 Smoking reduction: self‐reported mean cigarettes per day measured in late pregnancy or at delivery Show forest plot | 24 | Std. Mean Difference (IV, Random, 95% CI) | Subtotals only | |
| Analysis 20.10  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 10 Smoking reduction: self‐reported mean cigarettes per day measured in late pregnancy or at delivery. | ||||
| 10.1 Counselling | 13 | 3814 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.19 [‐0.36, ‐0.01] |
| 10.2 Health education | 4 | 1436 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.29 [‐0.71, 0.14] |
| 10.3 Feedback | 2 | 3675 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.18 [‐1.02, 0.67] |
| 10.4 Incentives | 1 | 74 | Std. Mean Difference (IV, Random, 95% CI) | ‐1.43 [‐1.94, ‐0.91] |
| 10.5 Social support | 4 | 736 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.23 [‐0.39, ‐0.07] |
| 11 Low birthweight (under 2500 g) Show forest plot | 18 | 9402 | Risk Ratio (M‐H, Random, 95% CI) | 0.83 [0.72, 0.94] |
| Analysis 20.11  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 11 Low birthweight (under 2500 g). | ||||
| 11.1 Counselling | 8 | 4339 | Risk Ratio (M‐H, Random, 95% CI) | 0.83 [0.68, 1.01] |
| 11.2 Health education | 2 | 1172 | Risk Ratio (M‐H, Random, 95% CI) | 0.87 [0.49, 1.55] |
| 11.3 Feedback | 1 | 2848 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.63, 1.06] |
| 11.4 Incentives | 5 | 252 | Risk Ratio (M‐H, Random, 95% CI) | 0.63 [0.37, 1.08] |
| 11.5 Social support | 1 | 79 | Risk Ratio (M‐H, Random, 95% CI) | 1.00 [0.33, 2.99] |
| 11.6 Exercise | 1 | 712 | Risk Ratio (M‐H, Random, 95% CI) | 0.88 [0.58, 1.32] |
| 12 Very low birthweight (under 1500 g) Show forest plot | 3 | 4366 | Risk Ratio (M‐H, Random, 95% CI) | 1.11 [0.62, 2.01] |
| Analysis 20.12  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 12 Very low birthweight (under 1500 g). | ||||
| 12.1 Counselling | 2 | 1666 | Risk Ratio (M‐H, Random, 95% CI) | 1.27 [0.60, 2.71] |
| 12.2 Feedback | 1 | 2700 | Risk Ratio (M‐H, Random, 95% CI) | 0.90 [0.35, 2.32] |
| 13 Preterm birth (under 37 weeks) Show forest plot | 19 | 9222 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.77, 1.11] |
| Analysis 20.13  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 13 Preterm birth (under 37 weeks). | ||||
| 13.1 Counselling | 8 | 3447 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.71, 1.20] |
| 13.2 Health education | 2 | 1170 | Risk Ratio (M‐H, Random, 95% CI) | 0.92 [0.55, 1.56] |
| 13.3 Feedback | 2 | 3111 | Risk Ratio (M‐H, Random, 95% CI) | 0.60 [0.28, 1.29] |
| 13.4 Incentives | 6 | 790 | Risk Ratio (M‐H, Random, 95% CI) | 0.91 [0.52, 1.59] |
| 13.5 Exercise | 1 | 704 | Risk Ratio (M‐H, Random, 95% CI) | 1.32 [0.81, 2.14] |
| 14 Mean birthweight (g) Show forest plot | 26 | 11338 | Mean Difference (IV, Random, 95% CI) | 55.60 [29.82, 81.38] |
| Analysis 20.14  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 14 Mean birthweight (g). | ||||
| 14.1 Counselling | 14 | 5471 | Mean Difference (IV, Random, 95% CI) | 42.17 [11.79, 72.55] |
| 14.2 Health education | 2 | 1172 | Mean Difference (IV, Random, 95% CI) | 27.35 [‐53.88, 108.58] |
| 14.3 Feedback | 2 | 3006 | Mean Difference (IV, Random, 95% CI) | 79.43 [‐53.05, 211.91] |
| 14.4 Incentives | 6 | 834 | Mean Difference (IV, Random, 95% CI) | 114.01 [63.91, 164.11] |
| 14.5 Social support | 1 | 142 | Mean Difference (IV, Random, 95% CI) | 28.0 [‐152.48, 208.48] |
| 14.6 Exercise | 1 | 713 | Mean Difference (IV, Random, 95% CI) | ‐14.40 [‐104.15, 75.35] |
| 15 Stillbirths Show forest plot | 8 | 6170 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.76, 1.90] |
| Analysis 20.15  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 15 Stillbirths. | ||||
| 15.1 Counselling | 5 | 2454 | Risk Ratio (M‐H, Random, 95% CI) | 1.14 [0.55, 2.33] |
| 15.2 Feedback | 2 | 2960 | Risk Ratio (M‐H, Random, 95% CI) | 1.28 [0.69, 2.39] |
| 15.3 Exercise | 1 | 756 | Risk Ratio (M‐H, Random, 95% CI) | 1.01 [0.14, 7.10] |
| 16 Perinatal deaths Show forest plot | 4 | 4465 | Risk Ratio (M‐H, Random, 95% CI) | 1.13 [0.72, 1.77] |
| Analysis 20.16  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 16 Perinatal deaths. | ||||
| 16.1 Counselling | 2 | 1065 | Risk Ratio (M‐H, Random, 95% CI) | 1.10 [0.52, 2.31] |
| 16.2 Health education | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 4.40 [0.49, 39.08] |
| 16.3 Feedback | 1 | 2848 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.59, 1.87] |
| 17 Neonatal deaths Show forest plot | 5 | 5680 | Risk Ratio (M‐H, Random, 95% CI) | 1.04 [0.41, 2.64] |
| Analysis 20.17  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 17 Neonatal deaths. | ||||
| 17.1 Counselling | 3 | 2095 | Risk Ratio (M‐H, Random, 95% CI) | 2.06 [0.61, 6.92] |
| 17.2 Feedback | 1 | 2810 | Risk Ratio (M‐H, Random, 95% CI) | 0.40 [0.08, 2.07] |
| 17.3 Exercise | 1 | 775 | Risk Ratio (M‐H, Random, 95% CI) | 0.34 [0.01, 8.31] |
| 18 NICU admissions Show forest plot | 8 | 2100 | Risk Ratio (M‐H, Random, 95% CI) | 0.78 [0.61, 0.98] |
| Analysis 20.18  Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 18 NICU admissions. | ||||
| 18.1 Counselling | 2 | 1140 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.52, 1.29] |
| 18.2 Incentives | 5 | 252 | Risk Ratio (M‐H, Random, 95% CI) | 0.77 [0.51, 1.15] |
| 18.3 Exercise | 1 | 708 | Risk Ratio (M‐H, Random, 95% CI) | 0.76 [0.47, 1.22] |
Logic model for systematic review analysis of potential factors impacting on efficacy of interventions for supporting women to stop smoking in pregnancy.
Funnel plot of comparison: 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, outcome: 20.1 Abstinence in late pregnancy: self‐reported and biochemically validated.
Flow chart of included studies
Intensity (duration) of interventions and controls over time
Intensity (frequency) of interventions and controls over times
'Risk of bias' graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.
'Risk of bias' summary
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 1 Abstinence in late pregnancy.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 3 Continued abstinence (relapse prevention) in late pregnancy for spontaneous quitters.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 4 Abstinence at 0 to 5 months postpartum.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 5 Abstinence at 6 to 11 months postpartum.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 6 Abstinence at 12 to 17 months postpartum.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 7 Abstinence at 18+ months postpartum.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 8 Reduction in late pregnancy: biochemically validated.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 9 Reduction in late pregnancy: self reported (various definitions).
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 10 Biochemical measures in late pregnancy: mean cotinine.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 11 Mean cigarettes per day in late pregnancy.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 12 NICU admissions.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 13 Very low birthweight infants (< 1500 g).
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 14 Preterm births.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 15 Mean birthweight.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 16 Perinatal deaths.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 17 Stillbirths.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 18 Neonatal deaths.
Comparison 1 Smoking cessation interventions: counselling vs usual care, Outcome 19 Low birthweight infants (< 2500 g).
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 1 Abstinence in late pregnancy.
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 3 Continued abstinence (relapse prevention) in late pregnancy (spontaneous quitters).
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 4 Abstinence at 0 to 5 months postpartum.
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 5 Abstinence at 6 to 11 months postpartum.
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 6 Abstinence at 12 to 17 months postpartum.
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 7 Reduction in late pregnancy: biochemically validated.
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 8 Reduction in late pregnancy: self‐reported > 50%.
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 9 Mean cigarettes per day in late pregnancy.
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 10 Low birthweight infants (< 2500 g).
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 11 Preterm births.
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 12 Mean birthweight.
Comparison 2 Smoking cessation interventions: counselling vs less intensive intervention, Outcome 13 Stillbirths.
Comparison 3 Smoking cessation interventions: counselling vs alternative intervention, Outcome 1 Abstinence in late pregnancy.
Comparison 3 Smoking cessation interventions: counselling vs alternative intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 3 Smoking cessation interventions: counselling vs alternative intervention, Outcome 3 Abstinence at 0 to 5 months postpartum.
Comparison 3 Smoking cessation interventions: counselling vs alternative intervention, Outcome 4 Abstinence at 6 to 11 months postpartum.
Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 1 Abstinence in late pregnancy.
Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 3 Continued abstinence (Relapse prevention) in late pregnancy for spontaneous quitters.
Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 4 Abstinence at 0 to 5 months postpartum.
Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 5 Mean cigarettes per day in late pregnancy.
Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 6 Low birth weight.
Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 7 Preterm births (< 37 weeks).
Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 8 Mean birthweight.
Comparison 4 Smoking cessation interventions: health education vs usual care, Outcome 9 Perinatal deaths.
Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 1 Abstinence in late pregnancy.
Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 3 Abstinence at 0 to 5 months postpartum.
Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 4 Mean cigarettes per day in late pregnancy.
Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 5 Low birthweight (< 2500 g).
Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 6 Preterm births.
Comparison 5 Smoking cessation interventions: health education vs less intensive intervention, Outcome 7 Mean birthweight.
Comparison 6 Smoking cessation interventions: health education vs alternative intervention, Outcome 1 Abstinence in late pregnancy.
Comparison 6 Smoking cessation interventions: health education vs alternative intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated.
Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 1 Abstinence in late pregnancy.
Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 3 Reduction in late pregnancy: biochemically validated.
Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 4 Reduction in late pregnancy: self‐reported (various definitions).
Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 5 Mean cigarettes per day in late pregnancy.
Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 6 Low birthweight (< 2500 g).
Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 7 Preterm births.
Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 8 Mean birthweight.
Comparison 7 Smoking cessation interventions: feedback vs usual care, Outcome 9 Stillbirths.
Comparison 8 Smoking cessation interventions: feedback vs less intensive intervention, Outcome 1 Abstinence in late pregnancy.
Comparison 8 Smoking cessation interventions: feedback vs less intensive intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 1 Abstinence in late pregnancy.
Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 2 Abstinence in late pregnancy:biochemically validated only.
Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 3 Abstinence at 0 to 5 months postpartum.
Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 4 Abstinence at 6 to 11 months postpartum.
Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 5 Reduction in late pregnancy: biochemically validated.
Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 6 Biochemical measures in late pregnancy: mean cotinine.
Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 7 Mean cigarettes per day in late pregnancy.
Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 8 Low birthweight.
Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 9 Preterm births.
Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 10 Mean birthweight.
Comparison 9 Smoking cessation interventions: incentives vs usual care, Outcome 11 NICU admissions.
Comparison 10 Smoking cessation interventions: incentives vs less intensive intervention, Outcome 1 Abstinence in late pregnancy.
Comparison 10 Smoking cessation interventions: incentives vs less intensive intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 10 Smoking cessation interventions: incentives vs less intensive intervention, Outcome 3 Abstinence at 0 to 5 months postpartum.
Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 1 Abstinence in late pregnancy.
Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 2 Abstinence in late pregnancy: biochemicaly validated only.
Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 3 Abstinence at 0 to 5 months postpartum.
Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 4 Abstinence at 6 to 11 months postpartum.
Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 5 Smoking reduction: numbers of women reducing smoking in late pregnancy (biochemically validated).
Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 6 Low birthweight (under 2500 g).
Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 7 Preterm birth (under 37 weeks).
Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 8 Mean birthweight.
Comparison 11 Smoking cessation interventions: incentives vs alternative intervention, Outcome 9 NICU admissions.
Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 1 Abstinence in late pregnancy.
Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 3 Continued abstinence (relapse prevention) in late pregnancy.
Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 4 Abstinence at 0 to 5 months postpartum.
Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 5 Abstinence at 6 to 11 months postpartum.
Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 6 Abstinence at 12 to 17 months postpartum.
Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 7 Smoking reduction: self reported > 50% reduction.
Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 8 Low birthweight (< 2500 g).
Comparison 12 Smoking cessation interventions: social support vs less intensive intervention, Outcome 9 Mean birthweight.
Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 1 Abstinence in late pregnancy.
Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 3 Abstinence at 6 to 11 months postpartum.
Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 4 Low birthweight.
Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 5 Preterm births.
Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 6 Mean birthweight.
Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 7 Stillbirths.
Comparison 13 Smoking cessation interventions: exercise vs usual care, Outcome 8 Neonatal deaths.
Comparison 14 Smoking cessation interventions: other vs usual care, Outcome 1 Abstinence in late pregnancy.
Comparison 14 Smoking cessation interventions: other vs usual care, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 15 Maternal health intervention with smoking cessation component: counselling vs usual care, Outcome 1 Abstinence in late pregnancy.
Comparison 15 Maternal health intervention with smoking cessation component: counselling vs usual care, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 15 Maternal health intervention with smoking cessation component: counselling vs usual care, Outcome 3 Abstinence at 0 to 5 months postpartum.
Comparison 15 Maternal health intervention with smoking cessation component: counselling vs usual care, Outcome 4 Smoking reduction: biochemical measures in late pregnancy.
Comparison 16 Maternal health intervention with smoking cessation component: health education vs less intensive intervention, Outcome 1 Abstinence in late pregnancy: biochemically validated only.
Comparison 16 Maternal health intervention with smoking cessation component: health education vs less intensive intervention, Outcome 2 Abstinence at 0 to 5 months postpartum.
Comparison 17 Maternal health intervention with smoking cessation component: feedback vs usual care, Outcome 1 Smoking abstinence in late pregnancy.
Comparison 17 Maternal health intervention with smoking cessation component: feedback vs usual care, Outcome 2 Smoking reduction in late pregnancy: self‐reported (various definitions).
Comparison 17 Maternal health intervention with smoking cessation component: feedback vs usual care, Outcome 3 Smoking reduction: self‐reported mean cigarettes per day measured in late pregnancy or at delivery.
Comparison 18 Maternal health intervention with smoking cessation component: social support vs usual care, Outcome 1 Abstinence in late pregnancy.
Comparison 18 Maternal health intervention with smoking cessation component: social support vs usual care, Outcome 2 Abstinence in late pregnancy:biochemically validated only.
Comparison 18 Maternal health intervention with smoking cessation component: social support vs usual care, Outcome 3 Abstinence at 0 to 5 months postpartum.
Comparison 18 Maternal health intervention with smoking cessation component: social support vs usual care, Outcome 4 Abstinence at 18 + months postpartum.
Comparison 18 Maternal health intervention with smoking cessation component: social support vs usual care, Outcome 5 Smoking reduction: mean cigarettes per day.
Comparison 19 Maternal health intervention with smoking cessation component: social support vs less intensive intervention, Outcome 1 Abstinence in late pregnancy.
Comparison 19 Maternal health intervention with smoking cessation component: social support vs less intensive intervention, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 19 Maternal health intervention with smoking cessation component: social support vs less intensive intervention, Outcome 3 Abstinence at 0 to 5 months postpartum.
Comparison 19 Maternal health intervention with smoking cessation component: social support vs less intensive intervention, Outcome 4 Smoking reduction: self reported mean cigarettes per day.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 1 Abstinence in late pregnancy: self‐reported and biochemically validated.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 2 Abstinence in late pregnancy: biochemically validated only.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 3 Continued abstinence (Relapse prevention) in late pregnancy for spontaneous quitters.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 4 Abstinence at 0 to 5 months postpartum.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 5 Abstinence at 6 to 11 months postpartum.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 6 Abstinence at 12 to 17 months postpartum.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 7 Abstinence at 18+ months postpartum.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 8 Smoking reduction: numbers of women reducing smoking in late pregnancy.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 9 Smoking reduction: biochemical measures in late pregnancy.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 10 Smoking reduction: self‐reported mean cigarettes per day measured in late pregnancy or at delivery.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 11 Low birthweight (under 2500 g).
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 12 Very low birthweight (under 1500 g).
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 13 Preterm birth (under 37 weeks).
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 14 Mean birthweight (g).
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 15 Stillbirths.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 16 Perinatal deaths.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 17 Neonatal deaths.
Comparison 20 Interventions for smoking cessation in pregnancy versus control: subgrouped by main intervention strategy, Outcome 18 NICU admissions.
| Separate intervention comparisons for supporting women to stop smoking in pregnancy (comparisons 1‐19) | ||||||
| Patient or population: Pregnant women who smoke Comparison: Usual care unless other comparison indicated | ||||||
| Interventions and comparisons | Anticipated absolute effects* (95% CI) | Relative effect *these footnotes outline consistent findings | № of participants | Quality of the evidence | Comments (details of variations from main results) | |
| Risk with comparison | Risk with main intervention strategy | |||||
| Counselling vs usual care | Study population | RR 1.44 | 12,432 | ⊕⊕⊕⊕ | No clear effect when compared to an alternative counselling intervention (RR 1.15, 95% CI 0.86 to 1.53) or if 1 component of a broader maternal health intervention (RR 0.93, 95% CI 0.69 to 1.25) | |
| 9 per 100 2 | 13 per 100 | |||||
| Health education vs usual care | Study population | RR 1.59 | 629 | ⊕⊕⊕⊝ | ||
| 8 per 100 | 12 per 100 | |||||
| Feedback vs usual care | Study population | RR 4.39 | 355 | ⊕⊕⊕⊝ | No clear effect when compared to a less intensive (RR 1.29, 95% CI 0.75 to 2.20) or alternative intervention; or 1 component of broader maternal health intervention (RR 2.11 95% CI 0.98 to 4.57) | |
| 4 per 100 | 17 per 100 | |||||
| Incentives vs alternative interventions 7 | Study population | RR 2.36 | 212 | ⊕⊕⊕⊕ | ||
| 16 per 100 | 37 per 100 | |||||
| Social support vs less intensive interventions 9 | Study population | RR 1.21 | 781 | ⊕⊕⊕⊕ | ||
| 19 per 100 | 23 per 100 | |||||
| Exercise vs usual care | Study population | RR 1.20 | 785 | ⊕⊕⊕⊝ | ||
| 6 per 100 | 8 per 100 | |||||
| Other (active dissemination vs passive dissemination) | Study population | RR 1.63 | 194 | ⊕⊕⊕⊝ | ||
| 6 per 100 | 10 per 100 | |||||
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). | ||||||
| GRADE Working Group grades of evidence | ||||||
| 1 Not downgraded for moderate heterogeneity (49%) as while there was some inconsistency in the magnitude, most RRs favoured counselling. 2 All control group risks are mean values of control group among included studies. 3 While there was no clear difference from this primary result, effect sizes varied if results restricted to biochemically validated smoking cessation (RR 1.23, 95% CI 1.04 to 1.45) or compared to less intensive interventions (RR 1.25, 95% CI 1.07 to 1.47). 4 Downgraded as relatively small numbers and wide confidence intervals. 5 Also no clear effect when compared to a less intensive or alternative intervention, restricted to biochemically validated cessation, single/multiple subgroups, provided as 1 component of a broader maternal health intervention, or are provided as a technological intervention only. 6 Remains clear effect when restricted to single study with biochemically validated cessation 7 Effect not calculable in usual care comparison due to zero cell counts, and not pooled in less intensive comparison due to substantial heterogeneity (I2 = 84%) 8 Clear effect also seen in subset of 3 counselling interventions which included lottery tickets (RR 1.72, 95% CI 1.04 to 2.85). 9 No usual care comparisons for this intervention 10 Remains unclear when restricted to biochemically validated cessation, all subgroups, when partner intervention removed and when provided as part of a broader maternal health intervention. | ||||||
| Outcomes for all interventions for smoking cessation in pregnancy compared to all controls: subgrouped by main intervention strategy (comparison 20) | ||||||
| Patient or population: Pregnant women who smoke | ||||||
| Outcomes | Anticipated absolute effects* (95% CI) | Relative effect | № of participants | Quality of the evidence | Comments | |
| Risk with control | Risk with Interventions for smoking cessation in pregnancy | |||||
| Abstinence in late pregnancy: self‐reported and biochemically validated | Study population | RR 1.35 | 26,637 | ⊕⊕⊕⊝ | ||
| 12 per 100 2 | 16 per 100 | |||||
| Abstinence at 0 to 5 months postpartum | Study population | RR 1.32 | 8366 | ⊕⊕⊕⊕ | ||
| 131 per 1000 | 173 per 1000 | |||||
| Low birthweight (under 2500 g) | Study population | RR 0.83 | 9402 | ⊕⊕⊕⊕ | ||
| 92 per 1000 | 76 per 1000 | |||||
| Preterm birth (under 37 weeks) | Study population | RR 0.93 | 9222 | ⊕⊕⊕⊕ | ||
| 72 per 1000 | 67 per 1000 | |||||
| Mean birthweight (g) | The mean birthweight (g) was 0 | MD 55.60 higher | 11,338 | ⊕⊕⊕⊕ | ||
| Stillbirths | Study population | RR 1.20 | 6170 | ⊕⊕⊕⊕ | ||
| 11 per 1000 | 13 per 1000 | |||||
| NICU admissions | Study population | RR 0.78 | 2100 | ⊕⊕⊕⊕ | ||
| 118 per 1000 | 92 per 1000 | |||||
| Adverse events and psychological impact | There did not appear to be any adverse effects from the psychosocial interventions. While there were mixed views from women about components of some interventions, 5 of 13 trials evaluating psychological impact measured an improvement in women's psychological well‐being and none reported a negative impact. | ‐ | (13 RCTs) | ⊕⊕⊕⊕ | ||
| *The risk in the intervention group (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). | ||||||
| GRADE Working Group grades of evidence | ||||||
| 1 Moderate heterogeneity (44%): refer to intervention comparisons for more consistent effect estimates 2 All control group risks are mean values of control group among included studies 3 No clear difference seen in meta‐regression analysis among women with low socio‐economic or ethnic minority status, interventions provided by routine care staff, comparison group, intervention intensity (frequency and duration), newly included studies, use of self‐help manuals or telephone support, or risk of bias. Evidence of differences with unclear implementation and unequal baseline characteristics. | ||||||
| Explanatory variable | k (n)1 | RR2 | (95% CI) | RoRR3 | (95% CI) | P value | Adjusted R2 %4 | I2 % (Res)5 | Overall model P value6 |
| 1.2.1a Main intervention strategy | 10% | 41% | 0.113 | ||||||
| Counselling (reference) | 51 (18,267) | 1.31 | (1.16, 1.48) | 1.00 | |||||
| Health education | 11 (2142) | 1.26 | (0.94, 1.69) | 0.96 | (0.70, 1.32) | 0.813 | |||
| Feedback | 6 (859) | 1.91 | (1.22, 3.00) | 1.46 | (0.91, 2.33) | 0.111 | |||
| Incentives | 12 (1708) | 1.84 | (1.34, 2.53) | 1.41 | (1.00, 1.98) | 0.051 | |||
| Social Support | 13 (2488) | 1.19 | (0.94, 1.50) | 0.91 | (0.69, 1.18) | 0.459 | |||
| 1.2.1b Focus of the intervention | 5% | 40% | 0.041 | ||||||
| Mental Health (reference) | 10 (2411) | 1.07 | (0.85, 1.36) | 1.00 | |||||
| Smoking cessation | 84 (23,847) | 1.40 | (1.27, 1.55) | 1.30 | (1.01, 1.68) | 0.041 | |||
| 1.2.2 Comparison type | ‐9% | 44% | 0.421 | ||||||
| Usual care (reference) | 46 (15,782) | 1.41 | (1.22, 1.62) | 1.00 | |||||
| Alternative intervention | 6 (500) | 1.62 | (1.06, 2.48) | 1.16 | (0.74, 1.81) | 0.522 | |||
| Less intensive | 43 (10,170) | 1.27 | (1.11, 1.46) | 0.91 | (0.74, 1.11) | 0.329 | |||
| 1.2.3a Intensity: frequency of contact | ‐1% | 42% | 0.184 | ||||||
| Single contact at time of routine pregnancy care (reference) | 8 (1422) | 1.90 | (1.24, 2.89) | 1.00 | |||||
| Single contact, outside of routine pregnancy care | 15 (5010) | 1.11 | (0.86, 1.43) | 0.59 | (0.36, 0.96) | 0.033 | |||
| 2‐5 contacts at time of care | 8 (2811) | 1.73 | (1.21, 2.48) | 0.91 | (0.52, 1.59) | 0.742 | |||
| 2‐5 contact outside routine care | 18 (6338) | 1.23 | (1.01, 1.51) | 0.65 | (0.41, 1.04) | 0.071 | |||
| > 5 contact at time of care | 10 (2081) | 1.36 | (1.00, 1.84) | 0.72 | (0.43, 1.20) | 0.206 | |||
| > 5 contact outside of care | 35 (8596) | 1.38 | (1.19, 1.60) | 0.73 | (0.47, 1.14) | 0.164 | |||
| 1.2.3b Intensity: duration of contact | ‐3% | 37% | 0.155 | ||||||
| < 15 mins (reference) | 8 (1422) | 1.26 | (1.00, 1.58) | 1.00 | |||||
| 15 ‐ 44 mins | 15 (5010) | 1.53 | (1.22, 1.93) | 1.22 | (0.88, 1.68) | 0.229 | |||
| 45 mins ‐ < 2 hrs | 8 (2811) | 1.27 | (1.05, 1.53) | 1.01 | (0.75, 1.35) | 0.962 | |||
| 2 hrs ‐ < 5 hrs | 18 (6338) | 1.14 | (0.90, 1.44) | 0.91 | (0.66, 1.26) | 0.556 | |||
| 5 hrs ‐ < 8 hrs | 10 (2081) | 1.27 | (0.91, 1.77) | 1.01 | (0.67, 1.51) | 0.967 | |||
| ≥ 8 hrs | 35 (8596) | 1.74 | (1.36, 2.23) | 1.38 | (0.99, 1.93) | 0.058 | |||
| 1.2.4a Use of self‐help manuals | ‐1% | 39% | 0.341 | ||||||
| No (reference) | 54 (11,447) | 1.33 | (1.16, 1.52) | 1.00 | |||||
| Yes | 30 (11,202) | 1.48 | (1.25, 1.74) | 1.11 | (0.90, 1.37) | 0.341 | |||
| 1.2.4b Use of telephone support | ‐6% | 40% | 0.869 | ||||||
| No (reference) | 75 (21,928) | 1.36 | (1.22, 1.51) | 1.00 | |||||
| Yes | 20 (4524) | 1.33 | (1.09, 1.62) | 0.98 | (0.78, 1.23) | 0.869 | |||
| 1.2.5 Social economic status | |||||||||
| Not low (reference) | 29 (8417) | 1.39 | (1.19, 1.63) | 1.00 | ‐1% | 42% | 0.706 | ||
| Low | 63 (16,962) | 1.34 | (1.18, 1.52) | 0.96 | (0.78, 1.18) | 0.706 | |||
| 1.2.6 Newly included trials | |||||||||
| Trials in previous review (reference) | 82 (23,311) | 1.36 | (1.23, 1.51) | 1.00 | ‐4% | 42% | 0.563 | ||
| Trials in update | 13 (3141) | 1.26 | (0.99, 1.61) | 0.93 | (0.71, 1.21) | 0.563 | |||
| 1.2.7a Type of trial | |||||||||
| Efficacy (reference) | 62 (16,765) | 1.26 | (1.12, 1.41) | 1.00 | ‐11% | 44% | 0.135 | ||
| Effectiveness | 23 (7956) | 1.50 | (1.22, 1.83) | 1.19 | (0.95, 1.50) | 0.135 | |||
| 1.2.7b Explicit strategy for dissemination | |||||||||
| No (reference) | 91 (23,236) | 1.36 | (1.23, 1.50) | 1.00 | ‐2% | 43% | 0.429 | ||
| Yes | 4 (3216) | 1.16 | (0.78, 1.72) | 0.85 | (0.57, 1.28) | 0.429 | |||
| 1.2.7c Unit of randomisation | |||||||||
| Individual (reference) | 84 (20,930) | 1.35 | (1.22, 1.50) | 1.00 | ‐7% | 43% | 0.741 | ||
| Cluster: practitioner level | 4 (2416) | 1.23 | (0.88, 1.73) | 0.91 | (0.64, 1.30) | 0.597 | |||
| Cluster: service level | 7 (3106) | 1.51 | (1.00, 2.29) | 1.12 | (0.73, 1.71) | 0.598 | |||
| 1.2.8a Risk of bias: sequence generation | 2% | 40% | 0.108 | ||||||
| Low (reference) | 45 (11,211) | 1.27 | (1.10, 1.45) | 1.00 | |||||
| High | 3 (1544) | 2.21 | (1.32, 3.71) | 1.75 | (1.02, 2.98) | 0.041 | |||
| Unclear | 47 (13,697) | 1.38 | (1.21, 1.57) | 1.09 | (0.90, 1.32) | 0.379 | |||
| 1.2.8b Risk of bias: allocation concealment | 6% | 40% | 0.032 | ||||||
| Low (reference) | 20 (6551) | 1.26 | (1.06, 1.49) | 1.00 | |||||
| High | 12 (3489) | 2.01 | (1.46, 2.75) | 1.60 | (1.12, 2.29) | 0.011 | |||
| Unclear | 63 (16,412) | 1.31 | (1.17, 1.48) | 1.04 | (0.85, 1.29) | 0.678 | |||
| 1.2.8c Risk of bias: attrition | |||||||||
| Low (reference) | 42 (11,479) | 1.32 | (1.14, 1.54) | 1.00 | ‐6% | 43% | 0.926 | ||
| High | 14 (4060) | 1.39 | (1.09, 1.78) | 1.05 | (0.79, 1.41) | 0.714 | |||
| Unclear | 39 (10,913) | 1.36 | (1.18, 1.57) | 1.03 | (0.84, 1.27) | 0.787 | |||
| 1.2.8d Risk of bias: selective reporting | ‐4% | 42% | 0.369 | ||||||
| Low (reference) | 50 (10,272) | 1.43 | (1.24, 1.64) | 1.00 | |||||
| High | 7 (3230) | 1.47 | (1.09, 1.99) | 1.03 | (0.74, 1.44) | 0.863 | |||
| Unclear | 38 (12,950) | 1.25 | (1.09, 1.44) | 0.88 | (0.72, 1.07) | 0.200 | |||
| 1.2.8e Risk of detection bias: outcome type (biochemically validated versus self‐report) | |||||||||
| Low risk [biochemically validated] (reference) | 67 (17,890) | 1.38 | (1.23, 1.55) | ‐1% | 40% | 0.406 | |||
| High risk [self‐report] | 23 (5988) | 1.37 | (1.14, 1.64) | 0.99 | (0.80, 1.23) | 0.928 | |||
| Unclear risk | 5 (2574) | 1.12 | (0.84, 1.50)) | 0.81 | (0.59, 1.11) | 0.185 | |||
| 1.2.8f Risk of bias: blinding participants/personnel | |||||||||
| Low (reference) | 3 (175) | 1.94 | (0.86, 4.39) | 1.00 | 2% | 43% | 0.214 | ||
| High | 66 (20,764) | 1.40 | (1.25, 1.56) | 0.72 | (0.32, 1.64) | 0.431 | |||
| Unclear | 26 (5513) | 1.18 | (0.98, 1.43) | 0.61 | (0.26, 1.41) | 0.244 | |||
| 1.2.8g Risk of bias: blinding outcome assessors | ‐1% | 41% | 0.111 | ||||||
| Low (reference) | 15 (4915) | 1.18 | (0.98, 1.43) | 1.00 | |||||
| High | 0 (0) | ‐ | ‐ | ‐ | ‐ | ‐ | |||
| Unclear | 80 (21,537) | 1.41 | (1.26, 1.57) | 1.19 | (0.96, 1.49) | 0.111 | |||
| 1.2.8h Risk of bias: baseline imbalance | |||||||||
| Low (reference) | 52 (15,295) | 1.33 | (1.18, 1.50) | 1.00 | 3% | 40% | 0.043 | ||
| High | 13 (4101) | 1.09 | (0.86, 1.38) | 0.82 | (0.63, 1.07) | 0.138 | |||
| Unclear | 30 (7056) | 1.61 | (1.32, 1.95) | 1.21 | (0.96, 1.52) | 0.101 | |||
| 1.2.8i Risk of bias: contamination | |||||||||
| Low (reference) | 75 (19,003) | 1.36 | (1.22, 1.52) | 1.00 | ‐4% | 43% | 0.723 | ||
| High | 14 (4266) | 1.24 | (0.98, 1.58) | 0.91 | (0.70, 1.19) | 0.490 | |||
| Unclear | 6 (3183) | 1.46 | (0.99, 2.14) | 1.07 | (0.71, 1.60) | 0.737 | |||
| 1.2.9 Program fidelity | 69% | 23% | < 0.001 | ||||||
| High (good) fidelity (reference) | 27 (8154) | 1.26 | (1.10, 1.44) | 1.00 | |||||
| Low (poor) fidelity | 37 (12,770) | 1.12 | (0.99, 1.26) | 0.89 | (0.74, 1.07) | 0.206 | |||
| Unclear fidelity | 31 (5528) | 1.79 | (1.52, 2.10) | 1.42 | (1.15, 1.75) | 0.001 | |||
| Study ID | Main findings | Rationale for not including outcomes in meta‐analysis |
| There was no statistically significant difference in smoking status among those who received either type of media or nurse counselling. | Results could not be included as smoking cessation rates were not reported by intervention group. | |
| There was no decrease in the rate of low birthweight for women who received the intervention. | Smoking outcomes were not reported. Birthweight outcomes were not included in this review, as aspects other than the smoking component of the intervention may have had an effect on birthweight, and it is unclear how many smokers were in each group, or what proportion quit. | |
| There was no significant difference in smoking between the intervention (motivational enhancement therapy) and control groups on self‐reported cigarettes per day, mean carbon monoxide or mean cotinine. | Study reports actual outcome data for movement in stages of change only. Outcome data for smoking cessation, cigarettes per day, carbon monoxide and cotinine levels are not reported. | |
| Significantly more women were able to quit smoking when enrolled in the intervention. | Actual cessation rates not reported (poster abstract only available). | |
| There was no difference between intervention and control groups in mean delta stage of change or 12‐month rate of maintained cessation in pregnant women (‐0.62 vs ‐0.65). | Data from intervention and control. Outcomes were combined for intervention and control groups in pregnant women. Unable to extract numbers. | |
| There was no significant difference in the number of mothers who smoked and quit smoking postpartum (0–24 months): Intervention group 16/42 (38%) vs control 11/31 (36%), OR 0.89 (95% CI 0.34 to 2.34) P = 0.82. | Self‐reported continuous abstinence 0‐24 months (18 + months postpartum)* Household always smoke‐free (0‐24 months) other outcomes not reported by smoking status. | |
| Urinary nicotine was found to decrease by 190 ng/mL in the intervention group (from 443 ng/mL to 253 ng/mL, P = 0.05), while urinary cotinine by 140 ng/mL (from 452 ng/mL to 312 ng/mL, P = 0.016) among intervention group participants. On the contrary, among control group participants urinary nicotine and cotinine concentrations were not found to decrease (cotinine: from 561 ng/mL to 737 ng/mL, P = 0.551 and nicotine: 891 ng/mL to 1040 ng/mL, P = 0.423). Comparing the 2 metabolites (nicotine vs cotinine), the latter was found to be associated statistically stronger with smoking cessation. Resuts were unable to be included as numbers in each study arm were not reported. | No results paper published yet, just protocol and abstract. No response from 2 emails sent to authors. | |
| At 1 month, 65% of behaviourally‐based intervention hospitals agreed to provide materials about smoking cessation, compared to 3% control hospitals. After 1 year, 43% intervention hospitals still provided materials, compared to 9% of control hospitals. McNemar’s Chi2 indicates a statistically meaningful difference between the proportion of intervention hospitals implementing the program and the proportion of control hospitals implementing the program (2 1 = 12, P = 0.0005). | Implementation data only included. No smoking cessation data provided. | |
| Compared to controls, smokers attending family planning, prenatal and well‐child clinics, exposed to the intervention were more likely to have quit (14.5% vs 7.7%). | It was not possible to separate out which data were related to pregnant women, as opposed to women recruited from family planning and well‐child clinics. Further, it was not clear at what stage in pregnancy women were recruited and what the postpartum time points were. | |
| Multimodal intervention to address smoking, stress and diet. However authors state there was insufficient data to analyse smoking trends so overall assessment of 'risks' were reported as follows: "Women in the treatment group reported significantly fewer risks than those in usual care at 1 month (.85 vs 1.20, OR .70) and 4 months postpartum (.72 vs .91, OR .81)." | Smoking outcomes not reported as authors state numbers were too small. | |
| Nurse‐visited mothers had greater reductions in cotinine (259 vs 12.32 ng/mL). | Only mean reduction in cotinine reported. | |
| In the components of this dissemination intervention which were randomised: "B) In practices that were assessed with a questionnaire, the provision of counselling improved partially compared to controls; C) The provision of counselling did not differ between practices that were visited and their controls." | No smoking outcomes reported. Only provision of smoking cessation services by providers. | |
| Smoking cessation outcomes were not reported for this exercise intervention. Abstract reports "Exercise (EC) significantly (P < 0.05) reduced cravings (ή2 = 0.46) compared with the passive control (PC), across time. Nonsignificant, but nevertheless, large effects were evident favouring the EC over time for TWS restlessness (ή2 = 0.34), stress (ή2 = 0.24), irritability (ή2 = 0.21), tension (ή2 = 0.15), and depression (ή2 = 0.14)." | No smoking cessation outcomes reported. Primary outcomes were cigarette cravings and tobacco withdrawal symptoms. | |
| There was no significant difference in LBW were 10.9% in the intervention group and 14.0% in controls (RR 0.75, 95% CI 0.55 to 1.03). Preterm births rates were 9.7 in the intervention group and 11.0 in the controls (RR 0.87, 95% CI 0.62 to 1.22). | Smoking outcomes were not reported. Birthweight and preterm birth outcomes were not included in this review, as aspects other than the smoking component of the intervention may have had an effect on birthweight and preterm births. | |
| CI: confidence interval | ||
| Comparison type | Total | ||||
| Usual care | Less intensive intervention | Alternative intervention | |||
| Main intervention strategy | Counselling | 32 | 18 | 1 | 51 |
| Health education | 5 | 5 | 1 | 11 | |
| Feedback | 2 | 4 | 0 | 6 | |
| Incentives | 5 | 4 | 4 | 13 | |
| Social support | 4 | 10 | 0 | 14 | |
| Exercise | 0 | 1 | 0 | 1 | |
| Other (Diss) | 0 | 1 | 0 | 1 | |
| Total | 48 | 43 | 6 | 97 | |
| This includes specific smoking cessation strategies and broader maternal health interventions with a smoking cessation component (C = 2, F = 1, I = 1, SS = 7) | |||||
| Group | Mean ES | ‐95% CI | +95% CI | P | N |
| 1 | 1.89 | 1.24 | 2.89 | .03 | 8 |
| 2 | 1.11 | 0.86 | 1.43 | .41 | 15 |
| 3 | 1.73 | 0.21 | 22.48 | .003 | 8 |
| 4 | 1.23 | 1.01 | 1.51 | .04 | 18 |
| 5 | 1.36 | 1.00 | 1.84 | .05 | 10 |
| 6 | 1.38 | 1.19 | 1.60 | .00 | 37 |
| 1 = Single contact during/at time of routine pregnancy care visits (but not ‘usual care’) without strategies to quit; 2 = Single contact, outside of ‘routine’ pregnancy care with strategies to quit; 3 = 2‐5 contacts to sustain motivation to stop smoking provided during/at time of routine pregnancy care visits; 4 = 2‐5 contacts to sustain motivation to stop smoking provided outside of routine care; 5 = > 5 contacts to sustain motivation to stop smoking provided during/at time of routine care visits; 6 = > 5 contacts to sustain motivation to stop smoking provided outside of routine care. 1 study, Campbell 2006, was treated as missing from this analysis as the intervention frequency was unclear. | |||||
| Group | Mean ES | ‐95% CI | +95% CI | P | N |
| 1 | 1.25 | 1.00 | 1.58 | .05 | 20 |
| 2 | 1.53 | 1.22 | 1.93 | .00 | 20 |
| 3 | 1.27 | 1.05 | 1.54 | .02 | 20 |
| 4 | 1.14 | 0.90 | 1.44 | .27 | 17 |
| 5 | 1.27 | 0.91 | 1.77 | .16 | 7 |
| 6 | 1.74 | 1.35 | 2.23 | .00 | 12 |
| 1 = Less than 15 mins; 2 = 15‐44 mins; 3 = 24 mins to less than 2 hours; 4 = 2 hours to less than 5 hours; 5 = 5 hours to less than 8 hours; 6 = 8 or more hours. 1 study, Campbell 2006, was treated as missing from this analysis as the intervention duration was unclear. | |||||
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 30 | 12432 | Risk Ratio (M‐H, Random, 95% CI) | 1.44 [1.19, 1.73] |
| 1.1 Single interventions | 13 | 4565 | Risk Ratio (M‐H, Random, 95% CI) | 1.33 [1.01, 1.74] |
| 1.2 Multiple interventions | 11 | 4048 | Risk Ratio (M‐H, Random, 95% CI) | 1.42 [1.04, 1.93] |
| 1.3 Tailored interventions | 6 | 3819 | Risk Ratio (M‐H, Random, 95% CI) | 1.49 [1.01, 2.20] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 21 | 9703 | Risk Ratio (M‐H, Random, 95% CI) | 1.23 [1.04, 1.45] |
| 2.1 Single interventions | 9 | 3903 | Risk Ratio (M‐H, Random, 95% CI) | 1.12 [0.90, 1.41] |
| 2.2 Multiple interventions | 8 | 3823 | Risk Ratio (M‐H, Random, 95% CI) | 1.26 [0.92, 1.73] |
| 2.3 Tailored interventions | 4 | 1977 | Risk Ratio (M‐H, Random, 95% CI) | 1.42 [0.84, 2.41] |
| 3 Continued abstinence (relapse prevention) in late pregnancy for spontaneous quitters Show forest plot | 8 | 688 | Risk Ratio (M‐H, Random, 95% CI) | 1.06 [0.93, 1.21] |
| 3.1 Single interventions | 2 | 100 | Risk Ratio (M‐H, Random, 95% CI) | 1.00 [0.93, 1.07] |
| 3.2 Multiple interventions | 3 | 297 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.93, 1.26] |
| 3.3 Tailored interventions | 3 | 291 | Risk Ratio (M‐H, Random, 95% CI) | 1.19 [0.97, 1.46] |
| 4 Abstinence at 0 to 5 months postpartum Show forest plot | 11 | 2926 | Risk Ratio (M‐H, Random, 95% CI) | 1.59 [1.26, 2.01] |
| 4.1 Single interventions | 7 | 1924 | Risk Ratio (M‐H, Random, 95% CI) | 1.58 [1.21, 2.06] |
| 4.2 Multiple interventions | 3 | 635 | Risk Ratio (M‐H, Random, 95% CI) | 2.55 [1.17, 5.53] |
| 4.3 Tailored interventions | 1 | 367 | Risk Ratio (M‐H, Random, 95% CI) | 1.18 [0.62, 2.25] |
| 5 Abstinence at 6 to 11 months postpartum Show forest plot | 6 | 2458 | Risk Ratio (M‐H, Random, 95% CI) | 1.33 [1.00, 1.77] |
| 5.1 Single interventions | 3 | 1098 | Risk Ratio (M‐H, Random, 95% CI) | 1.36 [0.99, 1.86] |
| 5.2 Multiple interventions | 2 | 733 | Risk Ratio (M‐H, Random, 95% CI) | 1.69 [0.48, 5.96] |
| 5.3 Tailored interventions | 1 | 627 | Risk Ratio (M‐H, Random, 95% CI) | 0.99 [0.40, 2.46] |
| 6 Abstinence at 12 to 17 months postpartum Show forest plot | 2 | 431 | Risk Ratio (M‐H, Random, 95% CI) | 2.20 [1.23, 3.96] |
| 6.1 Single interventions | 2 | 431 | Risk Ratio (M‐H, Random, 95% CI) | 2.20 [1.23, 3.96] |
| 7 Abstinence at 18+ months postpartum Show forest plot | 3 | 798 | Risk Ratio (M‐H, Random, 95% CI) | 0.98 [0.50, 1.92] |
| 7.1 Single interventions | 1 | 239 | Risk Ratio (M‐H, Random, 95% CI) | 1.17 [0.31, 4.42] |
| 7.2 Multiple interventions | 2 | 559 | Risk Ratio (M‐H, Random, 95% CI) | 0.92 [0.43, 2.00] |
| 8 Reduction in late pregnancy: biochemically validated Show forest plot | 2 | 1002 | Risk Ratio (M‐H, Random, 95% CI) | 0.79 [0.49, 1.28] |
| 8.1 Single interventions | 1 | 756 | Risk Ratio (M‐H, Random, 95% CI) | 0.63 [0.34, 1.20] |
| 8.2 Multiple interventions | 1 | 246 | Risk Ratio (M‐H, Random, 95% CI) | 1.04 [0.51, 2.13] |
| 9 Reduction in late pregnancy: self reported (various definitions) Show forest plot | 5 | 839 | Risk Ratio (M‐H, Random, 95% CI) | 1.66 [1.27, 2.17] |
| 9.1 Single interventions | 2 | 323 | Risk Ratio (M‐H, Random, 95% CI) | 1.61 [1.06, 2.43] |
| 9.2 Multiple interventions | 3 | 516 | Risk Ratio (M‐H, Random, 95% CI) | 1.74 [1.17, 2.57] |
| 10 Biochemical measures in late pregnancy: mean cotinine Show forest plot | 6 | 1884 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.44 [‐0.76, ‐0.12] |
| 10.1 Single interventions | 4 | 1443 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.35 [‐0.69, ‐0.02] |
| 10.2 Multiple interventions | 2 | 441 | Std. Mean Difference (IV, Random, 95% CI) | ‐1.20 [‐3.64, 1.24] |
| 11 Mean cigarettes per day in late pregnancy Show forest plot | 11 | Std. Mean Difference (IV, Random, 95% CI) | Totals not selected | |
| 11.1 Single interventions | 7 | Std. Mean Difference (IV, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 11.2 Multiple interventions | 2 | Std. Mean Difference (IV, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 11.3 Tailored interventions | 2 | Std. Mean Difference (IV, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 12 NICU admissions Show forest plot | 2 | 1140 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.52, 1.29] |
| 12.1 Single interventions | 1 | 762 | Risk Ratio (M‐H, Random, 95% CI) | 0.71 [0.47, 1.07] |
| 12.2 Tailored interventions | 1 | 378 | Risk Ratio (M‐H, Random, 95% CI) | 1.17 [0.55, 2.46] |
| 13 Very low birthweight infants (< 1500 g) Show forest plot | 2 | 1666 | Risk Ratio (M‐H, Random, 95% CI) | 1.27 [0.60, 2.71] |
| 13.1 Single interventions | 1 | 731 | Risk Ratio (M‐H, Random, 95% CI) | 0.91 [0.32, 2.59] |
| 13.2 Tailored interventions | 1 | 935 | Risk Ratio (M‐H, Random, 95% CI) | 1.83 [0.62, 5.43] |
| 14 Preterm births Show forest plot | 5 | 2653 | Risk Ratio (M‐H, Random, 95% CI) | 0.90 [0.64, 1.27] |
| 14.1 Single interventions | 3 | 1571 | Risk Ratio (M‐H, Random, 95% CI) | 0.83 [0.60, 1.17] |
| 14.2 Tailored interventions | 2 | 1082 | Risk Ratio (M‐H, Random, 95% CI) | 1.13 [0.46, 2.80] |
| 15 Mean birthweight Show forest plot | 11 | 4925 | Mean Difference (IV, Random, 95% CI) | 40.27 [7.87, 72.66] |
| 15.1 Single interventions | 6 | 1995 | Mean Difference (IV, Random, 95% CI) | 52.87 [‐0.41, 106.15] |
| 15.2 Multiple interventions | 2 | 588 | Mean Difference (IV, Random, 95% CI) | 72.91 [‐89.12, 234.95] |
| 15.3 Tailored interventions | 3 | 2342 | Mean Difference (IV, Random, 95% CI) | 23.25 [‐52.12, 98.62] |
| 16 Perinatal deaths Show forest plot | 2 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 16.1 Single interventions | 1 | 130 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] |
| 16.2 Tailored interventions | 1 | 935 | Risk Ratio (M‐H, Random, 95% CI) | 1.10 [0.52, 2.31] |
| 17 Stillbirths Show forest plot | 4 | 2212 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.51, 2.30] |
| 17.1 Single interventions | 2 | 859 | Risk Ratio (M‐H, Random, 95% CI) | 2.58 [0.38, 17.48] |
| 17.2 Tailored interventions | 2 | 1353 | Risk Ratio (M‐H, Random, 95% CI) | 0.92 [0.41, 2.10] |
| 18 Neonatal deaths Show forest plot | 3 | 2095 | Risk Ratio (M‐H, Random, 95% CI) | 2.06 [0.61, 6.92] |
| 18.1 Single interventions | 1 | 762 | Risk Ratio (M‐H, Random, 95% CI) | 1.17 [0.07, 18.65] |
| 18.2 Tailored interventions | 2 | 1333 | Risk Ratio (M‐H, Random, 95% CI) | 2.35 [0.61, 9.07] |
| 19 Low birthweight infants (< 2500 g) Show forest plot | 6 | 3836 | Risk Ratio (M‐H, Random, 95% CI) | 0.87 [0.70, 1.08] |
| 19.1 Single interventions | 2 | 1460 | Risk Ratio (M‐H, Random, 95% CI) | 0.79 [0.56, 1.11] |
| 19.2 Multiple interventions | 1 | 414 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.45, 2.61] |
| 19.3 Tailored interventions | 3 | 1962 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.66, 1.32] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 18 | 5657 | Risk Ratio (M‐H, Random, 95% CI) | 1.25 [1.07, 1.47] |
| 1.1 Single interventions | 7 | 1145 | Risk Ratio (M‐H, Random, 95% CI) | 1.21 [0.82, 1.80] |
| 1.2 Multiple interventions | 10 | 4260 | Risk Ratio (M‐H, Random, 95% CI) | 1.24 [1.07, 1.44] |
| 1.3 Tailored interventions | 1 | 252 | Risk Ratio (M‐H, Random, 95% CI) | 2.39 [1.03, 5.56] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 15 | 4919 | Risk Ratio (M‐H, Random, 95% CI) | 1.31 [1.10, 1.56] |
| 2.1 Single interventions | 6 | 967 | Risk Ratio (M‐H, Random, 95% CI) | 1.37 [0.89, 2.12] |
| 2.2 Multiple interventions | 8 | 3700 | Risk Ratio (M‐H, Random, 95% CI) | 1.25 [1.06, 1.47] |
| 2.3 Tailored interventions | 1 | 252 | Risk Ratio (M‐H, Random, 95% CI) | 2.39 [1.03, 5.56] |
| 3 Continued abstinence (relapse prevention) in late pregnancy (spontaneous quitters) Show forest plot | 5 | 904 | Risk Ratio (M‐H, Random, 95% CI) | 1.06 [0.99, 1.13] |
| 3.1 Single interventions | 3 | 416 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.96, 1.15] |
| 3.2 Multiple interventions | 2 | 488 | Risk Ratio (M‐H, Random, 95% CI) | 1.06 [0.96, 1.17] |
| 4 Abstinence at 0 to 5 months postpartum Show forest plot | 8 | 2647 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.93, 1.43] |
| 4.1 Single interventions | 3 | 749 | Risk Ratio (M‐H, Random, 95% CI) | 1.07 [0.81, 1.42] |
| 4.2 Multiple interventions | 4 | 1646 | Risk Ratio (M‐H, Random, 95% CI) | 1.19 [0.99, 1.43] |
| 4.3 Tailored interventions | 1 | 252 | Risk Ratio (M‐H, Random, 95% CI) | 12.80 [1.70, 96.35] |
| 5 Abstinence at 6 to 11 months postpartum Show forest plot | 4 | 1661 | Risk Ratio (M‐H, Random, 95% CI) | 1.09 [0.91, 1.31] |
| 5.1 Single interventions | 2 | 495 | Risk Ratio (M‐H, Random, 95% CI) | 1.14 [0.84, 1.54] |
| 5.2 Multiple interventions | 2 | 1166 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.80, 1.38] |
| 6 Abstinence at 12 to 17 months postpartum Show forest plot | 3 | 1578 | Risk Ratio (M‐H, Random, 95% CI) | 1.11 [0.87, 1.41] |
| 6.1 Single interventions | 1 | 390 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.76, 1.52] |
| 6.2 Multiple interventions | 2 | 1188 | Risk Ratio (M‐H, Random, 95% CI) | 1.25 [0.71, 2.20] |
| 7 Reduction in late pregnancy: biochemically validated Show forest plot | 2 | 857 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [0.98, 1.87] |
| 7.1 Multiple interventions | 2 | 857 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [0.98, 1.87] |
| 8 Reduction in late pregnancy: self‐reported > 50% Show forest plot | 2 | 1235 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [1.07, 1.71] |
| 8.1 Multiple interventions | 2 | 1235 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [1.07, 1.71] |
| 9 Mean cigarettes per day in late pregnancy Show forest plot | 2 | 397 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.11 [‐0.30, 0.09] |
| 9.1 Single interventions | 1 | 121 | Std. Mean Difference (IV, Random, 95% CI) | 0.01 [‐0.34, 0.37] |
| 9.2 Multiple interventions | 1 | 276 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.16 [‐0.40, 0.08] |
| 10 Low birthweight infants (< 2500 g) Show forest plot | 2 | 503 | Risk Ratio (M‐H, Random, 95% CI) | 0.58 [0.32, 1.04] |
| 10.1 Single interventions | 1 | 227 | Risk Ratio (M‐H, Random, 95% CI) | 0.55 [0.25, 1.21] |
| 10.2 Multiple interventions | 1 | 276 | Risk Ratio (M‐H, Random, 95% CI) | 0.61 [0.25, 1.50] |
| 11 Preterm births Show forest plot | 3 | 794 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.47, 1.42] |
| 11.1 Single interventions | 1 | 227 | Risk Ratio (M‐H, Random, 95% CI) | 0.55 [0.25, 1.21] |
| 11.2 Multiple interventions | 1 | 308 | Risk Ratio (M‐H, Random, 95% CI) | 1.17 [0.46, 2.95] |
| 11.3 Tailored interventions | 1 | 259 | Risk Ratio (M‐H, Random, 95% CI) | 1.30 [0.30, 5.71] |
| 12 Mean birthweight Show forest plot | 3 | 546 | Mean Difference (IV, Random, 95% CI) | 56.02 [‐31.46, 143.50] |
| 12.1 Single interventions | 1 | 227 | Mean Difference (IV, Random, 95% CI) | 57.00 [‐93.50, 207.50] |
| 12.2 Multiple interventions | 2 | 319 | Mean Difference (IV, Random, 95% CI) | 76.01 [‐88.59, 240.61] |
| 13 Stillbirths Show forest plot | 1 | 242 | Risk Ratio (M‐H, Random, 95% CI) | 1.84 [0.17, 20.04] |
| 13.1 Single interventions | 1 | 242 | Risk Ratio (M‐H, Random, 95% CI) | 1.84 [0.17, 20.04] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.86, 1.53] |
| 1.1 Single interventions | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.86, 1.53] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.86, 1.53] |
| 2.1 Single interventions | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.86, 1.53] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.63, 1.76] |
| 3.1 Single interventions | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.63, 1.76] |
| 4 Abstinence at 6 to 11 months postpartum Show forest plot | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 0.76 [0.33, 1.73] |
| 4.1 Single interventions | 1 | 257 | Risk Ratio (M‐H, Random, 95% CI) | 0.76 [0.33, 1.73] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 5 | 629 | Risk Ratio (M‐H, Random, 95% CI) | 1.59 [0.99, 2.55] |
| 1.1 Single interventions | 4 | 484 | Risk Ratio (M‐H, Random, 95% CI) | 1.53 [0.93, 2.49] |
| 1.2 Multiple interventions | 1 | 145 | Risk Ratio (M‐H, Random, 95% CI) | 4.06 [0.46, 35.41] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 3 | 337 | Risk Ratio (M‐H, Random, 95% CI) | 1.45 [0.82, 2.58] |
| 2.1 Single interventions | 3 | 337 | Risk Ratio (M‐H, Random, 95% CI) | 1.45 [0.82, 2.58] |
| 3 Continued abstinence (Relapse prevention) in late pregnancy for spontaneous quitters Show forest plot | 1 | 70 | Risk Ratio (M‐H, Random, 95% CI) | 1.02 [0.86, 1.23] |
| 3.1 Single interventions | 1 | 70 | Risk Ratio (M‐H, Random, 95% CI) | 1.02 [0.86, 1.23] |
| 4 Abstinence at 0 to 5 months postpartum Show forest plot | 2 | 237 | Risk Ratio (M‐H, Random, 95% CI) | 3.56 [1.31, 9.67] |
| 4.1 Single interventions | 2 | 237 | Risk Ratio (M‐H, Random, 95% CI) | 3.56 [1.31, 9.67] |
| 5 Mean cigarettes per day in late pregnancy Show forest plot | 2 | 687 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.55 [‐0.94, ‐0.15] |
| 5.1 Single interventions | 1 | 552 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.72 [‐0.89, ‐0.55] |
| 5.2 Multiple interventions | 1 | 135 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.32 [‐0.66, 0.02] |
| 6 Low birth weight Show forest plot | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 1.10 [0.66, 1.84] |
| 6.1 Single interventions | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 1.10 [0.66, 1.84] |
| 7 Preterm births (< 37 weeks) Show forest plot | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 1.03 [0.53, 2.00] |
| 7.1 Single interventions | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 1.03 [0.53, 2.00] |
| 8 Mean birthweight Show forest plot | 1 | 552 | Mean Difference (IV, Fixed, 95% CI) | ‐12.0 [‐102.29, 78.29] |
| 8.1 Single interventions | 1 | 552 | Mean Difference (IV, Fixed, 95% CI) | ‐12.0 [‐102.29, 78.29] |
| 9 Perinatal deaths Show forest plot | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 4.40 [0.49, 39.08] |
| 9.1 Single interventions | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 4.40 [0.49, 39.08] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 4 | 1282 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.85, 1.70] |
| 1.1 Single interventions | 2 | 853 | Risk Ratio (M‐H, Random, 95% CI) | 1.41 [0.99, 2.01] |
| 1.2 Multiple interventions | 1 | 198 | Risk Ratio (M‐H, Random, 95% CI) | 1.59 [0.68, 3.73] |
| 1.3 Tailored interventions | 1 | 231 | Risk Ratio (M‐H, Random, 95% CI) | 0.74 [0.44, 1.26] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 3 | 1082 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.70, 1.91] |
| 2.1 Single interventions | 1 | 653 | Risk Ratio (M‐H, Random, 95% CI) | 1.46 [0.88, 2.43] |
| 2.2 Multiple interventions | 1 | 198 | Risk Ratio (M‐H, Random, 95% CI) | 1.59 [0.68, 3.73] |
| 2.3 Tailored interventions | 1 | 231 | Risk Ratio (M‐H, Random, 95% CI) | 0.74 [0.44, 1.26] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 2 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 3.1 Single interventions | 2 | 844 | Risk Ratio (M‐H, Random, 95% CI) | 1.55 [1.01, 2.36] |
| 4 Mean cigarettes per day in late pregnancy Show forest plot | 1 | 127 | Mean Difference (IV, Random, 95% CI) | ‐0.70 [‐3.37, 1.97] |
| 4.1 Tailored interventions | 1 | 127 | Mean Difference (IV, Random, 95% CI) | ‐0.70 [‐3.37, 1.97] |
| 5 Low birthweight (< 2500 g) Show forest plot | 1 | 620 | Risk Ratio (M‐H, Random, 95% CI) | 0.60 [0.28, 1.29] |
| 5.1 Single interventions | 1 | 620 | Risk Ratio (M‐H, Random, 95% CI) | 0.60 [0.28, 1.29] |
| 6 Preterm births Show forest plot | 1 | 618 | Risk Ratio (M‐H, Random, 95% CI) | 0.76 [0.32, 1.80] |
| 6.1 Single interventions | 1 | 618 | Risk Ratio (M‐H, Random, 95% CI) | 0.76 [0.32, 1.80] |
| 7 Mean birthweight Show forest plot | 1 | 620 | Mean Difference (IV, Fixed, 95% CI) | 71.0 [‐26.58, 168.58] |
| 7.1 Single interventions | 1 | 620 | Mean Difference (IV, Fixed, 95% CI) | 71.0 [‐26.58, 168.58] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 1 | 31 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [0.19, 18.60] |
| 1.1 Single interventions | 1 | 31 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [0.19, 18.60] |
| 2 Abstinence in late pregnancy: biochemically validated Show forest plot | 1 | 31 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [0.19, 18.60] |
| 2.1 Single interventions | 1 | 31 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [0.19, 18.60] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 2 | 355 | Risk Ratio (M‐H, Random, 95% CI) | 4.39 [1.89, 10.21] |
| 1.1 Multiple interventions | 2 | 355 | Risk Ratio (M‐H, Random, 95% CI) | 4.39 [1.89, 10.21] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 1 | 244 | Risk Ratio (M‐H, Random, 95% CI) | 3.88 [1.38, 10.93] |
| 2.1 Multiple interventions | 1 | 244 | Risk Ratio (M‐H, Random, 95% CI) | 3.88 [1.38, 10.93] |
| 3 Reduction in late pregnancy: biochemically validated Show forest plot | 1 | 244 | Risk Ratio (M‐H, Random, 95% CI) | 1.48 [0.93, 2.37] |
| 3.1 Multiple interventions | 1 | 244 | Risk Ratio (M‐H, Random, 95% CI) | 1.48 [0.93, 2.37] |
| 4 Reduction in late pregnancy: self‐reported (various definitions) Show forest plot | 1 | 111 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [1.24, 2.84] |
| 4.1 Multiple interventions | 1 | 111 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [1.24, 2.84] |
| 5 Mean cigarettes per day in late pregnancy Show forest plot | 1 | 104 | Mean Difference (IV, Random, 95% CI) | ‐3.0 [‐4.68, ‐1.32] |
| 5.1 Multiple interventions | 1 | 104 | Mean Difference (IV, Random, 95% CI) | ‐3.0 [‐4.68, ‐1.32] |
| 6 Low birthweight (< 2500 g) Show forest plot | 1 | 2848 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.63, 1.06] |
| 6.1 Multiple interventions | 1 | 2848 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.63, 1.06] |
| 7 Preterm births Show forest plot | 2 | 3111 | Risk Ratio (M‐H, Random, 95% CI) | 0.60 [0.28, 1.29] |
| 7.1 Multiple interventions | 2 | 3111 | Risk Ratio (M‐H, Random, 95% CI) | 0.60 [0.28, 1.29] |
| 8 Mean birthweight Show forest plot | 2 | 3006 | Mean Difference (IV, Random, 95% CI) | 79.43 [‐53.05, 211.91] |
| 8.1 Multiple interventions | 2 | 3006 | Mean Difference (IV, Random, 95% CI) | 79.43 [‐53.05, 211.91] |
| 9 Stillbirths Show forest plot | 2 | 2960 | Risk Ratio (M‐H, Random, 95% CI) | 1.28 [0.69, 2.39] |
| 9.1 Multiple interventions | 2 | 2960 | Risk Ratio (M‐H, Random, 95% CI) | 1.28 [0.69, 2.39] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 3 | 439 | Risk Ratio (M‐H, Random, 95% CI) | 1.29 [0.75, 2.20] |
| 1.1 Single interventions | 2 | 259 | Risk Ratio (M‐H, Random, 95% CI) | 1.06 [0.48, 2.36] |
| 1.2 Multiple interventions | 1 | 180 | Risk Ratio (M‐H, Random, 95% CI) | 1.57 [0.71, 3.47] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 3 | 439 | Risk Ratio (M‐H, Random, 95% CI) | 1.29 [0.75, 2.20] |
| 2.1 Single interventions | 2 | 259 | Risk Ratio (M‐H, Random, 95% CI) | 1.06 [0.48, 2.36] |
| 2.2 Multiple interventions | 1 | 180 | Risk Ratio (M‐H, Random, 95% CI) | 1.57 [0.71, 3.47] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 5 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 1.1 Single interventions | 3 | 731 | Risk Ratio (M‐H, Random, 95% CI) | 2.73 [1.72, 4.35] |
| 1.2 Multiple interventions | 1 | 41 | Risk Ratio (M‐H, Random, 95% CI) | 0.83 [0.17, 3.93] |
| 1.3 Tailored interventions | 1 | 41 | Risk Ratio (M‐H, Random, 95% CI) | 0.70 [0.13, 3.68] |
| 2 Abstinence in late pregnancy:biochemically validated only Show forest plot | 5 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 2.1 Single interventions | 3 | 731 | Risk Ratio (M‐H, Random, 95% CI) | 2.73 [1.72, 4.35] |
| 2.2 Multiple interventions | 1 | 41 | Risk Ratio (M‐H, Random, 95% CI) | 0.83 [0.17, 3.93] |
| 2.3 Tailored interventions | 1 | 41 | Risk Ratio (M‐H, Random, 95% CI) | 0.70 [0.13, 3.68] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 2 | 150 | Risk Ratio (M‐H, Random, 95% CI) | 1.09 [0.56, 2.13] |
| 3.1 Multiple interventions | 2 | 150 | Risk Ratio (M‐H, Random, 95% CI) | 1.09 [0.56, 2.13] |
| 4 Abstinence at 6 to 11 months postpartum Show forest plot | 1 | 609 | Risk Ratio (M‐H, Random, 95% CI) | 3.88 [2.10, 7.16] |
| 4.1 Single interventions | 1 | 609 | Risk Ratio (M‐H, Random, 95% CI) | 3.88 [2.10, 7.16] |
| 5 Reduction in late pregnancy: biochemically validated Show forest plot | 2 | Risk Ratio (M‐H, Random, 95% CI) | Totals not selected | |
| 5.1 Single interventions | 2 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 6 Biochemical measures in late pregnancy: mean cotinine Show forest plot | 2 | 102 | Mean Difference (IV, Random, 95% CI) | ‐2.00 [‐6.61, 2.60] |
| 6.1 Single interventions | 2 | 102 | Mean Difference (IV, Random, 95% CI) | ‐2.00 [‐6.61, 2.60] |
| 7 Mean cigarettes per day in late pregnancy Show forest plot | 1 | 74 | Mean Difference (IV, Random, 95% CI) | ‐8.2 [‐10.83, ‐5.57] |
| 7.1 Single interventions | 1 | 74 | Mean Difference (IV, Random, 95% CI) | ‐8.2 [‐10.83, ‐5.57] |
| 8 Low birthweight Show forest plot | 4 | 215 | Risk Ratio (M‐H, Random, 95% CI) | 0.70 [0.40, 1.23] |
| 8.1 Single interventions | 2 | 68 | Risk Ratio (M‐H, Random, 95% CI) | 0.64 [0.32, 1.28] |
| 8.2 Multiple interventions | 2 | 147 | Risk Ratio (M‐H, Random, 95% CI) | 0.84 [0.32, 2.21] |
| 9 Preterm births Show forest plot | 5 | 753 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.73, 1.82] |
| 9.1 Single interventions | 3 | 606 | Risk Ratio (M‐H, Random, 95% CI) | 1.30 [0.77, 2.18] |
| 9.2 Multiple interventions | 2 | 147 | Risk Ratio (M‐H, Random, 95% CI) | 0.61 [0.21, 1.77] |
| 10 Mean birthweight Show forest plot | 5 | 797 | Mean Difference (IV, Random, 95% CI) | 109.38 [60.51, 158.26] |
| 10.1 Single interventions | 3 | 650 | Mean Difference (IV, Random, 95% CI) | 41.69 [‐50.96, 134.33] |
| 10.2 Multiple interventions | 2 | 147 | Mean Difference (IV, Random, 95% CI) | 126.49 [67.80, 185.19] |
| 11 NICU admissions Show forest plot | 2 | 68 | Risk Ratio (M‐H, Random, 95% CI) | 0.80 [0.51, 1.26] |
| 11.1 Single interventions | 2 | 68 | Risk Ratio (M‐H, Random, 95% CI) | 0.80 [0.51, 1.26] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 4 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 1.1 Single interventions | 3 | 731 | Risk Ratio (M‐H, Random, 95% CI) | 0.81 [0.59, 1.12] |
| 1.2 Multiple interventions | 1 | 220 | Risk Ratio (M‐H, Random, 95% CI) | 3.64 [1.84, 7.23] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 4 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 2.1 Single interventions | 3 | 731 | Risk Ratio (M‐H, Random, 95% CI) | 0.81 [0.59, 1.12] |
| 2.2 Multiple interventions | 1 | 220 | Risk Ratio (M‐H, Random, 95% CI) | 3.64 [1.84, 7.23] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 1 | 205 | Risk Ratio (M‐H, Random, 95% CI) | 3.63 [1.54, 8.58] |
| 3.1 Multiple interventions | 1 | 205 | Risk Ratio (M‐H, Random, 95% CI) | 3.63 [1.54, 8.58] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 4 | 212 | Risk Ratio (M‐H, Random, 95% CI) | 2.36 [1.36, 4.09] |
| 1.1 Single interventions | 2 | 94 | Risk Ratio (M‐H, Random, 95% CI) | 2.19 [0.53, 9.04] |
| 1.2 Multiple interventions | 2 | 118 | Risk Ratio (M‐H, Random, 95% CI) | 2.20 [1.06, 4.55] |
| 2 Abstinence in late pregnancy: biochemicaly validated only Show forest plot | 4 | 212 | Risk Ratio (M‐H, Random, 95% CI) | 2.36 [1.36, 4.09] |
| 2.1 Single interventions | 2 | 94 | Risk Ratio (M‐H, Random, 95% CI) | 2.19 [0.53, 9.04] |
| 2.2 Multiple interventions | 2 | 118 | Risk Ratio (M‐H, Random, 95% CI) | 2.20 [1.06, 4.55] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 3 | 195 | Risk Ratio (M‐H, Random, 95% CI) | 1.79 [0.57, 5.61] |
| 3.1 Single interventions | 1 | 77 | Risk Ratio (M‐H, Random, 95% CI) | 9.73 [1.29, 73.13] |
| 3.2 Multiple interventions | 2 | 118 | Risk Ratio (M‐H, Random, 95% CI) | 1.13 [0.51, 2.52] |
| 4 Abstinence at 6 to 11 months postpartum Show forest plot | 3 | 195 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.85, 1.01] |
| 4.1 Single interventions | 1 | 77 | Risk Ratio (M‐H, Random, 95% CI) | 0.94 [0.85, 1.05] |
| 4.2 Multiple interventions | 2 | 118 | Risk Ratio (M‐H, Random, 95% CI) | 0.90 [0.79, 1.03] |
| 5 Smoking reduction: numbers of women reducing smoking in late pregnancy (biochemically validated) Show forest plot | 1 | 17 | Risk Ratio (M‐H, Random, 95% CI) | 0.71 [0.18, 2.88] |
| 5.1 Single interventions | 1 | 17 | Risk Ratio (M‐H, Random, 95% CI) | 0.71 [0.18, 2.88] |
| 6 Low birthweight (under 2500 g) Show forest plot | 3 | 184 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.60 [0.26, 1.40] |
| 6.1 Single interventions | 1 | 73 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.43 [0.12, 1.49] |
| 6.2 Multiple interventions | 2 | 111 | Risk Ratio (M‐H, Fixed, 95% CI) | 0.84 [0.26, 2.69] |
| 7 Preterm birth (under 37 weeks) Show forest plot | 3 | 184 | Risk Ratio (M‐H, Random, 95% CI) | 0.48 [0.20, 1.14] |
| 7.1 Single interventions | 1 | 73 | Risk Ratio (M‐H, Random, 95% CI) | 0.38 [0.11, 1.30] |
| 7.2 Multiple interventions | 2 | 111 | Risk Ratio (M‐H, Random, 95% CI) | 0.60 [0.17, 2.12] |
| 8 Mean birthweight Show forest plot | 3 | 184 | Mean Difference (IV, Random, 95% CI) | 134.58 [76.32, 192.83] |
| 8.1 Single interventions | 1 | 73 | Mean Difference (IV, Random, 95% CI) | 253.0 [‐3.67, 509.67] |
| 8.2 Multiple interventions | 2 | 111 | Mean Difference (IV, Random, 95% CI) | 128.48 [65.86, 191.10] |
| 9 NICU admissions Show forest plot | 3 | 184 | Risk Ratio (M‐H, Random, 95% CI) | 0.64 [0.26, 1.55] |
| 9.1 Single interventions | 1 | 73 | Risk Ratio (M‐H, Random, 95% CI) | 0.76 [0.24, 2.49] |
| 9.2 Multiple interventions | 2 | 111 | Risk Ratio (M‐H, Random, 95% CI) | 0.49 [0.13, 1.95] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 7 | 781 | Risk Ratio (M‐H, Random, 95% CI) | 1.21 [0.93, 1.58] |
| 1.1 Single interventions | 2 | 224 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [0.57, 3.18] |
| 1.2 Multiple interventions | 4 | 406 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [0.83, 2.18] |
| 1.3 Tailored interventions | 1 | 151 | Risk Ratio (M‐H, Random, 95% CI) | 1.22 [0.59, 2.52] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 6 | 601 | Risk Ratio (M‐H, Random, 95% CI) | 1.42 [0.98, 2.07] |
| 2.1 Single interventions | 2 | 224 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [0.57, 3.18] |
| 2.2 Multiple interventions | 3 | 226 | Risk Ratio (M‐H, Random, 95% CI) | 1.93 [1.00, 3.74] |
| 2.3 Tailored interventions | 1 | 151 | Risk Ratio (M‐H, Random, 95% CI) | 1.22 [0.59, 2.52] |
| 3 Continued abstinence (relapse prevention) in late pregnancy Show forest plot | 1 | 211 | Risk Ratio (M‐H, Random, 95% CI) | 1.02 [0.89, 1.16] |
| 3.1 Multiple interventions | 1 | 211 | Risk Ratio (M‐H, Random, 95% CI) | 1.02 [0.89, 1.16] |
| 4 Abstinence at 0 to 5 months postpartum Show forest plot | 2 | 472 | Risk Ratio (M‐H, Random, 95% CI) | 1.34 [0.35, 5.14] |
| 4.1 Single interventions | 1 | 82 | Risk Ratio (M‐H, Random, 95% CI) | 5.8 [0.33, 101.27] |
| 4.2 Multiple interventions | 1 | 390 | Risk Ratio (M‐H, Random, 95% CI) | 0.98 [0.74, 1.31] |
| 5 Abstinence at 6 to 11 months postpartum Show forest plot | 3 | 533 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.81, 1.44] |
| 5.1 Multiple interventions | 3 | 533 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.81, 1.44] |
| 6 Abstinence at 12 to 17 months postpartum Show forest plot | 1 | 391 | Risk Ratio (M‐H, Random, 95% CI) | 1.07 [0.76, 1.51] |
| 6.1 Multiple interventions | 1 | 391 | Risk Ratio (M‐H, Random, 95% CI) | 1.07 [0.76, 1.51] |
| 7 Smoking reduction: self reported > 50% reduction Show forest plot | 1 | 151 | Risk Ratio (M‐H, Random, 95% CI) | 0.96 [0.64, 1.44] |
| 7.1 Tailored interventions | 1 | 151 | Risk Ratio (M‐H, Random, 95% CI) | 0.96 [0.64, 1.44] |
| 8 Low birthweight (< 2500 g) Show forest plot | 1 | 79 | Risk Ratio (M‐H, Random, 95% CI) | 1.00 [0.33, 2.99] |
| 8.1 Single interventions | 1 | 79 | Risk Ratio (M‐H, Random, 95% CI) | 1.00 [0.33, 2.99] |
| 9 Mean birthweight Show forest plot | 1 | 142 | Mean Difference (IV, Fixed, 95% CI) | 28.0 [‐152.48, 208.48] |
| 9.1 Single interventions | 1 | 142 | Mean Difference (IV, Fixed, 95% CI) | 28.0 [‐152.48, 208.48] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.72, 2.01] |
| 1.1 Single interventions | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.72, 2.01] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.72, 2.01] |
| 2.1 Single interventions | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.72, 2.01] |
| 3 Abstinence at 6 to 11 months postpartum Show forest plot | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.50 [0.81, 2.79] |
| 3.1 Single interventions | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.50 [0.81, 2.79] |
| 4 Low birthweight Show forest plot | 1 | 712 | Risk Ratio (M‐H, Random, 95% CI) | 0.88 [0.58, 1.32] |
| 4.1 Single interventions | 1 | 712 | Risk Ratio (M‐H, Random, 95% CI) | 0.88 [0.58, 1.32] |
| 5 Preterm births Show forest plot | 1 | 704 | Risk Ratio (M‐H, Random, 95% CI) | 1.32 [0.81, 2.14] |
| 5.1 Single interventions | 1 | 704 | Risk Ratio (M‐H, Random, 95% CI) | 1.32 [0.81, 2.14] |
| 6 Mean birthweight Show forest plot | 1 | 713 | Mean Difference (IV, Random, 95% CI) | ‐14.40 [‐104.15, 75.35] |
| 6.1 Single interventions | 1 | 713 | Mean Difference (IV, Random, 95% CI) | ‐14.40 [‐104.15, 75.35] |
| 7 Stillbirths Show forest plot | 1 | 756 | Risk Ratio (M‐H, Random, 95% CI) | 1.01 [0.14, 7.10] |
| 7.1 Single interventions | 1 | 756 | Risk Ratio (M‐H, Random, 95% CI) | 1.01 [0.14, 7.10] |
| 8 Neonatal deaths Show forest plot | 1 | 775 | Risk Ratio (M‐H, Random, 95% CI) | 0.34 [0.01, 8.31] |
| 8.1 Single interventions | 1 | 775 | Risk Ratio (M‐H, Random, 95% CI) | 0.34 [0.01, 8.31] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 1 | 194 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.62, 4.32] |
| 1.1 Single interventions | 1 | 194 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.62, 4.32] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 1 | 194 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.62, 4.32] |
| 2.1 Single interventions | 1 | 194 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.62, 4.32] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 2 | 258 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.69, 1.25] |
| 1.1 Single | 2 | 258 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.69, 1.25] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 1 | 198 | Risk Ratio (M‐H, Random, 95% CI) | 1.00 [0.72, 1.40] |
| 2.1 Single | 1 | 198 | Risk Ratio (M‐H, Random, 95% CI) | 1.00 [0.72, 1.40] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 1 | 198 | Risk Ratio (M‐H, Random, 95% CI) | 1.46 [0.97, 2.19] |
| 3.1 Single interventions | 1 | 198 | Risk Ratio (M‐H, Random, 95% CI) | 1.46 [0.97, 2.19] |
| 4 Smoking reduction: biochemical measures in late pregnancy Show forest plot | 1 | 198 | Std. Mean Difference (IV, Random, 95% CI) | 0.11 [‐0.17, 0.39] |
| 4.1 Mean cotinine | 1 | 198 | Std. Mean Difference (IV, Random, 95% CI) | 0.11 [‐0.17, 0.39] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy: biochemically validated only Show forest plot | 1 | 530 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.65, 1.32] |
| 1.1 Single interventions | 1 | 530 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.65, 1.32] |
| 2 Abstinence at 0 to 5 months postpartum Show forest plot | 1 | 530 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.67, 1.65] |
| 2.1 Single interventions | 1 | 530 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.67, 1.65] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Smoking abstinence in late pregnancy Show forest plot | 1 | 65 | Risk Ratio (M‐H, Random, 95% CI) | 2.11 [0.98, 4.57] |
| 1.1 Single interventions | 1 | 65 | Risk Ratio (M‐H, Random, 95% CI) | 2.11 [0.98, 4.57] |
| 2 Smoking reduction in late pregnancy: self‐reported (various definitions) Show forest plot | 1 | 65 | Risk Ratio (M‐H, Random, 95% CI) | 0.95 [0.42, 2.18] |
| 2.1 Single interventions | 1 | 65 | Risk Ratio (M‐H, Random, 95% CI) | 0.95 [0.42, 2.18] |
| 3 Smoking reduction: self‐reported mean cigarettes per day measured in late pregnancy or at delivery Show forest plot | 1 | 3571 | Mean Difference (IV, Random, 95% CI) | 1.5 [1.07, 1.93] |
| 3.1 Single interventions | 1 | 3571 | Mean Difference (IV, Random, 95% CI) | 1.5 [1.07, 1.93] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 4 | Risk Ratio (M‐H, Random, 95% CI) | Totals not selected | |
| 1.1 Single interventions | 2 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 1.2 Tailored interventions | 2 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 2 Abstinence in late pregnancy:biochemically validated only Show forest plot | 3 | Risk Ratio (M‐H, Random, 95% CI) | Totals not selected | |
| 2.1 Single interventions | 1 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 2.2 Multiple interventions | 0 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 2.3 Tailored interventions | 2 | Risk Ratio (M‐H, Random, 95% CI) | 0.0 [0.0, 0.0] | |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 1 | 130 | Risk Ratio (M‐H, Random, 95% CI) | 1.23 [0.87, 1.74] |
| 3.1 Single interventions | 1 | 130 | Risk Ratio (M‐H, Random, 95% CI) | 1.23 [0.87, 1.74] |
| 4 Abstinence at 18 + months postpartum Show forest plot | 1 | 73 | Risk Ratio (M‐H, Random, 95% CI) | 1.07 [0.58, 1.98] |
| 4.1 Multiple interventions | 1 | 73 | Risk Ratio (M‐H, Random, 95% CI) | 1.07 [0.58, 1.98] |
| 5 Smoking reduction: mean cigarettes per day Show forest plot | 2 | 271 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.31 [‐0.55, ‐0.07] |
| 5.1 Single interventions | 1 | 130 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.22 [‐0.57, 0.12] |
| 5.2 Tailored interventions | 1 | 141 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.40 [‐0.73, ‐0.06] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy Show forest plot | 3 | 455 | Risk Ratio (M‐H, Random, 95% CI) | 1.06 [0.68, 1.63] |
| 1.1 Single interventions | 2 | 262 | Risk Ratio (M‐H, Random, 95% CI) | 0.98 [0.40, 2.39] |
| 1.2 Multiple interventions | 1 | 193 | Risk Ratio (M‐H, Random, 95% CI) | 0.99 [0.51, 1.92] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 2 | 389 | Risk Ratio (M‐H, Random, 95% CI) | 1.13 [0.72, 1.78] |
| 2.1 Single interventions | 1 | 196 | Risk Ratio (M‐H, Random, 95% CI) | 1.28 [0.68, 2.39] |
| 2.2 Multiple interventions | 1 | 193 | Risk Ratio (M‐H, Random, 95% CI) | 0.99 [0.51, 1.92] |
| 3 Abstinence at 0 to 5 months postpartum Show forest plot | 2 | 389 | Risk Ratio (M‐H, Random, 95% CI) | 0.89 [0.51, 1.55] |
| 3.1 Single interventions | 1 | 196 | Risk Ratio (M‐H, Random, 95% CI) | 0.91 [0.41, 2.03] |
| 3.2 Multiple interventions | 1 | 193 | Risk Ratio (M‐H, Random, 95% CI) | 0.88 [0.41, 1.89] |
| 4 Smoking reduction: self reported mean cigarettes per day Show forest plot | 1 | 64 | Std. Mean Difference (IV, Fixed, 95% CI) | 0.15 [‐0.34, 0.64] |
| 4.1 Single interventions | 1 | 64 | Std. Mean Difference (IV, Fixed, 95% CI) | 0.15 [‐0.34, 0.64] |
| Outcome or subgroup title | No. of studies | No. of participants | Statistical method | Effect size |
| 1 Abstinence in late pregnancy: self‐reported and biochemically validated Show forest plot | 97 | 26637 | Risk Ratio (M‐H, Random, 95% CI) | 1.35 [1.23, 1.48] |
| 1.1 Counselling | 51 | 18276 | Risk Ratio (M‐H, Random, 95% CI) | 1.31 [1.16, 1.47] |
| 1.2 Health education | 11 | 2142 | Risk Ratio (M‐H, Random, 95% CI) | 1.22 [0.97, 1.55] |
| 1.3 Feedback | 6 | 859 | Risk Ratio (M‐H, Random, 95% CI) | 1.92 [1.16, 3.17] |
| 1.4 Incentives | 13 | 1752 | Risk Ratio (M‐H, Random, 95% CI) | 1.88 [1.12, 3.14] |
| 1.5 Social support | 14 | 2629 | Risk Ratio (M‐H, Random, 95% CI) | 1.16 [0.96, 1.40] |
| 1.6 Exercise | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.72, 2.01] |
| 1.7 Other | 1 | 194 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.62, 4.32] |
| 2 Abstinence in late pregnancy: biochemically validated only Show forest plot | 73 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 2.1 Counselling | 37 | 14521 | Risk Ratio (M‐H, Random, 95% CI) | 1.23 [1.10, 1.38] |
| 2.2 Health education | 8 | 1744 | Risk Ratio (M‐H, Random, 95% CI) | 1.16 [0.87, 1.55] |
| 2.3 Feedback | 4 | 683 | Risk Ratio (M‐H, Random, 95% CI) | 1.60 [0.85, 3.03] |
| 2.4 Incentives | 13 | 1788 | Risk Ratio (M‐H, Random, 95% CI) | 1.82 [1.10, 3.03] |
| 2.5 Social support | 9 | 1723 | Risk Ratio (M‐H, Random, 95% CI) | 1.08 [0.94, 1.24] |
| 2.6 Exercise | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.72, 2.01] |
| 2.7 Other | 1 | 194 | Risk Ratio (M‐H, Random, 95% CI) | 1.63 [0.62, 4.32] |
| 3 Continued abstinence (Relapse prevention) in late pregnancy for spontaneous quitters Show forest plot | 15 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 3.1 Counselling | 13 | 1538 | Risk Ratio (M‐H, Random, 95% CI) | 1.01 [0.92, 1.09] |
| 3.2 Health education | 1 | 70 | Risk Ratio (M‐H, Random, 95% CI) | 1.02 [0.86, 1.23] |
| 3.3 Social support | 1 | 158 | Risk Ratio (M‐H, Random, 95% CI) | 1.01 [0.86, 1.20] |
| 4 Abstinence at 0 to 5 months postpartum Show forest plot | 35 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 4.1 Counselling | 21 | 5891 | Risk Ratio (M‐H, Random, 95% CI) | 1.29 [1.13, 1.46] |
| 4.2 Health education | 5 | 1378 | Risk Ratio (M‐H, Random, 95% CI) | 1.50 [1.02, 2.20] |
| 4.3 Incentives | 4 | 400 | Risk Ratio (M‐H, Random, 95% CI) | 2.23 [0.94, 5.30] |
| 4.4 Social support | 5 | 697 | Risk Ratio (M‐H, Random, 95% CI) | 1.09 [0.86, 1.37] |
| 5 Abstinence at 6 to 11 months postpartum Show forest plot | 19 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 5.1 Counselling | 11 | 4277 | Risk Ratio (M‐H, Random, 95% CI) | 1.15 [0.98, 1.34] |
| 5.2 Incentives | 4 | 804 | Risk Ratio (M‐H, Random, 95% CI) | 3.39 [1.99, 5.76] |
| 5.3 Social support | 3 | 434 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.75, 1.49] |
| 5.4 Exercise | 1 | 785 | Risk Ratio (M‐H, Random, 95% CI) | 1.50 [0.81, 2.79] |
| 6 Abstinence at 12 to 17 months postpartum Show forest plot | 6 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 6.1 Counselling | 5 | 1910 | Risk Ratio (M‐H, Random, 95% CI) | 1.37 [0.98, 1.91] |
| 6.2 Social support | 1 | 292 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.69, 1.60] |
| 7 Abstinence at 18+ months postpartum Show forest plot | 4 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 7.1 Counselling | 3 | 798 | Risk Ratio (M‐H, Random, 95% CI) | 0.98 [0.50, 1.92] |
| 7.2 Social support | 1 | 73 | Risk Ratio (M‐H, Random, 95% CI) | 1.07 [0.58, 1.98] |
| 8 Smoking reduction: numbers of women reducing smoking in late pregnancy Show forest plot | 18 | Risk Ratio (M‐H, Random, 95% CI) | Subtotals only | |
| 8.1 Biochemically validated reduction | 10 | 2531 | Risk Ratio (M‐H, Random, 95% CI) | 1.26 [0.93, 1.71] |
| 8.2 Self‐reported some reduction in smoking (various definitions) | 4 | 499 | Risk Ratio (M‐H, Random, 95% CI) | 1.61 [1.22, 2.12] |
| 8.3 Self‐reported > 50% reduction in smoking | 4 | 1872 | Risk Ratio (M‐H, Random, 95% CI) | 1.29 [1.08, 1.54] |
| 9 Smoking reduction: biochemical measures in late pregnancy Show forest plot | 10 | Std. Mean Difference (IV, Random, 95% CI) | Subtotals only | |
| 9.1 Mean cotinine levels | 9 | 2258 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.41 [‐0.66, ‐0.15] |
| 9.2 Mean thiocyanate level | 1 | 769 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.29 [‐0.44, ‐0.15] |
| 10 Smoking reduction: self‐reported mean cigarettes per day measured in late pregnancy or at delivery Show forest plot | 24 | Std. Mean Difference (IV, Random, 95% CI) | Subtotals only | |
| 10.1 Counselling | 13 | 3814 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.19 [‐0.36, ‐0.01] |
| 10.2 Health education | 4 | 1436 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.29 [‐0.71, 0.14] |
| 10.3 Feedback | 2 | 3675 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.18 [‐1.02, 0.67] |
| 10.4 Incentives | 1 | 74 | Std. Mean Difference (IV, Random, 95% CI) | ‐1.43 [‐1.94, ‐0.91] |
| 10.5 Social support | 4 | 736 | Std. Mean Difference (IV, Random, 95% CI) | ‐0.23 [‐0.39, ‐0.07] |
| 11 Low birthweight (under 2500 g) Show forest plot | 18 | 9402 | Risk Ratio (M‐H, Random, 95% CI) | 0.83 [0.72, 0.94] |
| 11.1 Counselling | 8 | 4339 | Risk Ratio (M‐H, Random, 95% CI) | 0.83 [0.68, 1.01] |
| 11.2 Health education | 2 | 1172 | Risk Ratio (M‐H, Random, 95% CI) | 0.87 [0.49, 1.55] |
| 11.3 Feedback | 1 | 2848 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.63, 1.06] |
| 11.4 Incentives | 5 | 252 | Risk Ratio (M‐H, Random, 95% CI) | 0.63 [0.37, 1.08] |
| 11.5 Social support | 1 | 79 | Risk Ratio (M‐H, Random, 95% CI) | 1.00 [0.33, 2.99] |
| 11.6 Exercise | 1 | 712 | Risk Ratio (M‐H, Random, 95% CI) | 0.88 [0.58, 1.32] |
| 12 Very low birthweight (under 1500 g) Show forest plot | 3 | 4366 | Risk Ratio (M‐H, Random, 95% CI) | 1.11 [0.62, 2.01] |
| 12.1 Counselling | 2 | 1666 | Risk Ratio (M‐H, Random, 95% CI) | 1.27 [0.60, 2.71] |
| 12.2 Feedback | 1 | 2700 | Risk Ratio (M‐H, Random, 95% CI) | 0.90 [0.35, 2.32] |
| 13 Preterm birth (under 37 weeks) Show forest plot | 19 | 9222 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.77, 1.11] |
| 13.1 Counselling | 8 | 3447 | Risk Ratio (M‐H, Random, 95% CI) | 0.93 [0.71, 1.20] |
| 13.2 Health education | 2 | 1170 | Risk Ratio (M‐H, Random, 95% CI) | 0.92 [0.55, 1.56] |
| 13.3 Feedback | 2 | 3111 | Risk Ratio (M‐H, Random, 95% CI) | 0.60 [0.28, 1.29] |
| 13.4 Incentives | 6 | 790 | Risk Ratio (M‐H, Random, 95% CI) | 0.91 [0.52, 1.59] |
| 13.5 Exercise | 1 | 704 | Risk Ratio (M‐H, Random, 95% CI) | 1.32 [0.81, 2.14] |
| 14 Mean birthweight (g) Show forest plot | 26 | 11338 | Mean Difference (IV, Random, 95% CI) | 55.60 [29.82, 81.38] |
| 14.1 Counselling | 14 | 5471 | Mean Difference (IV, Random, 95% CI) | 42.17 [11.79, 72.55] |
| 14.2 Health education | 2 | 1172 | Mean Difference (IV, Random, 95% CI) | 27.35 [‐53.88, 108.58] |
| 14.3 Feedback | 2 | 3006 | Mean Difference (IV, Random, 95% CI) | 79.43 [‐53.05, 211.91] |
| 14.4 Incentives | 6 | 834 | Mean Difference (IV, Random, 95% CI) | 114.01 [63.91, 164.11] |
| 14.5 Social support | 1 | 142 | Mean Difference (IV, Random, 95% CI) | 28.0 [‐152.48, 208.48] |
| 14.6 Exercise | 1 | 713 | Mean Difference (IV, Random, 95% CI) | ‐14.40 [‐104.15, 75.35] |
| 15 Stillbirths Show forest plot | 8 | 6170 | Risk Ratio (M‐H, Random, 95% CI) | 1.20 [0.76, 1.90] |
| 15.1 Counselling | 5 | 2454 | Risk Ratio (M‐H, Random, 95% CI) | 1.14 [0.55, 2.33] |
| 15.2 Feedback | 2 | 2960 | Risk Ratio (M‐H, Random, 95% CI) | 1.28 [0.69, 2.39] |
| 15.3 Exercise | 1 | 756 | Risk Ratio (M‐H, Random, 95% CI) | 1.01 [0.14, 7.10] |
| 16 Perinatal deaths Show forest plot | 4 | 4465 | Risk Ratio (M‐H, Random, 95% CI) | 1.13 [0.72, 1.77] |
| 16.1 Counselling | 2 | 1065 | Risk Ratio (M‐H, Random, 95% CI) | 1.10 [0.52, 2.31] |
| 16.2 Health education | 1 | 552 | Risk Ratio (M‐H, Random, 95% CI) | 4.40 [0.49, 39.08] |
| 16.3 Feedback | 1 | 2848 | Risk Ratio (M‐H, Random, 95% CI) | 1.05 [0.59, 1.87] |
| 17 Neonatal deaths Show forest plot | 5 | 5680 | Risk Ratio (M‐H, Random, 95% CI) | 1.04 [0.41, 2.64] |
| 17.1 Counselling | 3 | 2095 | Risk Ratio (M‐H, Random, 95% CI) | 2.06 [0.61, 6.92] |
| 17.2 Feedback | 1 | 2810 | Risk Ratio (M‐H, Random, 95% CI) | 0.40 [0.08, 2.07] |
| 17.3 Exercise | 1 | 775 | Risk Ratio (M‐H, Random, 95% CI) | 0.34 [0.01, 8.31] |
| 18 NICU admissions Show forest plot | 8 | 2100 | Risk Ratio (M‐H, Random, 95% CI) | 0.78 [0.61, 0.98] |
| 18.1 Counselling | 2 | 1140 | Risk Ratio (M‐H, Random, 95% CI) | 0.82 [0.52, 1.29] |
| 18.2 Incentives | 5 | 252 | Risk Ratio (M‐H, Random, 95% CI) | 0.77 [0.51, 1.15] |
| 18.3 Exercise | 1 | 708 | Risk Ratio (M‐H, Random, 95% CI) | 0.76 [0.47, 1.22] |
