Interventions for promoting smoking cessation during pregnancy
Abstract
Background
Tobacco smoking in pregnancy remains one of the few preventable factors associated with complications in pregnancy, low birthweight, preterm birth and has serious long‐term health implications for women and babies. Smoking in pregnancy is decreasing in high‐income countries and increasing in low‐ to middle‐income countries and is strongly associated with poverty, low educational attainment, poor social support and psychological illness.
Objectives
To assess the effects of smoking cessation interventions during pregnancy on smoking behaviour and perinatal health outcomes.
Search methods
We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (June 2008), the Cochrane Tobacco Addiction Group's Trials Register (June 2008), EMBASE, PsycLIT, and CINAHL (all from January 2003 to June 2008). We contacted trial authors to locate additional unpublished data.
Selection criteria
Randomised controlled trials where smoking cessation during pregnancy was a primary aim of the intervention.
Data collection and analysis
Trials were identified and data extracted by one person and checked by a second. Subgroup analysis was conducted to assess the effect of risk of trial bias, intensity of the intervention and main intervention strategy used.
Main results
Seventy‐two trials are included. Fifty‐six randomised controlled trials (over 20,000 pregnant women) and nine cluster‐randomised trials (over 5000 pregnant women) provided data on smoking cessation outcomes.
There was a significant reduction in smoking in late pregnancy following interventions (risk ratio (RR) 0.94, 95% confidence interval (CI) 0.93 to 0.96), an absolute difference of six in 100 women who stopped smoking during pregnancy. However, there is significant heterogeneity in the combined data (I2 > 60%). In the trials with the lowest risk of bias, the interventions had less effect (RR 0.97, 95% CI 0.94 to 0.99), and lower heterogeneity (I2 = 36%). Eight trials of smoking relapse prevention (over 1000 women) showed no statistically significant reduction in relapse.
Smoking cessation interventions reduced low birthweight (RR 0.83, 95% CI 0.73 to 0.95) and preterm birth (RR 0.86, 95% CI 0.74 to 0.98), and there was a 53.91g (95% CI 10.44 g to 95.38 g) increase in mean birthweight. There were no statistically significant differences in neonatal intensive care unit admissions, very low birthweight, stillbirths, perinatal or neonatal mortality but these analyses had very limited power.
Authors' conclusions
Smoking cessation interventions in pregnancy reduce the proportion of women who continue to smoke in late pregnancy, and reduce low birthweight and preterm birth. Smoking cessation interventions in pregnancy need to be implemented in all maternity care settings. Given the difficulty many pregnant women addicted to tobacco have quitting during pregnancy, population‐based measures to reduce smoking and social inequalities should be supported.
PICOs
Plain language summary
Interventions to help women to stop smoking in pregnancy
Smoking during pregnancy increases the risk of the mother having complications during pregnancy and the baby being born too small (with low birthweight) and too early (prematurely, before 37 weeks). Low birthweight has been associated with coronary heart disease, type 2 diabetes, and being overweight in adulthood. Tobacco smoking also has serious long‐term health risks for both the women and their babies. Tobacco smoking during pregnancy is relatively common, although the trend is toward becoming less frequent in high‐income countries and more so in low to middle‐income countries. Many mothers find it hard to stop or reduce smoking during pregnancy even knowing the benefits of doing so as the nicotine in tobacco is very addictive. Smoking in pregnancy is also strongly associated with poverty, low levels of education, poor social support, depression and psychological illness.
The interventions offered to promote smoking cessation in pregnancy are generally given individually and include cognitive behaviour and motivational interviewing; offering incentives; interventions based on stages of change; giving feedback to the mothers on fetal health status or nicotine by‐products measurements; nicotine replacement therapy, bupropion or other medications. The review of trials found a total of 72 controlled trials involving over 25,000 women. These were conducted from 1975 to 2008 and nearly all were in high‐income countries. Interventions were effective in helping women to stop smoking during pregnancy (overall by approximately 6%). The most effective intervention appeared to be providing incentives, which helped around 24% of women to quit smoking during pregnancy. The smoking cessation interventions reduced the number of babies with low birthweight and preterm births, confirming that smoking cessation can reduce the adverse effects of smoking on newborn infants.
Women in the control groups of most trials received information about the risks of smoking in pregnancy and were advised to quit as part of usual care. The intensity of both that information and the interventions has increased over time.
