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Cochrane Database of Systematic Reviews Protocol - Intervention

Relaxation therapy for preventing and treating preterm labour

Authors' declarations of interest

Version published: 08 October 2008 Version history

https://doi.org/10.1002/14651858.CD007426

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Abstract

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:

To evaluate the effectiveness of relaxation therapies for preventing and/or treating preterm labour and/or preterm birth.

Background

Preterm birth

Preterm birth is a leading cause of perinatal mortality and morbidity (von der Pool 1998; Weismiller 1999). The major burden of preterm birth is in the developing world; however, even in developed countries, rates of preterm birth have remained unchanged or are on the increase (Steer 2006). Preterm birth, defined as birth before 37 completed weeks' gestation, is a complication that affects between 5% and 10% of all births in developed countries (Burke 2000; von der Pool 1998; Weismiller 1999) and has a profound effect on a baby's survival and health. In spite of significant improvements in neonatal care, preterm birth is still the leading cause of neonatal deaths and one of the commonest obstetric complications. Adverse outcomes associated with preterm birth include respiratory distress syndrome, infections, congenital heart defects and thermoregulation problems (Witter 1993). Babies born prematurely are ill‐equipped for extrauterine life and require special care for their ongoing development.

Preterm birth also imposes substantial physical, emotional and financial burdens on families, and stretches the resources of health services. It is estimated, for example, that caring for preterm babies accounts for around five million hospital days a year worldwide and costs over $5 billion (Witter 1993). Lifetime costs have been estimated at $950,000 per baby (Kiss 2004).

About two‐thirds of preterm births in developed countries result from spontaneous preterm labour due to a variety of causes (Steer 2006). Although the pathogenesis of preterm labour is not well understood, several factors are thought to contribute to its occurrence: demographic and psychosocial; obstetric; nutritional; maternal morbidity during pregnancy; and toxic exposure (Witter 1993). Several studies have found maternal psychological stress to be a predictor of adverse pregnancy outcomes, such as low birthweight, prematurity and intrauterine growth retardation (Chung 2001; Rondo 2003). The release of catecholamines associated with maternal stress can restrict the flow of oxygen and nutrients to the fetus and may precipitate premature labour (Omer 1986).

Relaxation

Relaxation or mind‐body therapies are often used to treat stress‐ and anxiety‐related psychological and physical disorders. They include techniques whose stated goal is attainment of a psycho‐physiological state of relaxation or hypoarousal (Astin 2003). The relaxation response provides a counterbalance to the harmful effects of stress by lowering, among other things, the heart rate, blood pressure, respiratory rate and by reducing muscular tension. Yet, although stress is thought to play a significant role in the onset of preterm labour, relaxation has received little attention as a potentially cost‐effective intervention.

Relaxation therapies cover a broad range of techniques and practices, including meditation, biofeedback, hypnosis, massage, reflexology, breathing exercises, visualisation, aromatherapy, yoga, water therapy and music therapy. Several of these are described here in more detail. Meditation is the process whereby the individual tries to focus attention on one thought or object to the exclusion of all others (Davis 1998). Biofeedback uses instruments to detect changes in the body's physical state that are relayed to the individual in the form of visual or auditory feedback (Davis 1998). In hypnosis, peripheral awareness is suspended, leading to a heightened sense of concentration that can be channeled to counteract stress (Astin 2003). Visualisation is concerned with positive thinking to overcome physical symptoms, and can be particularly effective in treating stress‐related illnesses (Davis 1998). Aromatherapy involves the use of liquid plant materials, known as essential oils, for the purpose of affecting a person's mood or health (Davis 1998).

Several published studies have investigated the effect of relaxation techniques on preventing preterm labour and birth, but we are not aware of any systematic reviews. A recent randomised controlled trial in which women with uncomplicated singleton pregnancies followed a nurse‐led seven‐week applied relaxation training intervention resulted in lower rates of low birthweight and caesarean section, but had no effect in the rate of preterm birth (Bastani 2006). In another study that used historical controls, hypnotic relaxation was used as an adjunct to pharmacologic treatment in women hospitalised for premature contractions in pregnancy (Omer 1986). Preterm birth remains a major problem in perinatal medicine. If proven to be effective, relaxation techniques potentially offer a safe and simple means of improving outcomes for mothers and babies.

Objectives

To evaluate the effectiveness of relaxation therapies for preventing and/or treating preterm labour and/or preterm birth.

Methods

Criteria for considering studies for this review

Types of studies

Randomised and quasi‐randomised trials comparing relaxation techniques with usual care, no treatment or sham interventions to prevent or treat preterm labour. We will also include cluster‐randomised trials.

Types of participants

All pregnant women including women with a history of preterm birth and/or women deemed at risk of preterm birth and/or women with preterm labour .

Types of interventions

Relaxation therapy versus usual care, no treatment or sham interventions to prevent or treat preterm labour. Relaxation techniques may include meditation, biofeedback, massage, reflexology, deep breathing, hypnosis, visualisation, aromatherapy, yoga, water therapy and music therapy.

Types of outcome measures

Primary outcomes
For women in preterm labour

  1. Prolongation of pregnancy: duration of pregnancy after starting treatment;

  2. birthweight;

  3. neonatal death;

  4. respiratory distress syndrome (RDS);

  5. intraventricular hemorrhage (IVH);

  6. necrotising enterocolitis (NEC);

  7. length of stay;

  8. admission to neonatal intensive care unit (NICU);

  9. preterm labour.

For women not in preterm labour

  1. Length of gestation: gestational age at delivery;

  2. preterm labour;

  3. birthweight;

  4. neonatal death;

  5. RDS;

  6. IVH;

  7. NEC;

  8. length of stay;

  9. admission to NICU.

Secondary outcomes

  1. Stillbirth;

  2. type of delivery;

  3. Apgar score less than seven at five minutes;

  4. maternal anxiety and stress;

  5. women's experiences and views: satisfaction.

Search methods for identification of studies

Electronic searches

We will contact the Trials Search Co‐ordinator to search the Cochrane Pregnancy and Childbirth Group’s Trials Register. 

The Cochrane Pregnancy and Childbirth Group’s Trials Register is maintained by the Trials Search Co‐ordinator and contains trials identified from:

  1. quarterly searches of the Cochrane Central Register of Controlled Trials (CENTRAL);

  2. weekly searches of MEDLINE;

  3. handsearches of 30 journals and the proceedings of major conferences;

  4. weekly current awareness alerts for a further 44 journals plus monthly BioMed Central email alerts.

Details of the search strategies for CENTRAL and MEDLINE, the list of handsearched journals and conference proceedings, and the list of journals reviewed via the current awareness service can be found in the ‘Specialized Register’ section within the editorial information about the Cochrane Pregnancy and Childbirth Group.

Trials identified through the searching activities described above are each assigned to a review topic (or topics). The Trials Search Co‐ordinator searches the register for each review using the topic list rather than keywords.

In addition, we will search CENTRAL (The Cochrane Library), CINAHL (1982 to current) and EMBASE (January 1985 to current) using the search strategy detailed in Appendix 1.

We will not apply any language restrictions.

Data collection and analysis

Selection of studies

We will assess for inclusion all potential studies we identify as a result of the search strategy. We will resolve any disagreement through discussion or if required consult an outside person.

Data extraction and management

We will modify the Cochrane Pregnancy and Childbirth data extraction form to extract data. At least two review authors will extract the data using the agreed form. We will resolve discrepancies through discussion. We will use the Review Manager software (RevMan 2008) to double enter all the data or a subsample. When information regarding any of the above is unclear, we will attempt to contact authors of the original reports to provide further details.

Assessment of methodological quality of included studies

We will assess the validity of each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2008). Methods used for generation of the randomisation sequence will be described for each trial.

(1) Selection bias (randomisation and allocation concealment)

We will assign a quality score for each trial, using the following criteria:
(A) adequate concealment of allocation: such as telephone randomisation, consecutively numbered, sealed opaque envelopes;
(B) unclear whether adequate concealment of allocation: such as list or table used, sealed envelopes, or study does not report any concealment approach;
(C) inadequate concealment of allocation: such as open list of random‐number tables, use of case record numbers, dates of birth or days of the week.

We will include quasi‐randomised trials in this review as it is expected that such studies could make a useful contribution even if they are not truly randomised. We will perform a sensitivity analysis by trial quality.

(2) Attrition bias (loss of participants, for example, withdrawals, dropouts, protocol deviations)

We will assess completeness to follow up using the following criteria:

(A) less than 5% loss of participants;

(B) 5% to 9.9% loss of participants;

(C) 10% to 19.9% loss of participants;

(D) more than 20% loss of participants.

(3) Performance bias (blinding of participants, researchers and outcome assessment)

We will assess blinding using the following criteria:

(1) blinding of participants (yes/no/unclear);

(2) blinding of caregiver (yes/no/unclear);

(3) blinding of outcome assessment (yes/no/unclear).

Measures of treatment effect

We will carry out statistical analysis using the Review Manager software (RevMan 2008). We will use fixed‐effect meta‐analysis for combining data in the absence of significant heterogeneity if trials are sufficiently similar. If heterogeneity is found, we will explore this by sensitivity analysis followed by random‐effects if required.

Dichotomous data

For dichotomous data, we will present results as summary relative risk with 95% confidence intervals.

Continuous data

For continuous data, we will use the mean difference if outcomes are measured in the same way between trials. We will use the standardised mean difference to combine trials that measure the same outcome, but use different methods. If there is evidence of skewness, we will report this.

Unit of analysis issues

Cluster‐randomised trials

We will include cluster‐randomised trials in the analyses along with individually randomised trials. Their sample sizes will be adjusted using the methods described in Gates 2005, using an estimate of the intracluster correlation co‐efficient (ICC) derived from the trial (if possible), or from another source. If ICCs from other sources are used, we will report this and conduct sensitivity analyses to investigate the effect of variation in the ICC. If we identify both cluster‐randomised trials and individually randomised trials, we plan to synthesise the relevant information. We will consider it reasonable to combine the results from both if there is little heterogeneity between the study designs, and if the interaction between the effect of intervention and the choice of randomisation unit is considered to be unlikely.

We will also acknowledge heterogeneity in the randomisation unit and perform a separate meta‐analysis. Therefore the meta‐analysis will be performed in two parts as well.

Cross‐over trials

We will not include cross‐over trials for analysis.

Dealing with missing data

We will analyse data on all participants with available data in the group to which they are allocated, regardless of whether or not they received the allocated intervention. If in the original reports participants are not analysed in the group to which they were randomised, and there is sufficient information in the trial report, we will attempt to restore them to the correct group.

Assessment of heterogeneity

We will apply tests of heterogeneity between trials, if appropriate, using the I2 statistic. If we identify high levels of heterogeneity among the trials (exceeding 50%), we will explore it by prespecified subgroup analysis and perform sensitivity analysis. We will use a random‐effects meta‐analysis as an overall summary if this is considered appropriate.

Subgroup analyses

We will conduct planned subgroup analyses classifying whole trials by interaction tests as described by Deeks 2001. We plan to subgroup according to preterm labour risk for studies that include women not in preterm labour. If there are sufficient studies, we will also subgroup according to the type of relaxation technique (e.g. hypnosis, yoga etc.). In relation to preterm labour risk, we plan to carry out the following subgroup analyses:

‐ women deemed at high risk of preterm labour compared with women not deemed at high risk of preterm labour.

Sensitivity analyses

We will carry out sensitivity analysis to explore the effect of trial quality. This will involve analysis based on an A, B, C or D rating of selection bias and attrition bias. Studies of poor quality will be excluded in the analysis (those rating B, C or D) in order to assess for any substantive difference to the overall result.

As we will include cluster‐randomised trials, we will apply other sensitivity analysis incorporating an estimate of the ICC borrowed from a different trial, to see what the effect of different values of the ICC on the results of the analysis would be.