A randomized trial to promote health belief and to reduce environmental tobacco smoke exposure in pregnant women

[Passive Smoking and Pregnancy - CNGOF-SFT Expert Report and Guidelines for Smoking Management during Pregnancy]

OBJECTIVE

The objective of this chapter is to evaluate the risks of second-hand-smoke during pregnancy and to assess the benefits of antenatal care.

METHODS

Bibliographical research in French and English using the Medline and Cochrane databases and the recommendations of international societies.

RESULTS

Exposure to second-hand smoke appears to be higher at home and in the car, with potential consequences for pregnancy, especially prematurity (NP3). Complete avoidance of smoking at home significantly reduces exposure to passive smoking compared to incomplete avoidance (NP4). The more numerous the sources, the higher the intoxication is (NP4). The major risk factor associated with passive smoking is the presence of a spouse who smokes. Other associated factors are the presence of a smoker at home or in the car, young population (<25 years), low level of education, old smoking (NP4). Passive smoking is associated with an increased risk of fetal death in utero, fetal malformations, prematurity and birth weight under 2500g (NP2). No specific management is recommended for all pregnant women. Nevertheless, in a specific population of pregnant women with vulnerabilities, a behavioral approach aimed at teaching them to negotiate with their entourage may be beneficial in order to reduce the effects of passive smoking on pregnancy (NP2).

CONCLUSION

It is recommended to advise women and their family (especially spouses) to create a smoke-free environment, especially at home and in the car (professional consensus). It is recommended to provide a minimum amount of smoking cessation advice to pregnant women's entourage (professional consensus).

Reducing Secondhand Smoke Exposure Among Nonsmoking Pregnant Women: A Systematic Review

Introduction

Exposure to secondhand smoke (SHS) in pregnancy leads to an increased risk of stillbirths, congenital malformations, and low birth weight. There is a lack of evidence about how best to achieve reductions in SHS exposure among nonsmoking pregnant women. This work systematically reviews individual or household interventions to reduce pregnant women’s exposure to SHS.

Methods

MEDLINE, EMBASE, and CINAHL databases were searched from their dates of inception to April 17, 2019. Studies were included if: participants were nonsmoking pregnant women; involved an intervention to reduce SHS exposure or encourage partner quitting; and measured SHS exposure of pregnant women and/or recorded quit rates among partners. The UK National Institute for Health & Care Excellence (NICE) Quality Appraisal checklist was used to determine internal and external validity.

Results

Nine studies met the inclusion criteria. Educational interventions were primarily targeted at the pregnant woman to change her or others’ behavior, with only two studies involving the partner who smoked. Intervention delivery was mixed, spanning brief discussions through to more involving sessions with role play. The effective interventions involved multiple follow-ups. There was no standardized method of assessing exposure to SHS. Many of the included studies had moderate to high risk of bias.

Conclusion

There is mixed evidence for interventions aimed at reducing pregnant women’s exposure to SHS, though multi-component interventions seem to be more effective. The effectiveness of family-centered approaches involving creating smoke-free homes alongside partner smoking cessation, perhaps involving pharmacological support and/or financial incentives, should be explored.

Implications

• Measures to protect nonsmoking pregnant women from SHS tend to place the responsibility for “avoidance” on the woman.

• There is little work that seeks to involve the smoking partner or other smokers in protecting pregnant women from SHS.

• Interventions to create smoke-free homes and/or smoking partner cessation need to be developed: pharmacological and financial support should be explored.

Exposure to secondhand smoke in Iranian pregnant women at home and the related factors

INTRODUCTION

Fetus health is of high importance in pregnant women and exposure to secondhand smoke (SHS) endangers maternal and fetal health. Therefore, in this study we examined the prevalence of exposure to SHS in pregnant women at home and the related factors.

METHODS

This cross-sectional study was conducted with 255 pregnant women who were referred to the Isfahan health care center from July to September 2018. A questionnaire that was designed by the research team was applied to collect data about the participants' prevalence of exposure, attitude-emotional dimension, perceived susceptibility, perceived severity, and perceived barriers. The questionnaire used was self-administered. The validity and reliability of the questionnaire were confirmed by a panel of experts. Cronbach's alpha of attitude-emotional dimension, perceived susceptibility, perceived severity, and perceived barriers were also calculated as 0.81, 0.91, 0.92, and 0.89, respectively. Statistically significant differences were examined using chi-squared test and Mann-Whitney test.

RESULTS

We found that the prevalence of exposure to SHS in pregnant women was 23.1%. The age of the husband (p=0.041), education level of the smoking husband (p=0.005), the education level of the pregnant woman (p=0.002), employment status of husband (p=0.010), and whether the pregnancy was planned (p=0.010) had significant association with the participant prevalence of exposure to SHS. Thus, older age of husbands, lower education levels of husbands and wives, unwanted pregnancies, and unemployment of husbands resulted in higher exposure to SHS. The mean scores of knowledge and perceptions were lower in women exposed to smoke than in non-exposed women (p<0.05).

CONCLUSIONS

The rate of SHS exposure was high in pregnant women. The knowledge and perception scores of exposed women to SHS were lower than those of non-exposed women. Low levels of education of husbands and women, unemployment and higher age of husbands, and unwanted pregnancies were considered as health risk factors. Therefore, effective training programs should be designed to educate pregnant women and their husbands.

An educational intervention to men for reducing environmental tobacco smoke exposure in their pregnant wives

OBJECTIVE

To determine the effect of education based on health belief model (HBM) on the level of their pregnant wives' environmental tobacco smoke exposure (ETSE).

METHODS

This interventional randomized study was conducted on 60 cigarette smoking men who have exposed their pregnant wives to smoke during of their pregnancy. The HBM constructs and weekly ETSE were evaluated by using questionnaire. The intervention group received education with emphasis on the risks of cigarette's smoke on the pregnancy. Then right after the training and 6 weeks after that, HBM constructs and 6 weeks after the training the weekly ETSE were evaluated again.

RESULTS

Results showed a significant difference between the mean of perceived susceptibility, perceived benefits and barriers at intake and 6 weeks after the intervention in the intervention group. Also, the level of perceived susceptibility/severity and perceived barriers in both groups were significantly different 6 weeks after the intervention compared to intake time. The ETSE was significantly lower in the intervention group 6 weeks after the intervention in comparison to before the intervention and also to the control group.

CONCLUSIONS

This study showed that education husbands would relatively improve their health beliefs and reduce the ETSE of their pregnant wives.

Behaviour change interventions to reduce second-hand smoke exposure at home in pregnant women - a systematic review and intervention appraisal

BACKGROUND

Second-hand smoke (SHS) exposure during pregnancy is associated with poor pregnancy and foetal outcomes. Theory-based behaviour change interventions (BCI) have been used successfully to change smoking related behaviours and offer the potential to reduce exposure of SHS in pregnant women. Systematic reviews conducted so far do not evaluate the generalisability and scalability of interventions. The objectives of this review were to (1) report the BCIs for reduction in home exposure to SHS for pregnant women; and (2) critically appraise intervention-reporting, generalisability, feasibility and scalability of the BCIs employed.

METHODS

Standard methods following PRISMA guidelines were employed. Eight databases were searched from 2000 to 2015 in English. The studies included used BCIs on pregnant women to reduce their home SHS exposure by targeting husbands/partners. The Workgroup for Intervention Development and Evaluation Research (WIDER) guidelines were used to assess intervention reporting. Generalisability, feasibility and scalability were assessed against criteria described by Bonell and Milat.

RESULTS

Of 3479 papers identified, six studies met the inclusion criteria. These studies found that BCIs led to increased knowledge about SHS harms, reduction or husbands quitting smoking, and increased susceptibility and change in level of actions to reduce SHS at home. Two studies reported objective exposure measures, and one reported objective health outcomes. The studies partially followed WIDER guidelines for reporting, and none met all generalisability, feasibility and scalability criteria.

CONCLUSIONS

There is a dearth of literature in this area and the quality of studies reviewed was moderate to low. The BCIs appear effective in reducing SHS, however, weak study methodology (self-reported exposure, lack of objective outcome assessment, short follow-up, absence of control group) preclude firm conclusion. Some components of the WIDER checklist were followed for BCI reporting, scalability and feasibility of the studies were not described. More rigorous studies using biochemical and clinical measures for exposures and health outcomes in varied study settings are required. Studies should report interventions in detail using WIDER checklist and assess them for generalisability, feasibility and scalability.

TRIAL REGISTRATION

CRD40125026666.

Psychosocial interventions for supporting women to stop smoking in pregnancy

BACKGROUND

Tobacco smoking remains one of the few preventable factors associated with complications in pregnancy, and has serious long-term implications for women and babies. Smoking in pregnancy is decreasing in high-income countries, but is strongly associated with poverty and is increasing in low- to middle-income countries.

OBJECTIVES

To assess the effects of smoking cessation interventions during pregnancy on smoking behaviour and perinatal health outcomes.

SEARCH METHODS

In this sixth update, we searched the Cochrane Pregnancy and Childbirth Group's Trials Register (13 November 2015), checked reference lists of retrieved studies and contacted trial authors.

SELECTION CRITERIA

Randomised controlled trials, cluster-randomised trials, and quasi-randomised controlled trials of psychosocial smoking cessation interventions during pregnancy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and trial quality, and extracted data. Direct comparisons were conducted in RevMan, with meta-regression conducted in STATA 14.

MAIN RESULTS

The overall quality of evidence was moderate to high, with reductions in confidence due to imprecision and heterogeneity for some outcomes. One hundred and two trials with 120 intervention arms (studies) were included, with 88 trials (involving over 28,000 women) providing data on smoking abstinence in late pregnancy. Interventions were categorised as counselling, health education, feedback, incentives, social support, exercise and dissemination.In separate comparisons, there is high-quality evidence that counselling increased smoking cessation in late pregnancy compared with usual care (30 studies; average risk ratio (RR) 1.44, 95% confidence interval (CI) 1.19 to 1.73) and less intensive interventions (18 studies; average RR 1.25, 95% CI 1.07 to 1.47). There was uncertainty whether counselling increased the chance of smoking cessation when provided as one component of a broader maternal health intervention or comparing one type of counselling with another. In studies comparing counselling and usual care (largest comparison), it was unclear whether interventions prevented smoking relapse among women who had stopped smoking spontaneously in early pregnancy. However, a clear effect was seen in smoking abstinence at zero to five months postpartum (11 studies; average RR 1.59, 95% CI 1.26 to 2.01) and 12 to 17 months (two studies, average RR 2.20, 95% CI 1.23 to 3.96), with a borderline effect at six to 11 months (six studies; average RR 1.33, 95% CI 1.00 to 1.77). In other comparisons, the effect was unclear for most secondary outcomes, but sample sizes were small.Evidence suggests a borderline effect of health education compared with usual care (five studies; average RR 1.59, 95% CI 0.99 to 2.55), but the quality was downgraded to moderate as the effect was unclear when compared with less intensive interventions (four studies; average RR 1.20, 95% CI 0.85 to 1.70), alternative interventions (one study; RR 1.88, 95% CI 0.19 to 18.60), or when smoking cessation health education was provided as one component of a broader maternal health intervention.There was evidence feedback increased smoking cessation when compared with usual care and provided in conjunction with other strategies, such as counselling (average RR 4.39, 95% CI 1.89 to 10.21), but the confidence in the quality of evidence was downgraded to moderate as this was based on only two studies and the effect was uncertain when feedback was compared to less intensive interventions (three studies; average RR 1.29, 95% CI 0.75 to 2.20).High-quality evidence suggests incentive-based interventions are effective when compared with an alternative (non-contingent incentive) intervention (four studies; RR 2.36, 95% CI 1.36 to 4.09). However pooled effects were not calculable for comparisons with usual care or less intensive interventions (substantial heterogeneity, I2 = 93%).High-quality evidence suggests the effect is unclear in social support interventions provided by peers (six studies; average RR 1.42, 95% CI 0.98 to 2.07), in a single trial of support provided by partners, or when social support for smoking cessation was provided as part of a broader intervention to improve maternal health.The effect was unclear in single interventions of exercise compared to usual care (RR 1.20, 95% CI 0.72 to 2.01) and dissemination of counselling (RR 1.63, 95% CI 0.62 to 4.32).Importantly, high-quality evidence from pooled results demonstrated that women who received psychosocial interventions had a 17% reduction in infants born with low birthweight, a significantly higher mean birthweight (mean difference (MD) 55.60 g, 95% CI 29.82 to 81.38 g higher) and a 22% reduction in neonatal intensive care admissions. However the difference in preterm births and stillbirths was unclear. There did not appear to be adverse psychological effects from the interventions.The intensity of support women received in both the intervention and comparison groups has increased over time, with higher-intensity interventions more likely to have higher-intensity comparisons, potentially explaining why no clear differences were seen with increasing intervention intensity in meta-regression analyses. Among meta-regression analyses: studies classified as having 'unclear' implementation and unequal baseline characteristics were less effective than other studies. There was no clear difference between trials implemented by researchers (efficacy studies), and those implemented by routine pregnancy staff (effectiveness studies), however there was uncertainty in the effectiveness of counselling in four dissemination trials where the focus on the intervention was at an organisational level. The pooled effects were similar in interventions provided for women classified as having predominantly low socio-economic status, compared to other women. The effect was significant in interventions among women from ethnic minority groups; however not among indigenous women. There were similar effect sizes in trials with biochemically validated smoking abstinence and those with self-reported abstinence. It was unclear whether incorporating use of self-help manuals or telephone support increased the effectiveness of interventions.

AUTHORS' CONCLUSIONS

Psychosocial interventions to support women to stop smoking in pregnancy can increase the proportion of women who stop smoking in late pregnancy and the proportion of infants born low birthweight. Counselling, feedback and incentives appear to be effective, however the characteristics and context of the interventions should be carefully considered. The effect of health education and social support is less clear. New trials have been published during the preparation of this review and will be included in the next update.

Randomized comparison of group versus individual educational interventions for pregnant women to reduce their secondhand smoke exposure

BACKGROUND

Secondhand smoke (SHS) exposure is deleterious to pregnant women and their unborn children. The prevalence of SHS exposure among pregnant women is particularly high in many Asian countries where approximately half of the male population smokes. We aim to investigate the efficacy of an intervention based on an expanded Health Belief Model (HBM) incorporating self-efficacy to educate and empower pregnant women to reduce their SHS exposure.

METHODS

We conducted a 3-arm randomized controlled trial (N = 50 in each arm) comparing the effectiveness of group-based and individual-based interventions with a treatment-as-usual group. A questionnaire tapping into constructs of the expanded HBM was administered at baseline and 1- and 2-month follow-ups. Exhaled carbon monoxide was used to determine SHS exposure (>=6 ppm). ANOVA was used to compare HBM construct scores, self-efficacy for rejecting SHS exposure, and SHS rejection behavior among the 3 groups at baseline and the 1- and 2-month follow-ups, while logistic regression analysis was used to compare the risk of exposure to SHS at each follow-up.

RESULTS

The group-based intervention significantly improved health beliefs, self-efficacy, and self-reported rejection behaviors. The individual-based intervention effect was limited to some health belief constructs and SHS rejection behaviors. Both group- and individual-based interventions showed significant reductions in SHS exposure 2 months after the intervention (P < 0.0001).

CONCLUSION

Group-based educational interventions based on the HBM are particularly effective in training pregnant women to avoid and refuse exposure to SHS. Policy makers should consider offering group-delivered programs to educate and empower pregnant women to reduce their SHS exposure.

A Clustered Randomized Controlled Trial to Reduce Secondhand Smoke Exposure Among Nonsmoking Pregnant Women in Sichuan Province, China

INTRODUCTION

Nonsmoking pregnant women in China have significant exposure to secondhand smoke (SHS). Few interventions have focused on pregnant women reducing their SHS exposure.

METHODS

This clustered randomized controlled trial, conducted at eight hospitals in Sichuan, China, compared a prenatal health education intervention with usual clinical care as a control. The primary outcome was self-reported "no SHS exposure" before and 3 months after birth. The intervention consisted of three large group educational sessions, standardized clinician advice, brief monthly follow-up calls, and educational materials and resources. A random sample of participants was biochemically validated before birth with hair nicotine, a long-term biomarker of smoke exposure.

RESULTS

Overall, 1181 participants were randomized to intervention (n = 526) and control (n = 655) groups. More participants in the intervention group than the control group reported no SHS exposure 3 months after birth (Total: 77.9% vs. 52.6%, P < .001; Home: 81.2% vs. 53.3%, P < .001). The intervention group also had greater changes in improved smoke-free homes and SHS knowledge and attitudes. Controlling for covariates, the intervention group was less likely to report SHS exposure than the control group (Total: OR = 0.47, 95% CI = 0.31 to 0.71; Home: OR = 0.33, 95% CI = 0.21 to 0.53), and this effect was sustained 3 months after birth. The adjusted log concentration of hair nicotine for the intervention group decreased by 0.28 log µg/g more than the control group.

CONCLUSIONS

Our smoke-free health education intervention for nonsmoking pregnant women significantly reduced SHS exposure before and after birth. This intervention model can become part of a standard protocol for the care of pregnant women in hospital settings.

Randomized trial of a secondhand smoke exposure reduction intervention among hospital-based pregnant women

OBJECTIVE

This study sought to assess the effectiveness of a secondhand tobacco smoke (SHS) prevention program based on an expanded Health Belief Model (HBM) incorporating self-efficacy among pregnant women in a hospital setting in Taiwan.

METHODOLOGY

This study utilized a two-group longitudinal randomized controlled trial design. Participants in the intervention group (n=50) enrolled in a SHS prevention program based on the HBM, while participants in the comparison group (n=50) received standard government-mandated counseling care. Both groups were given questionnaires as a pre-test, two weeks into the intervention, and one month following the conclusion of the intervention. The questionnaire and intervention were developed based on the understanding gained through a series of in-depth interviews and a focus-group conducted among pregnant women. Exhaled carbon monoxide was also measured and used as a proxy for SHS exposure.

RESULTS

Intervention group scores were all significantly higher than comparison group scores (p<0.001), indicating a significant increase in knowledge, HBM scores, cues to action, self-efficacy, preventative behaviors, and a significant decrease in smoking exposure. These differences remained significant at the one-month follow-up assessment (p<0.001).

CONCLUSIONS

These results should encourage health professionals to educate pregnant women regarding the harms of SHS while both empowering and equipping them with the tools to confront their family members and effectively reduce their SHS exposure while promoting smoke-free social norms.

Clinical interventions to reduce secondhand smoke exposure among pregnant women: a systematic review

OBJECTIVE

To conduct a systematic review of clinical interventions to reduce secondhand smoke (SHS) exposure among non-smoking pregnant women.

DATA SOURCES

We searched 16 databases for publications from 1990 to January 2013, with no language restrictions.

STUDY SELECTION

Papers were included if they met the following criteria: (1) the study population included non-smoking pregnant women exposed to SHS, (2) the clinical interventions were intended to reduce SHS exposure at home, (3) the study included a control group and (4) outcomes included either reduced SHS exposure of non-smoking pregnant women at home or quit rates among smoking partners during the pregnancy of the woman.

DATA EXTRACTION

Two coders independently reviewed each abstract or full text to identify eligible papers. Two abstractors independently coded papers based on US Preventive Services Task Force criteria for study quality (good, fair, poor), and studies without biochemically-verified outcome measures were considered poor quality.

DATA SYNTHESIS

From 4670 papers, we identified five studies that met our inclusion criteria: four focused on reducing SHS exposure among non-smoking pregnant women, and one focused on providing cessation support for smoking partners of pregnant women. All were randomised controlled trials, and all reported positive findings. Three studies were judged poor quality because outcome measures were not biochemically-verified, and two were considered fair quality.

CONCLUSIONS

Clinical interventions delivered in prenatal care settings appear to reduce SHS exposure, but study weaknesses limit our ability to draw firm conclusions. More rigorous studies, using biochemical validation, are needed to identify strategies for reducing SHS exposure in pregnant women.

Mental models of pregnancy may explain low adherence to folic acid supplementation guidelines: a cross-sectional international survey

OBJECTIVE

Mental models of pregnancy refer to women's perceptions of whether their pregnancies are susceptible to poor health outcomes. Mental models influence health behaviour during pregnancy. In the present study we examined whether mental models of pregnancy are linked to compliance with folic acid supplementation guidelines.

STUDY DESIGN

Cross-sectional survey implemented in four countries (France, Germany, Belgium, and Poland) of women planning a pregnancy (pregnancy planners, n=325) or within the first 18 weeks of pregnancy (currently pregnant, n=326). Logistic regression was used to examine the association between mental models of pregnancy (i.e. whether women felt susceptible to the health consequences of not taking folic acid supplements), maternal background, and use of folic acid supplements.

RESULTS

Most women (82.8%) had heard of folic acid but only 45.5% were taking folic acid supplements. Use of folic acid supplements did not differ between pregnancy planners and currently pregnant women. Women who believed that they had good general and obstetric health (e.g. no history of illness or miscarriage) and those living in adverse health environments (e.g. smoking, living in poverty) had mental models of being insusceptible to the health consequences of not taking folic acid supplements (p<0.001) and were the lowest users of folic acid supplements (p<0.01). Mediation analyses showed that perceived susceptibility was the common pathway through which the seemingly disparate predictors of folic acid supplementation (i.e. maternal background characteristics) operate.

CONCLUSIONS

Maternal background characteristics may shape women's mental models of pregnancy and its susceptibility to health complications. Mental models could therefore be the common factor explaining poor adherence to folic acid supplementation guidelines. Findings suggest that in the 'invulnerable mum' mental model, perceived susceptibility to health threats is reduced because the good health of the mother is believed to protect the pregnancy from threat, whereas in the 'invulnerable pregnancy' mental model, perceived susceptibility is reduced because pregnancy is viewed as naturally robust or immune to risk. The challenge for the practitioner wanting to increase adherence to periconceptional health advice is to elicit and correct patients' erroneous beliefs about pregnancy.

The effectiveness of breath carbon monoxide analyzer in screening for environmental tobacco smoke exposure in Saudi pregnant women

BACKGROUND:

Exposure to environmental tobacco smoke (ETS) has harmful effects on the pregnancy outcomes similar to those observed in actively smoking pregnant women. The aim of this study was to estimate the sensitivity and specificity of the breath carbon monoxide (BCO) analysis in the assessment of smoking status among Saudi pregnant women, including ETS exposure compared to self-reported tobacco smoke exposure.

METHODS:

A cross-sectional design was used during January 2012, 560 pregnant women, irrespective of their gestational age, agreed to undergo BCO testing and completed the data collection sheet for the study. Sensitivity, specificity, positive and negative predictive values were calculated to compare the BCO test with self-reported exposure to ETS.

RESULTS:

Of the study population 151 (27%) women self-reported ETS exposure during the index pregnancy, 409 (73%) self-reported non-exposure. Sensitivity of the test was 32.5% (95% CI; 25.2-40.3%), the Specificity was much higher at 69.2% (95% CI; 64.4-73.5%), the positive predictive value was 28% (95% CI, 21.9-35.1%), and the negative predictive value was 73.5% (95% CI; 68.9-77.7%).

CONCLUSION:

The BCO test is an ineffective tool to detect the level of ETS exposure among Saudi pregnant women.

Psychosocial interventions for supporting women to stop smoking in pregnancy

BACKGROUND

Tobacco smoking in pregnancy remains one of the few preventable factors associated with complications in pregnancy, stillbirth, low birthweight and preterm birth and has serious long-term implications for women and babies. Smoking in pregnancy is decreasing in high-income countries, but is strongly associated with poverty and increasing in low- to middle-income countries.

OBJECTIVES

To assess the effects of smoking cessation interventions during pregnancy on smoking behaviour and perinatal health outcomes.

SEARCH METHODS

In this fifth update, we searched the Cochrane Pregnancy and Childbirth Group's Trials Register (1 March 2013), checked reference lists of retrieved studies and contacted trial authors to locate additional unpublished data.

SELECTION CRITERIA

Randomised controlled trials, cluster-randomised trials, randomised cross-over trials, and quasi-randomised controlled trials (with allocation by maternal birth date or hospital record number) of psychosocial smoking cessation interventions during pregnancy.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for inclusion and trial quality, and extracted data. Direct comparisons were conducted in RevMan, and subgroup analyses and sensitivity analysis were conducted in SPSS.

MAIN RESULTS

Eighty-six trials were included in this updated review, with 77 trials (involving over 29,000 women) providing data on smoking abstinence in late pregnancy.In separate comparisons, counselling interventions demonstrated a significant effect compared with usual care (27 studies; average risk ratio (RR) 1.44, 95% confidence interval (CI) 1.19 to 1.75), and a borderline effect compared with less intensive interventions (16 studies; average RR 1.35, 95% CI 1.00 to 1.82). However, a significant effect was only seen in subsets where counselling was provided in conjunction with other strategies. It was unclear whether any type of counselling strategy is more effective than others (one study; RR 1.15, 95% CI 0.86 to 1.53). In studies comparing counselling and usual care (the largest comparison), it was unclear whether interventions prevented smoking relapse among women who had stopped smoking spontaneously in early pregnancy (eight studies; average RR 1.06, 95% CI 0.93 to 1.21). However, a clear effect was seen in smoking abstinence at zero to five months postpartum (10 studies; average RR 1.76, 95% CI 1.05 to 2.95), a borderline effect at six to 11 months (six studies; average RR 1.33, 95% CI 1.00 to 1.77), and a significant effect at 12 to 17 months (two studies, average RR 2.20, 95% CI 1.23 to 3.96), but not in the longer term. In other comparisons, the effect was not significantly different from the null effect for most secondary outcomes, but sample sizes were small.Incentive-based interventions had the largest effect size compared with a less intensive intervention (one study; RR 3.64, 95% CI 1.84 to 7.23) and an alternative intervention (one study; RR 4.05, 95% CI 1.48 to 11.11).Feedback interventions demonstrated a significant effect only when compared with usual care and provided in conjunction with other strategies, such as counselling (two studies; average RR 4.39, 95% CI 1.89 to 10.21), but the effect was unclear when compared with a less intensive intervention (two studies; average RR 1.19, 95% CI 0.45 to 3.12).The effect of health education was unclear when compared with usual care (three studies; average RR 1.51, 95% CI 0.64 to 3.59) or less intensive interventions (two studies; average RR 1.50, 95% CI 0.97 to 2.31).Social support interventions appeared effective when provided by peers (five studies; average RR 1.49, 95% CI 1.01 to 2.19), but the effect was unclear in a single trial of support provided by partners.The effects were mixed where the smoking interventions were provided as part of broader interventions to improve maternal health, rather than targeted smoking cessation interventions.Subgroup analyses on primary outcome for all studies showed the intensity of interventions and comparisons has increased over time, with higher intensity interventions more likely to have higher intensity comparisons. While there was no significant difference, trials where the comparison group received usual care had the largest pooled effect size (37 studies; average RR 1.34, 95% CI 1.25 to 1.44), with lower effect sizes when the comparison group received less intensive interventions (30 studies; average RR 1.20, 95% CI 1.08 to 1.31), or alternative interventions (two studies; average RR 1.26, 95% CI 0.98 to 1.53). More recent studies included in this update had a lower effect size (20 studies; average RR 1.26, 95% CI 1.00 to 1.59), I(2)= 3%, compared to those in the previous version of the review (50 studies; average RR 1.50, 95% CI 1.30 to 1.73). There were similar effect sizes in trials with biochemically validated smoking abstinence (49 studies; average RR 1.43, 95% CI 1.22 to 1.67) and those with self-reported abstinence (20 studies; average RR 1.48, 95% CI 1.17 to 1.87). There was no significant difference between trials implemented by researchers (efficacy studies), and those implemented by routine pregnancy staff (effectiveness studies), however the effect was unclear in three dissemination trials of counselling interventions where the focus on the intervention was at an organisational level (average RR 0.96, 95% CI 0.37 to 2.50). The pooled effects were similar in interventions provided for women with predominantly low socio-economic status (44 studies; average RR 1.41, 95% CI 1.19 to 1.66), compared to other women (26 studies; average RR 1.47, 95% CI 1.21 to 1.79); though the effect was unclear in interventions among women from ethnic minority groups (five studies; average RR 1.08, 95% CI 0.83 to 1.40) and aboriginal women (two studies; average RR 0.40, 95% CI 0.06 to 2.67). Importantly, pooled results demonstrated that women who received psychosocial interventions had an 18% reduction in preterm births (14 studies; average RR 0.82, 95% CI 0.70 to 0.96), and infants born with low birthweight (14 studies; average RR 0.82, 95% CI 0.71 to 0.94). There did not appear to be any adverse effects from the psychosocial interventions, and three studies measured an improvement in women's psychological wellbeing.

AUTHORS' CONCLUSIONS

Psychosocial interventions to support women to stop smoking in pregnancy can increase the proportion of women who stop smoking in late pregnancy, and reduce low birthweight and preterm births.