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Systematic Review
The aim of this report is to review the clinical effectiveness of smoking reduction programs and smoking cessation interventions for pregnant women and mothers of infants.
Question 1. What is the clinical effectiveness of smoking reduction programs for pregnant women or mothers of infants? One trial was identified that assessed a home visitation program by trained nurses to help young pregnant women with a low education level in reducing cigarette smoking and promoting breastfeeding. The percentages of smokers in both intervention and control groups were not significantly different at either 32 weeks of pregnancy (33% vs 35%) or at two months after childbirth (48% vs 65%). After conducting the last observation carried forward approach to correct for missing data, the percentages of smokers in the intervention group were significantly lower than those in the control group; 40% versus 48% at 32 weeks of pregnancy, and 49% versus 62% at two months after childbirth. There was no difference in the number of cigarettes smoked per day between the intervention and control groups (2 versus 3 cigarettes) at 32 weeks of pregnancy, although the numbers of cigarettes smoked in both groups reduced compared to those at enrolment (7 versus 8 cigarettes). At two months after birth, women in the control group increased their daily cigarettes smoked as of at baseline (8 cigarettes), while women in the intervention group smoked an average of 4 cigarettes per day. Birth weight, gestational age, the prevalence of low birth weight (i.e., <2,500 g), and the prevalence of premature babies (i.e., <37 weeks) were similar in both groups.
Question 2. What is the clinical effectiveness of smoking cessation interventions for pregnant women or mothers of infants?One SR and three RCTs were identified that reported relevant outcomes for the psychosocial interventions, and one SR and one RCT were identified that reported relevant outcomes for pharmacological interventions. There was evidence from the SR that counselling was more effective than usual care or less intensive intervention. It was uncertain about the effectiveness of counselling (i.e., cognitive behavioral therapy) compared with alternative intervention (i.e., health education or motivational interview).
Pharmacological interventions: There was evidence that NRT increased the rates of biochemically validated smoking cessation by about 40% compared to the control group. However, there was no difference in the self-reported smoking abstinence rates between NRT and the control group at 3, 6 or 12 months postpartum. Bupropion sustained release increased abstinence rates during treatment compared to placebo, but there was no significant difference in the abstinence rates between groups at the end of treatment, at the end of pregnancy, and during the postpartum period.
There was limited evidence on the effectiveness of smoking reduction interventions, and it was unclear if a nurse home visitation program was effective in helping pregnant women to reduce smoking. There was strong to moderate evidence that suggested that psychosocial interventions for promoting smoking cessation during pregnancy can increase the proportion of women who stopped smoking in late pregnancy. Among the psychosocial interventions, counselling, feedback, and incentives appeared to be effective, while the effect of health education and social support was less certain. Counselling and incentives appeared to be effective for continued abstinence during the postpartum period. It was unclear if smoking cessation interventions can help pregnant women to reduce smoking. Pooled results suggested that psychosocial interventions reduced the risk of infants born with low birthweight, increased the mean birthweight, and decreased the risk of NICU admission. Pharmacological interventions, such as NRT and bupropion, appeared to be effective only during treatment or in late pregnancy, but not after pregnancy or during postpartum period. There was no evidence that NRT had any positive or negative effect on infant outcomes and the safety of bupropion was less clear. More evidence is needed, particularly, on the programs promoting smoking reduction for pregnant women, and on the effectiveness and safety of smoking cessation drugs, such as bupropion, varenicline, or other medications for pregnant smokers.