Background: Smoking remains one of the few potentially preventable factors associated with low birthweight, very preterm birth and perinatal death.
Objectives: The objective of this review was to assess the effects of smoking cessation programs implemented during pregnancy on the health of the fetus and infant, on the mother and on the family.
Search strategy: We searched the Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Tobacco Addiction Group trials register.
Selection criteria: Randomised and quasi-randomised trials of smoking cessation programs implemented during pregnancy.
Data collection and analysis: Trial quality was assessed and data were extracted independently by two reviewers.
Main results: Forty-four trials were identified: 37 trials including 16,916 women provided data on smoking cessation and/or perinatal outcomes, as did one cluster-randomised trial including 3000 women. Over 800 women were included in trials of smoking relapse prevention. There was substantial variation in the intensity of the intervention and the extent of reminders and reinforcement through pregnancy. Based on 34 trials there was a significant reduction in smoking in the intervention groups (odds ratio 0.53, 95% confidence interval 0. 47 to 0.60), an absolute difference of 6.4% women continuing to smoke. The eight trials with validated smoking cessation, a high intensity intervention and a high quality score had an odds ratio of 0.53, 95% confidence interval 0.44 to 0.63 and an absolute difference in continued smoking of 8.1%. The subset of trials with information on fetal outcome revealed a reduction in low birthweight (odds ratio 0.80, 95% confidence interval 0.67 to 0.95), a reduction in preterm birth (odds ratio 0.83, 95% confidence interval 0.69 to 0. 99) and an increase in mean birthweight of 28g (95% confidence interval 9 to 49). There were no differences in very low birthweight or perinatal mortality. Five trials of smoking relapse prevention showed no significant difference. The single large cluster-randomised trial showed no evidence of a decrease in continued smoking or adjusted mean birthweight.
Reviewer's conclusions: Smoking cessation programs in pregnancy appear to reduce smoking, low birthweight and preterm birth, but no effect was detected for very low birthweight or perinatal mortality.