Effect of Smoking Cessation on Gestational and Postpartum Weight Gain and Neonatal Birth Weight

OBJECTIVE: To examine the association among smoking cessation, gestational and postpartum weight gain, and neonatal birth weight. METHODS: We analyzed prospectively collected data from 1,774 women with term singleton pregnancies. Smoking status during pregnancy was categorized as nonsmokers, smokers, and quitters; and smoking status 1 year postpartum as nonsmokers, smokers, relapsed quitters, and sustained quitters. The association between smoking status and gestational weight gain, weight gain 1 year postpartum, and neonatal birth weight was tested by linear regression analysis, and the association between smoking status and neonatal birth weight less than the 10th percentile for gestational age and sex was tested by multivariable logistic regression analysis. RESULTS: Gestational weight gain at 16 weeks of gestation was comparable for nonsmokers, smokers, and quitters. The adjusted mean gestational weight gain at 37 weeks of gestation was 2.0 kg (95% confidence interval [CI] 1.5-2.6) higher in quitters compared with nonsmokers. The rate of neonatal birth weight less than the 10th percentile was 21.7% among smokers, 8.0% among quitters, and 7.4% among nonsmokers. The adjusted odds ratio (OR) for birth weight less than 10th percentile was 3.6 (95% CI 2.5-5.2) in neonates born to smokers; the risk was similar for quitters (OR 1.0, 95% CI 0.6-1.6). One year after delivery, sustained quitters had a 2.4-kg (95% CI 1.6-3.1) higher adjusted postpartum weight gain than nonsmokers. CONCLUSION: Smoking cessation is associated with gestational as well as postpartum weight gain. However, smoking cessation is associated with a substantially lower rate of neonatal birth weight less than the 10th percentile.