Associations of maternal obesity and smoking status with perinatal outcomes.

Maternal obesity and smoking are associated with adverse perinatal outcomes. These prevalent conditions contribute to health disparities. In this study, we examine whether maternal BMI moderates the impact of smoking cessation on short-term perinatal outcomes. This is a secondary analysis of assessments conducted from several prospective clinical trials examining the efficacy of incentives to promote smoking cessation during pregnancy. Participants were randomly assigned to receive financial incentives contingent upon smoking abstinence or a control condition. Pregnancy outcomes were abstracted from the medical record. ANCOVA and multiple logistic regression were used for statistical analysis. Among 388 women, there was a significant interaction between maternal pre-pregnancy BMI and smoking status on gestational age at delivery (p = .03) and admission to the NICU (p = .04). Among underweight/normal weight gravidas, smoking resulted in earlier deliveries and a greater likelihood of NICU admission than in those who abstained. Among overweight/obese gravidas, there was no effect of smoking on gestational age at delivery and infants of smokers were less likely to be admitted to the NICU. Maternal obesity and smoking have significant individual effects on perinatal outcome. Maternal overweight/obesity appears to moderate the effect of smoking on gestational age at delivery and on NICU admissions.