Prenatal alcohol consumption and fetal growth restriction: Potentiation effect by concomitant smoking

INTRODUCTION: This study investigates whether maternal cigarette smoking modifies the association between alcohol use in pregnancy and the risk of small-for-gestational-age (SGA) delivery. METHOD: We employed linked vital statistics data of singleton births in the state of Missouri covering the period 1989 through 1997 (N = 655,758). Multivariate logistic regression was used to generate adjusted odds ratios (AORs) and 95% confidence intervals (CIs) for SGA associated with maternal alcohol intake. A subanalysis was conducted to assess the impact of the interaction of alcohol consumption and tobacco use on SGA. RESULTS: About 2% of mothers (n = 14,444) reported consuming alcohol during pregnancy, and approximately 4% of SGA births occurred among these mothers. Women who consumed alcohol during pregnancy had a 20% greater risk for delivering an SGA infant than mothers who abstained (AOR = 1.2; CI = 1.1-1.3). The relative risk for SGA birth rose as the reported number of drinks consumed per week increased (trend p < .0001). The relative risk of delivering an SGA infant was consistently higher among women who reported both drinking alcohol and using tobacco products in pregnancy as compared to women who were drinkers but nonsmokers. The greatest risk was among women who smoked and consumed five or more drinks per week (AOR = 4.8, CI = 4.2-5.5). DISCUSSION: Our findings suggest significant interaction between prenatal alcohol consumption and smoking on the risk of delivering an SGA infant and highlight the relevance of developing "dual message" health education programs that would stress the deleterious effect of joint exposure to alcohol and nicotine in pregnancy.