The Effect of Maternal Alcohol Consumption on Fetal Growth and Preterm Birth

Although numerous studies have investigated the effects of alcohol intake during pregnancy, currently available data linking prenatal alcohol exposure with abnormal fetal growth or preterm birth are inconclusive. This population-based cohort study assessed the effects of prenatal exposure to alcohol via a questionnaire given to a 10% random sample of all nonindigenous women in Western Australia who had delivered a singleton infant (n = 4719) between 1995 and 1997. The investigators examined the quantity of alcohol consumed per occasion, the frequency of consumption, and the total quantity consumed during the 3 months before and during each trimester of pregnancy. Multivariate logistic regression analysis was used to assess the possible association between alcohol consumption, both before and during pregnancy, with abnormal fetal growth (both small-for-gestational-age [SGA] and large-for-gestational-age infants [LGA]), and with preterm birth (<37 weeks of gestation). The control group consisted of infants born to abstinent women. In unadjusted analysis, moderate to heavy alcohol consumption during pregnancy was associated with an increased proportion of SGA infants born preterm. Adjustment for smoking status eliminated this effect in SGA infants. Binge drinking, defined as 5 or more drinks per occasion, in the first trimester was associated with a nonsignificant increase in the odds of preterm birth (adjusted odds ratio [aOR], 1.31; 95% confidence interval [CI], 0.67–2.58) as was binge drinking in late pregnancy (aOR, 1.61; 95% CI: 0.68–3.77). Compared to the controls, women with moderate and heavy alcohol consumption had a significantly increased risk of preterm birth only if they ceased drinking before the second trimester (aOR 1.78; 95% CI: 1.01–3.14). Low levels of alcohol intake during pregnancy (less than 60 gm/week or two or less standard drinks per occasion) was not associated with preterm birth or SGA. These findings suggest that heavy and binge drinking among pregnant women may increase the likelihood of preterm birth, although the small number of patients makes the significance of these data unclear.