This is an analysis of the effect of prenatal alcohol exposure on growth of the offspring at 18 months of age. In this prospective study, a cohort of women was interviewed at the end of each trimester of pregnancy, at delivery, and at 8 and 18 months. Offspring were examined at each follow-up point. Two drinking scales, average daily volume (ADV) and frequent heavy drinking (FHD), were used to explore the effect of different patterns of drinking. We found significant relationships between both prenatal FHD and ADV and offspring growth at 18 months. A significant and inverse relationship was found between ADV during the second and the third trimesters of pregnancy and weight, height, and head circumference at 18 months. Frequent heavy drinking during all three trimesters predicted a significant decrease in head circumference at 18 months. FHD during the second trimester was significantly related to weight and height at 18 months. Analyses demonstrated that ADV was a better predictor of growth deficits than FHD.