The major effects of maternal alcohol use during pregnancy are decreased fetal growth, morphologic abnormalities, and CNS impairment. If all three of these are present, with a characteristic facies in the infant, fetal alcohol syndrome (FAS) is diagnosed. FAS occurs only with heavy or alcoholic drinking. The individual components of the syndrome exhibit a dose-response association with ethanol intake in many, but not all studies. Discrepancies in maternal drinking and pregnancy outcome reflect the myriad difficulties of these investigations. Drinking "before" pregnancy also has been linked to decrements in fetal development, possibly because before pregnancy may include the periconceptional period. However, women who are usually abstainers before pregnancy appear to have infants at higher risk of some adverse pregnancy outcomes than women who are light drinkers. Future studies need to construct careful drinking histories to address this and other questions that deal with parents' ethanol use and reproductive health.