Disturbed sleep regulation is often observed in neonates of women who drank heavily during pregnancy. It is unknown if (and how) an occasional drink affects fetal sleeping behavior. In 28 near-term pregnant women we examined the effects on fetal behavioral state organization of two glasses of wine (0.25 g of ethanol/kg of maternal body weight). Simultaneous 2-h recordings of fetal heart rate and body, eye, and breathing movements were made on two successive days, once without alcohol exposure and once during maternal alcohol consumption. The study was standardized for time of day and fetal sleep state, i.e. the start of recording was either during quiet sleep (n = 16) or during active sleep (n = 12). Alcohol intake reduced fetal eye movements, disorganized behavioral state organization (rapid eye movement sleep was affected in particular), and suppressed fetal breathing activity almost completely. Modest maternal alcohol intake affects fetal behavioral state organization, which reflects an immediate effect on fetal brain function.