Recent research on the effects of alcohol use during pregnancy indicate that discontinuing alcohol use mid-pregnancy can prevent or minimize many of the adverse consequences usually observed in the children of women who consume alcohol throughout pregnancy. Few studies have examined the contributions of maternal dose level independent of the duration of drinking during pregnancy. In this study the effects of prenatal dose (volume of maternal alcohol use per week during pregnancy) and duration (exposure throughout pregnancy vs. exposure in the first and second trimesters only) on newborn physical and behavioral development were examined. Dependent measures were cluster scores on the Brazelton Neonatal Behavioral Assessment Scale (BNBAS) at three days, infant birthweight, length, and head circumference. Subjects were infants of obstetric patients at Grady Memorial Hospital in Atlanta who were participating in a study on the effects of alcohol use during pregnancy on infant outcome (n = 149). Subjects were primarily black and of low socioeconomic status. Infants of women who continued to drink throughout pregnancy differed from those of women who did not drink during pregnancy on orientation, (the ability to attend to environmental stimuli), p less than 0.05, autonomic regulation, p less than 0.0002, birthweight, p less than 0.04, length, p less than 0.01, and head circumference, p less than 0.01. Both prenatal alcohol dose, p less than 0.03, and the duration of alcohol exposure, p less than 0.03, independently affected autonomic regulation. A significant interaction was found for birthweight, p less than 0.02, with independent main effects for both dose and duration of exposure, p less than 0.01.(ABSTRACT TRUNCATED AT 250 WORDS)