Moderate alcohol use during pregnancy and decreased infant birth weight.

Maternal alcoholism during pregnancy may result in severe prenatal growth deficiency. In this prospective study, the relationship of moderate maternal alcohol consumption to infant birth weight is explored. Subjects were 263 paying members of a health maintenance organization who delivered single live children. Their alcohol consumption before pregnancy, and in early and late pregnancy, was estimated. In order to control for smoking, which is strongly related to both infant birth weight and maternal alcohol use, the sample was selected so that similar proportions of smokers were represented in both light and heavier drinkers. Multiple linear regression was employed. A regression equation was computed for each of the three periods in which drinking was estimated. Independent variables entered into the equation were maternal age, height, parity, daily cigarettes, alcohol use in the period, and gestational age and sex of child. The regression of birth weight on these variables revealed a significant relationship (p less than or equal to .01) with alcohol consumption in two of the periods. Ingestion of an average of one ounce of absolute alcohol daily before pregnancy was associated with an average decrease in birth weight of 91 grams; the same amount ingested in late pregnancy was associated with a decrease of 160 grams. The associations were independent of the other variables entered into the equation, and in particular, of tobacco use.