Maternal drinking behavior and decreased intrauterine growth.

Reduced intrauterine growth has been a widely observed effect of maternal alcohol use during pregnancy in both animals and humans, although results in studies of humans have been inconsistent. The goal of this prospective study was to evaluate the relative importance of volume, frequency, and beverage source of alcohol as determinants of infant birthweight, while adjusting for other known determinants using multivariate techniques. In a sample of 5,093 maternal-infant pairs, 44 potential determinants of intrauterine growth were evaluated. The frequency of beer drinking, controlled for wine drinking, liquor drinking, and other variables, was found to contribute independently to a reduction of intrauterine growth, as measured by birthweight adjusted for gestational age. Of the variables explored, 11, including cigarette smoking and caffeine intake, were found to contribute significantly (R2 = 32%; p less than 0.001) to the variance. The effect of beer drinking was most apparent in the most frequently drinking 3% of gravidas. These results appear to confirm a previous suggestion that heavy beer drinking during pregnancy is related to decreased intrauterine growth, but should be interpreted cautiously since there are several alternative explanations for the finding. Thus, these results suggest several areas for further investigation.