This paper reports the results of a prospective investigation of 100 women during their pregnancies to test the hypothesis that social and psychological factors influence pregnancy outcome after controlling for demographic, biomedical, and lifestyle variables. Subjects completed questionnaires that assessed family social supports, life events, and anxiety. In addition, data were collected on general biomedical and pregnancy risk, lifestyle practices including smoking and drinking, as well as demographic information. Four infant outcomes, birthweight, gestational age, and 1 and 5 min Apgar scores, were studied via hierarchical multiple regression analyses for their relationship to the social and psychological variables, after controlling for all other sets of variables. The results of these analyses showed that life events stress accounted for significant variation in birthweight, and social supports and anxiety were associated with the two pediatric Apgar scores. Gestational age bore a simple relationship to anxiety, with higher anxiety predictive of lower gestational age. Further analyses revealed that women with either low social supports or high anxiety were, on the average, younger, more often single, of lower education level, had less income, smoked more, and had higher general biomedical risk than women with adequate social supports or lower anxiety. This suggests the multiple ways in which social and psychological risk factors may be related to pregnancy outcome and emphasizes the need for well controlled studies in this area.