Prenatal depression has been linked to adverse reproductive outcomes including preterm labor and delivery, and low birth weight. Social support also has been linked to birth outcomes, and may buffer infants from the adverse impact of maternal depression. In this prospective study, 235 pregnant women completed questionnaires about depression and social support. Clinical interviews were administered to assess for DSM-IV axis I disorders. Following delivery, birth outcomes were obtained from medical records. Babies of depressed mothers weighed less, were born earlier and had lower Apgar scores than babies of nondepressed mothers. Depressed women had smaller social support networks and were less satisfied with support from social networks. We found no direct associations between perceived social support and birth weight. However, depressed women who rated their partners as less supportive had babies who were born earlier and had lower Apgar scores than depressed mothers with higher perceived partner support. Women’s perception of partner support appears to buffer infants of depressed mothers from potential adverse outcomes. These results are notable in light of the low-risk nature of our sample and point to the need for continued depression screening in pregnant women and a broader view of risk for adverse birth outcomes. The results also suggest a possible means of intervention that may ultimately lead to reductions in adverse birth outcomes.