Changes in the content and structure of social relationships following the birth of the first child were studied with a non-probability sample of primiparous couples. Differences between men and women were examined regarding changes in network structure, need for support, satisfaction with available support, access to support from network members, and stress and conflict in relationships with network members. In total, 108 subjects responded to investigator-developed tools during the third trimester of pregnancy, 92 subjects at 5 months postpartum, and 69 subjects at 8 months postpartum. More women than men perceived an increased need for support postpartum, but no differences in satisfaction with available support existed. For men, network size decreased, but the percentage of network members with preschool children, the percentage of members offering emotional support, and the boundary density with wives' networks all increased. Women reported decreased frequency of contact with coworkers, but increased frequency with friends, and, as did fathers, named more members with preschool children.