 The increase in pediatric HIV infection has a substantial impact on childhood mortality in the developing world. A number of recent studies suggest that as many as half or more of mother-to-child HIV transmissions in developing countries occur in late pregnancy or during labor and delivery. Interventions targeted during the perinatal period have shown to be effective and to have a significant impact in reducing transmission. The purpose of this study is to investigate the effectiveness of nevirapine NVP plus immunoprophylaxis or extended NVP dosing regimens in HIV-infected pregnant women and their infants during the perinatal period. 