Infants receive a single oral dose of NVP (or the corresponding placebo) administered between 48 and 72 hours of life. The infant's study drug is the same as the mother's randomized treatment assignment. Infants are dosed with study drug according to their randomization group regardless of whether the mother received study drug or not. Infants are followed for 6 months of life and are tested for HIV at birth, 4 to 6 weeks of life, 3 months of life, and 6 months of life.