Shortly after birth, infants will receive single-dose NVP. A 1-month supply of ZDV will be provided to the mother to administer daily to her child. Mothers will stop HAART at 6 months postpartum or when they stop breastfeeding, whichever occurs earlier. A clinical evaluation, blood collection, and HIV prevention counseling will occur at all maternal visits. An obstetrical exam and physical exam will occur at selected visits. Women will provide at least four samples of breast milk during the first 5 months postpartum. For infants, a clinical evaluation will occur at every visit, and a physical exam and blood collection will occur at selected visits.