Breastfeeding provides general health, growth, and development benefits to an infant and significantly decreases the risk of certain acute and chronic diseases. Breastfeeding also decreases financial burden on the mother by decreasing the need for infant formula and health care for the infant. However, clinical evidence has shown that HIV can be readily transmitted through breast milk, although the risk of HIV MTCT over time while breastfeeding has been difficult to determine. Given the many advantages of breastfeeding and the significant obstacles to substituting formula for breast milk in developing countries, there is an urgent need to make breastfeeding by HIV infected women safe. This study will evaluate the safety and efficacy of an extended NVP regimen for prevention of MTCT of HIV through breastfeeding.