 This is a three-arm randomized, open label, clinical trial to evaluate the effectiveness of two extended regimens of antiretrovirals compared to infant single dose nevirapine plus AZT given twice daily for 1 week comparison regimen. All infants receive the comparison regimen at birth and then randomized at birth to start either one of the two extended regimens after the first week. The extended regimens are nevirapine daily and nevirapine plus AZT daily - both regimens are given up to age 14 weeks. 