While perinatal HIV infection has become rare in developed countries through the use of highly active antiretroviral therapy (HAART), it remains a serious problem in developing countries. Botswana has a population of approximately 1.7 million; the prevalence of HIV in Botswana is about 37.4%. In the developed world, HAART has revolutionized the prevention of MTCT among nonbreastfed infants. This trial will compare the effectiveness of a protease inhibitor (PI)-based regimen versus a triple nucleoside reverse transcriptase inhibitor (NRTI)-based regimen in preventing MTCT of HIV.