Anti-HIV drug regimens have dramatically improved the rates of prevention of mother-to-child transmission (MTCT) of HIV in developed countries. However, little is known of the effectiveness of such regimens in developing countries, such as Botswana. This study will determine whether Trizivir (TZV), a single pill containing abacavir sulfate, lamivudine, and zidovudine (ABC/3TC/ZDV), or lopinavir/ritonavir (LPV/r) and lamivudine/zidovudine (3TC/ZDV) is more effective in reducing HIV-1 viral load and preventing MTCT among HIV infected pregnant women in Botswana.