A Study of Zidovudine/Lamivudine and Either Nevirapine or Nelfinavir for Reduction of Mother-to-child HIV Transmission During Breastfeeding (KiBS)

Inclusion Criteria: Be a pregnant HIV-infected female presenting prior to 34 weeks gestation who has already chosen to breastfeed after receiving counseling on infant feeding choices according to UNAIDS guidelines which includes counseling and education about the overall benefits of breast feeding as well as the risks of HIV transmission to the infant inherent in breastfeeding. Report that they plan to reside in Kisumu for the next 2 years Be able to give competent, informed consent if >18 or have a parent or guardian who can do the same in the case of a minor. Be willing to comply with study requirements if they meet study eligibility criteria. Meet the following laboratory criteria at enrollment (Efforts will be made to address potentially correctable abnormalities such as anemia, prior to enrollment) Documentation of HIV-1 infection according to the Kenyan National PMCT testing algorithm. Serum creatinine <1.5 mg/dl Hgb >7.0 g/dL Absolute neutrophil count > 1000 cells/ml Platelet count >50,000/ml SGPT < 2.5 times upper limit of normal Documentation of CD4 count results prior to beginning study drug; which will be used to determine the appropriate HAART regimen -i.e ZDV/3TC/NVP or ZDV/3TC/NLF Documentation of Hepatitis B and C infection status (Hepatitis B surface antigen and Hepatitis C antibody) Have signed consent and met clinical and laboratory eligibility criteria in order to be enrolled in the trial by 34-36 weeks gestation (preferably at 34 weeks). Exclusion Criteria: Is participating in other HIV vaccine or antiretroviral trials. Has substantial hypersensitivity to any benzodiazepine, including Nevirapine. Has history of prior substantial intolerance or severe allergic reaction to Nevirapine, Zidovudine, Lamivudine or Nelfinavir. For women who will be placed on NVP, ongoing treatment with rifampin, anticoagulants, benzodiazepines, and magnesium sulfate at time of planned enrollment. For those women who will be placed on NLF, ongoing treatment with amiodarone, quinidine, ergot derivative drugs, rifampin, pimozide, St John's work, lovastatin, simvastatin, midazolam or triazolam Has evidence of clinically significant cardiac, respiratory, hepatic, gastrointestinal, endocrine, hematologic, psychiatric, neurologic, or allergic disease that would compromise the ability of the participant to complete the study or the study requirements as determined by the principal investigator or designated associate. The clinical significance of any abnormality is to be evaluated in the context of the safety of the patient volunteer and the objectives of this study. Has a history of cytotoxic chemotherapy within one month prior to study entry or current diagnosis of malignancy for which systemic therapy is expected to be required during the period of study. Blood pressure > 160 mm Hg systolic or > 110 mm Hg diastolic. Chronic alcohol or illicit drug use. Women who become pregnant again during the study follow-up will NOT be eligible for re-enrollment in the trial if they were enrolled for their previous pregnancy.