Giving anti-HIV medications to babies born of HIV positive mothers right after birth can lower the babies' risk of contracting HIV. This study will assess the safety and efficacy of two different combinations of anti-HIV medications compared to a one drug standard regimen in preventing mother to baby transmission. The one drug standard treatment and two combinations to be studied are: 1) zidovudine, 2) zidovudine/nevirapine and 3) zidovudine/lamivudine/nelfinavir.

Despite the notable reductions in perinatal transmission of HIV-1 with antiretroviral therapy and other interventions, perinatal transmission continues to occur at rates of 20-30% among pregnant women who are not identified as HIV-1-infected and/or are not provided with antiretroviral therapy. The optimum treatment strategy for prevention of transmission of HIV-1 to infants born to these women is unknown. No trials have evaluated the efficacy of neonatal antiretroviral therapy alone but observational data suggest benefit from zidovudine (ZDV) therapy given to the infant beginning within 48 hours of birth and continued for six weeks. This protocol will compare the safety and efficacy of three antiretroviral regimens administered in the neonatal period: Arm A- ZDV, Arm B- ZDV plus nevirapine (NVP), and Arm C- ZDV plus nelfinavir (NFV) and lamivudine (3TC). Two regimens were selected based on expected antiretroviral activity, pharmacokinetic data, and toxicity profiles. Standard of care (6 weeks of ZDV) alone will be compared to the 6 weeks of ZDV plus either 3 doses of NVP or 2 weeks of 3TC and NFV. Arm B (ZDV + NVP) is the regimen expected to provide the best profile when factors of efficacy, safety, cost, acceptability and convenience are considered. The comparison of Arms B and C is also of considerable interest since the 2-drug Arm B is easier to implement and less expensive than the triple drug Arm C. Although triple drug therapies have been recommended for post-exposure prophylaxis for needle-stick injuries in high-risk circumstances, it is unknown whether the triple drug arm will provide better efficacy than the 2-drug arm for post-exposure prophylaxis of the infant.

This open-label study is expected to accrue 1731 infants of women identified in labor as being HIV positive or who are HIV positive but have not received antiretroviral medication during the pregnancy. If eligible the infant will be randomized at birth to one of three aforementioned treatment arms. Medical history, social, demographic, physical exam, RNA and T- lymphocyte data are collected on the mother during the delivery visit. The infant will have a birth visit and then return for 1-week, 2-week, 4-week, 3-month and a final 6-month visit. Infant evaluations will include: a medical history and physical exam, DNA testing, CBC and liver function tests, cells for long-term storage and RNA/CD4/CD8 testing if HIV positive. The initial study drug doses will be given to the infant while in the hospital. Mothers will administer the infants' remaining treatment doses at home depending on ability.

Inclusion Criteria:

Infants who meet all of the following criteria are eligible for the study:

• Mother known to be HIV-1-infected prior to labor or identified at the time of labor or <48 hours postpartum. HIV-1 infection for the purposes of enrollment into this study is defined as: (a) Single positive HIV-1 rapid test in mother or her infant; or (b) Historical documentation of a positive HIV-1 diagnostic test confirmed by repeat diagnostic testing for HIV-1 according to country guidelines in mother (written documentation of test results must be present in the medical record).
• Maternal written informed consent for study participation.
• Mother has not received any antiretroviral therapy during the current pregnancy prior to the onset of labor and delivery; women may have received intravenous or oral ZDV during labor. Women may have received any antiretroviral therapy in previous pregnancies for prevention of vertical HIV-1 transmission.
• Infant is <48 hours old. Infant may have received up to 48 hours of ZDV as standard care before study enrollment.

Exclusion Criteria:

Infants who meet any of the following criteria will be excluded from the study:

• Extreme prematurity (< 32 weeks of gestation).
• Birth weight <1500 grams.
• Presence of life-threatening conditions.
• Inability to take oral medication throughout the first 48 hours of life (must be able to receive oral medication by age 48 hours).
• Maternal inability to provide informed consent because of a lack of a conscious state, psychiatric conditions, or language barriers.
• Mother received any antiretroviral therapy during labor and delivery other than intravenous or oral ZDV.