Women receive nelfinavir plus 3TC plus ZDV antepartum (Study Day 0 until onset of active labor) through postpartum (after cord clamped to 12 weeks). [AS PER AMENDMENT 10/28/97: If patient presents in active labor with less than 1 hour to delivery time, the institutional protocol for ZDV infusion during labor should be followed.] [AS PER AMENDMENT 1/26/99: For maternal dosing, one Combivir tablet bid can be substituted for the individual formulation of 3TC and ZDV. For mothers who receive Combivir during the antepartum period, Combivir is held during labor and delivery, and the separate formulations of ZDV and 3TC are used. Patients who prematurely discontinue study treatment should continue to be followed on study for the duration of the study.] Full pharmacokinetic sampling is performed 10 to 15 days after start of therapy [AS PER AMENDMENT 2/7/00: 10 to 15 days after study entry for women currently taking nelfinavir] and again 5 to 6 weeks after delivery. A maternal blood sample and cord blood sample is collected at birth for analysis of nelfinavir concentrations. Maternal HIV RNA in plasma is monitored throughout the study. Cervicovaginal secretions are collected at entry, late gestation, and postpartum to assess the presence of HIV. A single pharmacokinetics sample is collected with each cervicovaginal secretion. Serial CD4/CD8 activation markers are measured in women during gestation and postpartum. Infants receive nelfinavir plus 3TC plus ZDV beginning approximately 12 hours following birth and continuing for 6 weeks. After birth, several blood samples are collected from the infant for determination of washout kinetics of nelfinavir. Full pharmacokinetics sampling is performed 5 to 8 days post birth and 5 to 6 weeks following multiple doses. Pharmacokinetic samples are analyzed on the first six mother-infant pairs and dosing may be adjusted accordingly for the next cohort. Agouron has agreed to make nelfinavir available to all interested study participants for a period of 6 months after the study via the patient assistance program.