Although administration of ZDV to mother-infant pairs has dramatically reduced perinatal HIV infection, the goal is to reduce it further to less than 2%. In order to achieve this, combination strategies need to be developed for 2 purposes: 1) to reduce the perinatal transmission rate to goal levels; and 2) to provide other combination therapies for HIV-infected mothers whose virus has become resistant to ZDV, who have a very high viral load, or who have previously transmitted HIV while on ZDV. This study adds 3TC (another reverse transcriptase inhibitor) and SQV (a protease inhibitor [PI]) [AS PER AMENDMENT 08/15/00: with low-dose RTV (another PI)] to the mother's ZDV regimen.

During the antepartum period, mothers receive SQV with [AS PER AMENDMENT 08/15/00: low-dose RTV plus] ZDV and 3TC. At onset of active labor, mothers receive loading doses of each of the study drugs, then receive study drugs for 12 weeks postpartum on the same schedule as during the antenatal period. Within 12 hours of delivery, infants begin receiving 3TC and ZDV and continue until 6 weeks of age. Mothers are followed until 12 weeks postpartum and babies are followed until 6 months of age. [AS PER AMENDMENT 02/09/99: For maternal dosing, 1 Combivir tablet (containing 3TC and ZDV) may be administered in place of the individual agents 3TC and ZDV. Patients who prematurely discontinue study treatment should continue to be followed for the duration of the study.]