An estimated 30 percent to 40 percent infected pregnant women risk transmission of HIV-1 to their infants, whether they be symptomatic or asymptomatic. Zidovudine (AZT) has previously demonstrated its effectiveness as a potent inhibitor of HIV replication in vitro and in adult patients; benefits of treatment include decreased mortality rate, decreased incidence of opportunistic infections, and increased number of CD4 cells. Phase I AZT studies in children, however, have resulted in uncontrolled information regarding clinical efficacy. The present study, therefore, will investigate the safety and pharmacokinetics of intravenous (IV) and oral AZT administration to HIV-1 infected pregnant women in the 3rd trimester, as well as the safety and efficacy of such treatment in their newborns.