AMENDED: To evaluate the pharmacokinetics of intravenously administered AZT to HIV-1 infected pregnant women in labor; to evaluate the pharmacokinetics and urinary excretion of AZT and its metabolites in newborns of HIV-1 infected mothers who receive IV AZT only during labor; to evaluate the safety of IV AZT administered by continuous infusion to HIV-1 infected laboring women and their infants. Original design: To determine the distribution and elimination of zidovudine (AZT) in the body as well as its safety in the treatment of pregnant women and their unborn children. The information derived from this study is required in order to design a future study that will assess the efficacy of AZT in reducing the transmission rate of HIV-1 from seropositive women to their fetus by treating them during the third trimester of pregnancy.