This is a multicenter Phase III study designed to determine whether the vertical HIV transmission rate can be reduced by continuous oral zidovudine administration to HIV-infected pregnant women beginning at 14 to 34 weeks gestation, plus an intrapartum intravenous dose, and continuing in the newborn infant from birth to six weeks of age. The study is also designed to evaluate the safety of zidovudine for both the pregnant woman and for the newborn infant.