Though the reported experience with zidovudine in human pregnancies is very limited, it would seem unreasonable at this time to withhold zidovudine therapy for fetal considerations in the treatment of pregnant women with AIDS and ARC. Whether the treatment of HIV-positive women with zidovudine at any time during pregnancy reduces the risk of perinatal transmission is unknown. Therefore, the use of zidovudine for that indication should await the results of controlled trials. At present, if zidovudine therapy is required during pregnancy, the standard dosage of 200 mg every 4 hours should be used. The woman and her fetus should be monitored carefully for signs of toxicity.