EFFICACY OF ANTENATAL ZIDOVUDINE IN REDUCING PERINATAL TRANSMISSION OF HUMAN-IMMUNODEFICIENCY-VIRUS TYPE-1

New York City women (321) enrolled during 1986-1993 in an observationa l cohort study were analyzed retrospectively to determine the effectiv eness of antenatal zidovudine in reducing perinatal transmission of hu man immunodeficiency virus type 1 (HIV-1) in women with various CD4(+) lymphocyte counts (<200, 200-499, >499/mu L). When CD4(+) lymphocyte level was controlled for, women prescribed zidovudine during pregnancy were less likely to transmit HIV-1 to their infants (adjusted odds ra tio, 0.36; 95% confidence interval, 0.14-0.92), There was no conclusiv e evidence that efficacy of zidovudine depended on CD4(+) lymphocyte l evel, suggesting that women with severe CD4(+) cell depression, who ar e at highest risk of transmitting HIV-1, may also benefit from zidovud ine. Antenatal zidovudine treatment alone may substantially lower the risk of perinatal HIV-1 transmission. These data are consistent with t he results of AIDS Clinical Trial Group protocol 076 and suggest that a substantial portion of zidovudine's protective effect may occur when used during the antenatal period.