PREVENTION OF VERTICAL HIV TRANSMISSION WITH ZIDOVUDINE - PROJECTED IMPACT OF HIV TESTING AND PRENATAL-CARE

We sought to estimate the impact of maternal HIV testing and prenatal care on the potential to reduce vertical transmission through zidovudi ne (AZT) use by HIV-infected mothers. We evaluated the prepartum mater nal HIV diagnosis rate, prenatal care, disease stage, and vertical tra nsmission rate (from a two-part mixture model) using New York State Me dicaid and vital statistics data for HIV-infected mothers and their si ngletons in 1985-90. We used published data to estimate the effect of AZT on vertical transmission and expert input to define other paramete rs for the model. Our HIV-infected (N=1514) had a vertical transmissio n rate of 27.0%. HIV was diagnosed prepartum for 39.5% of women in 199 0. Transmission would have been 22.2% if AZT had been taken only by th e subset of women diagnosed prepartum with HIV and receiving prenatal care by 34 weeks gestation (86.7%). Transmission would have dropped to 11.2% if all women had been diagnosed prepartum with HIV and received adequate prenatal care. The observed deficiencies in prenatal care an d maternal HIV diagnosis rates in this Medicaid population-based cohor t must be addressed to realize the promise of AZT to reduce vertical t ransmission.