Estimate of the HIV-1 prevalence in pregnant women and effectiveness of zidovudine administered during pregnancy in reducing perinatal transmission

BACKGROUND: Despite the proven efficacy of zidovudine (ZDV) for reducing pe rinatal transmission of HIV-1, questions remain about its implementation an d effectiveness in routine practice. The aims of this study were to assess the impact of ZDV administered during pregnancy in preventing perinatal HIV -1 transmission, and to determine the proportion of early identification of maternal HIV-1 infection over time. PATIENTs AND METHODS: We prospectively followed from birth a cohort of chil dren born between 1/1/1987 and 31/10/1997 to HIV-1-infected mothers. Infant infection status was assessed by follow-up beyond 18 months or HIV-PCR up to 3 months of age. RESULTS: 229 mothers and 248 infants were identified in the cohort. ZDV was administered during pregnancy as monotherapy to 34 mothers for a mean of 4 ,7 (3,1) months prior to delivery. There were no differences In baseline ch aracteristics between the treated and untreated groups. Mean (SD) CD4 cell count was 465 (261) cells x 10(6)/I. Factors associated with transmission w ere a more prolonged time of rupture of obstetric membranes (median 6 vs 1, 04 hours; p = 0,023) and ZDV treatment. Among the ZDV-treated mothers only one child was infected (2,9%), whereas 37 children born to 212 untreated wo men became infected. (OR: 0,14; 95% CI: 0,07-0,92). The estimated prevalenc e of HIV-1 in pregnant women in our area is about 0,39% (95% CI: 0,34-0,45) . From 1987 to 1991, 9,7% of infected women were nor identified at the peri natal period, as compared to 2,5% in the last 5 years of the study period ( p = 0,034). CONCLUSIONS: In this study, the estimated prevalence of HIV-1 infection is high. ZDV during pregnancy is significantly associated with a decrease in p erinatal transmission in our setting. The awareness of an effective treatme nt might have contributed to the increased identification of HIV-infected m others prior to delivery observed over time in our cohort of children born to HIV-infected mothers.