Administration of zidovudine during late pregnancy and delivery to prevent perinatal HIV transmission -- Thailand 1996-1998.

The efficacy of a short-term regimen of zidovudine (ZDV) in preventing perinatal HIV transmission was investigated in a randomized case-placebo study conducted at two teaching hospitals in Bangkok Thailand in 1996-97. The 198 women in the intervention group were given 300 mg of ZDV orally twice a day from 38 weeks of gestation until the onset of labor and 300 mg every 3 hours thereafter until delivery. Another 199 women received a placebo. Infants in both groups were fed formula rather than breast milk. At 6 months of age 52 children (17 from the ZDV group and 35 in the placebo group) were HIV-positive; all HIV infections were evident at 2 months of age. The HIV transmission risk was 9.2% (95% CI 5.0-13.5%) in the ZDV group and 18.6% in the placebo group (95% CI 13.0-24.0%) signifying a 51% decrease in risk. The ZDV regimen used in this study is more feasible for implementation in developing country settings than the one currently used in the US (associated with a 66% reduction in HIV transmission): it costs US$50 starts later in pregnancy involves less frequent dosing and oral dosing during labor and does not involve infant treatment. On the basis of these findings ministries of health and donor agencies are urged to develop strategies to increase access to prenatal HIV testing and ZDV treatment for HIV-infected pregnant women in resource-poor settings. Further evaluation is needed of the effect of breast feeding on the efficacy of this regimen.