Update on perinatal HIV transmission.

Over the past decade, much progress has been made in understanding the risk factors and timing of perinatal HIV transmission. Even more impressive have been the successful clinical trials with antiretrovirals, such as ZDV, ZDV-3TC, and nevirapine, that demonstrated significant reductions in the risk for infant infection. Within the United States and Europe, these trial results have led to rapid implementation and dramatic decreases in new perinatal HIV cases since 1994. An immediate challenge is to rapidly translate the short-course antiretroviral trial results with ZDV and nevirapine into public health policy and practice in resource-poor settings, where almost 600,000 neonates continue to become infected by mother-infant HIV transmission each year. Physicians must also test strategies to further decrease the risk for infant HIV infection during the breast-feeding period.