Maternal Levels of Plasma Human Immunodeficiency Virus Type 1 RNA and the Risk of Perinatal Transmission

Little was known of the biology of perinatal transmission of human immunodeficiency virus type 1 (HIV-1) when zidovudine treatment was proposed and subsequently proved effective for reducing the risk of neonatal infection. 1 Clarification of the relative contribution of maternal plasma HIV-1 RNA levels and other factors known to influence the risk of transmission might provide insight into the timing of transmission of the virus to the infant. We undertook this study to determine the relation between maternal plasma HIV-1 RNA levels and the risk and timing of perinatal transmission of HIV-1 infection, using data from one of the largest prospectively . . .