Risk of human immunodeficiency virus type 1 transmission through breastfeeding.

Detection of human immunodeficiency virus type 1 (HIV-1) in breast milk by culture and polymerase chain reaction does not necessarily mean that breastfeeding is a route of transmission, although evidence from several case-reports points in that direction. We undertook a systematic review of published studies meeting criteria that allowed determination of quantitative risk of transmission via breastfeeding. Based on four studies in which mothers acquired HIV-1 postnatally, the estimated risk of transmission is 29% (95% Cl 16-42%). Analysis of five studies showed that when the mother was infected prenatally, the additional risk of transmission through breastfeeding, over and above transmission in utero or during delivery, is 14% (95% Cl 7-22%). Where there are safe alternatives to breastfeeding, universal named testing of pregnant women would provide an opportunity to advise more infected women not to breastfeed and might thereby reduce the number of vertically infected children. Since breastfeeding protects against infant deaths from infectious diseases, breastfeeding is still recommended where infectious diseases are a common cause of death in childhood, despite the additional risk of HIV transmission.