Increased vertical transmission of human immunodeficiency virus from hepatitis C virus-coinfected mothers. Women and Infants Transmission Study.

To determine if hepatitis C virus (HCV) infection affects vertical transmission of human immunodeficiency virus (HIV), 487 HIV-infected pregnant women in the prospective, multicenter, Women and Infants Transmission Study had HCV antibody (anti-HCV by second-generation ELISA) and HCV RNA (by quantitative polymerase chain reaction) measured in peripartum maternal plasma; 161 (33%) were anti-HCV-positive. HIV vertical transmission occurred from 42 HCV-infected mothers (26.1%) versus 53 HCV-uninfected mothers (16.3%; odds radio [OR], 1.82; P = .01). In a logistic regression model that included maternal drug use, a potential confounder, HCV infection was marginally associated with perinatal HIV transmission (OR, 1.64; P = .05), whereas drug use was not. Women who transmitted HIV had higher levels of HCV RNA (median, 721,254 copies/mL) than those who did not (337,561 copies/mL; P = .01). Maternal HCV infection is associated with increased HIV vertical transmission. Further studies are needed to ascertain if HCV directly affects perinatal HIV transmission or is a marker for another factor, such as maternal drug use.