Prospective study of mother-to-infant transmission of hepatitis C virus

Background Mother-to-infant transmission of hepatitis C virus (HCV) could b ecome the main route of HCV infection in the future because there are no me thods available to prevent vertical infection. The aim of this study was to determine the incidence of mother-to-infant transmission in infants born t o mothers who tested positive for anti-HCV antibodies and to elucidate asso ciated risk factors for transmission. Methods. Screening was conducted for 16 800 pregnant women with an anti-HCV antibodies test, and 154 mothers were positive. From the positive group 14 1 mothers were enrolled in the study and their 147 infants mere followed fr om birth for serum alanine aminotransferase activity, anti-HCV antibodies a nd HCV RNA. HIV infection was tested in 73 of 141 mothers, all of whom were negative. Results. Thirty-three infants were dropped from the study because they were followed for <6 months or were not tested adequately. Of the 114 infants f inally evaluated 9 (7.8%) had detectable HCV RNA. The transmission rate was not influenced by the mode of delivery [vaginal delivery, 8 of 90 cs. cesa rean section, 1 of 24 (P = 0.396)] or by the type of feeding [9 of 98 for b reast-fed infants vs. 0 of 16 for formula-fed infants (P = 0.243)]. All inf ected infants were born to mothers who had HCV viremia at the delivery (P = 0.040) and to those with a high viral load (P = 0.019). Conclusions. Our prospective study showed that the transmission rate of mot her-to-infant HCV infection was 7.8% in anti-HCV antibody-positive mothers. Risk was related to the presence of maternal HCV viremia at delivery and a high viral load in the mothers.