Prospective reevaluation of risk factors in mother-to-child transmission of hepatitis C virus: High virus load, vaginal delivery, and negative anti-NS4 antibody

Of 21,791 pregnant women screened in Tottori Prefecture, Japan, 127 (0.58%) were positive for anti-hepatitis C virus (HCV) antibody and 84 (0.39%) wer e positive for HCV RNA. Of 84 children followed up for at least 6 months, 7 (8%) were infected. All of them were born to 26 mothers with a high virus load (HVL; greater than or equal to2,5 x 10(6) RNA copies/mL [27%]), compar ed with 0 of 58 children born to non-HVL mothers (P < .001). Because all th e infected children were vaginally delivered, the infection rate among 16 v aginally delivered children born to the HVL. mothers was as high as 44%, Th e prevalence of anti-NS4 antibody in the mothers with an infectious HVL was significantly lower than that in the mothers with a noninfectious HVL (P = .048), Analysis of our results suggests that maternal HVL, vaginal deliver y, and negative anti-NS4 antibody are significant risk factors for the moth er-to-child transmission of HCV.