Prospective study of mother-to-infant transmission of hepatitis C virus: a 10-year survey (1990-2000)

Background. The purpose of this study was to determine the rate of vertical transmission of hepatitis C virus (HCV). We also aimed to analyze the time of clearance of maternal antibodies in the serum of non-infected babies. Methods. Between March 1990 and March 2000, 170 consecutive anti-HCV-positive women and their 188 babies entered this prospective study. All women were analyzed for HCV-RNA using polymerase chain reaction (PCR). The babies were followed-up until HCV-antibody clearance or until the diagnosis of HCV infection. Results. The vertical transmission rate was 2.7% overall, and it was higher in HIV co-infected women (5.4%, 2/37) than in HIV-negative women (2.0%, 3/151). All infected infants were born to mothers who had HCV viremia at delivery. The transmission rate was influenced by maternal levels of viremia. 37.2% of uninfected children became HCV-antibody negative by 6 months and 88.0% by 12 months. Babies born from HCV-RNA-positive mothers lost anti-HCV antibodies later (9.21+/-3.72 months) than babies born from HCV-RNA-negative mothers (7.47+/-3.46 months) (p<0.05, Kolmogorov-Smirnov test). Conclusions. The risk of HCV vertical transmission is very low in HCV-positive/HIV-negative women and it is restricted to infants born to HCV viremic mothers. High maternal viral load is predictive of the vertical transmission. The clearance time of antibodies in non-infected babies is significantly longer if the mother is viremic.