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

This prospective study, designed to demonstrate the rate of vertical transmission of hepatitis C virus (HCV), enrolled 170 consecutive anti-HCV antibody-positive women and their 188 infants over a 12-month period. HCV screening used second- and third-generation enzyme-linked immunosorbent assays. HCV-RNA was quantified in the women using the polymerase chain reaction technique. The infants were followed up until either no HCV antibody remained or HCV infection was diagnosed. The HCV-positive women had a mean age of 31 years at the time of delivery, not significantly different from HCV-negative women delivering in the same period. A history of intravenous drug use was obtained from 46.5% of the antibody-positive women. Dental care and surgery, transfusions, and sexual intercourse with an antibody-positive partner also were risk factors. Three women were positive for hepatitis B surface antigen at delivery, and four seroconverted after vaccination. HIV-1 was documented in approximately one fifth of the anti-HCV-positive group. The caesarean section rate was not higher in antibody-positive women. Vertical transmission of HCV was documented in five cases, 2.7% of the total. Two of these five mothers were also HIV-positive, for a transmission rate of 5.4% in this group. All five affected infants were born to women who were positive for HCV-RNA but who had no severe liver disease. The transmission rate for infants delivered by caesarean section was 4.1%. All infants possessed anti-HCV antibody at birth but only 14 remained positive after 12 months. Antibody continued to disappear in these infants and, at 18 months, only five remained antibody-positive. Mothers who transmitted HCV infection had significantly higher levels of viremia, reflected in HCV-RNA titers, than did the others. Vertical transmission of HCV infection from mother to infant was quite infrequent in this prospective study, although it remains necessary to warn HCV-infected women who become pregnant of the risk that their child could be affected. Although early diagnosis of infection probably will not alter management, a negative finding could relieve the mother’s anxiety.