Objective: To determine the risk factors for and timing of vertical transmission of hepatitis C virus in women who are not infected with HIV-1.
Design: Follow up for a median of 28 (range 24-38) months of babies born to women with antibodies to hepatitis C virus but not HIV-1.
Subjects: 442 mothers and babies, of whom 403 completed the study.
Main outcome measures: Presence of antibodies to hepatitis C virus and viral RNA and alanine aminotransferase activity in babies. Presence of viral RNA, method of infection with hepatitis C, method of delivery, and type of infant feeding in mothers.
Results: 13 of the 403 children had acquired hepatitis C virus infection at the end of follow up. All these children were born to women positive for hepatitis C virus RNA; none of the 128 RNA negative mothers passed on the infection (difference 5%, 95% confidence interval 2% to 7%). 6 children had viral RNA immediately after birth. 111 women had used intravenous drugs and 20 had received blood transfusions. 11 of the infected children were born to these women compared with 2 to the 144 with no known risk factor (difference 7%, 2% to 12%).
Conclusions: This study suggests that in women not infected with HIV only those with hepatitis C virus RNA are at risk of infecting their babies. Transmission does seem to occur in utero, and the rate of transmission is higher in women who have had blood transfusions or used intravenous drugs than in women with no known risk factor for infection.
- Little information exists on vertical transmission of hepatitis C virus in women not infected with HIV
- This study in a large unselected population of infants born to HIV-1 negative mothers suggests that intravenous drug use itself is an important risk factor for transmission of hepatitis C virus
- Maternal post-transfusional hepatitis is also an important risk factor for infection of infants
- Viral genotype, maternal viraemia, type of delivery (vaginal delivery or caesarean section) and breast feeding do not seem to be risk factors
- In utero transmission of hepatitis C virus has been suggested by RNA positivity on day of birth in some infected children