Mother-to-Infant Transmission of Hepatitis C Virus. Results
Analysis of virological parametersFor the evaluation of possible risk factors for the vertical transmission of HCV, 73 pregnant, HCV-infected women were identified between 1994 and 1999. Serum samples of 71 women (97%) were tested by RT-PCR; 58 women (82%) were HCV RNA positive. Four mothers had been HCV RNA positive before pregnancy but were negative during pregnancy. For 11 mothers, HCV infection was confirmed by the identification of HCV-specific antibodies by use of an immunoblot.
The 73 women gave birth to 75 children, including 2 sets of twins; 9 of the children were HCV infected. Seven (10%) mothers were HIV-HCV–coinfected, 59 (81%) were HIV seronegative, and, for 7 (10%), HIV status could not be determined. For 6 of the 7 HIV-HCV–coinfected mothers, HCV- and HIV-PCRs were done, and both HCV RNA and HIV DNA were detected. Of the 7 mothers with HIV coinfection, 1 transmitted HCV to her offspring and 1 transmitted HIV, but none transmitted both viruses to her child. One of these 7 children (the HIV-infected one) was delivered vaginally, 5 (including the HCV-infected child) were delivered by elective cesarean section, and the mode of delivery was unknown for 1 child.
Analysis of risk factors for mother-to-infant transmission of HCVEstimation of the likelihood of mother-to-infant transmission of HCV for individual virological and clinical parameters was done by unconditional logistic regression analysis. The sample size varied, depending on the number of women for whom data were available for a particular variable Detectable HCV viremia in the mother was a prerequisite for transmission, since only children from mothers with detectable viral RNA became HCV infected. The mothers of infected children had a higher mean HCV load than did mothers of uninfected children (7.3×105 vs. 2.5×104 copies/mL), and this difference in HCV load was even more pronounced among mothers who underwent vaginal delivery (8.1×105 vs. 1.4×104 copies/mL). However, no statistically significant association could be found between maternal HCV RNA level and the risk of mother-to-infant transmission of HCV, although a trend toward a higher risk of transmission with increasing levels of maternal viremia was noted.
In mothers with HIV-HCV coinfection, no increased risk for mother-to-infant transmission of HCV was observed in the present study, although the number investigated was small. In the 7 HIV-HCV–coinfected mothers for whom a quantitative HCV-PCR result was available, the mean HCV load was not significantly higher than that in mothers without HIV-HCV coinfection (1.7×105 vs. 3.2×104 HCV RNA copies/mL; n = 53; P=.113, Mann-Whitney U test).