July 2003

VIENNA, Austria — Children delivered vaginally and whose mothers sustained a perineal or vaginal laceration had a six-fold higher risk of hepatitis C virus (Hepatitis C Virus) than vaginally delivered children whose mothers had no laceration, according to a retrospective study of 73 Hepatitis C Virus-positive pregnant women who gave birth to 75 children.

“In our study, vaginal delivery itself did not increase the risk for transmission, compared with cesarean section,” said Heidemarie Holzmann, MD, an associate professor of virology here at the Institute of Virology, University of Vienna. “But we were surprised to find a correlation between vaginal lacerations and transmission of Hepatitis C Virus. We suspect these children had a longer exposure to blood because the duration of the birth was slightly longer.”

In the study, 82% of Hepatitis C Virus-positive mothers were Hepatitis C Virus-RNA positive during pregnancy, and 10% were coinfected with HIV. Nine children had Hepatitis C Virus, one had HIV, but no child was HIV-Hepatitis C Virus coinfected. “Except for one HIV-Hepatitis C Virus coinfected woman, none of the 23 mothers who had a cesarean section transmitted Hepatitis C Virus to her offspring,” she said.

Among vaginal deliveries, the mean Hepatitis C Virus load of mothers who transmitted Hepatitis C Virus to their infants was higher than those who did not (8.1 × 105 vs. 1.4 × 104 copies/ml; P=.056). Furthermore, a reduction in umbilical cord blood pH (relative risk, 3.9; P=.04) or the occurrence of perineal or vaginal laceration (relative risk, 6.4; P=.028) during vaginal delivery significantly increased the risk of vertical Hepatitis C Virus transmission.

The study, which recently appeared in the Journal of Infectious Disease, stated that it would be premature to recommend routine cesarean section for Hepatitis C Virus-positive women. However, “elective cesarean section may reduce the risk of vertical transmission of Hepatitis C Virus among mothers with high Hepatitis C Virus viremia,” Holzmann said.

To date, only a few risk factors influencing vertical Hepatitis C Virus transmission have been identified. These are HIV coinfection and the presence of Hepatitis C Virus RNA in maternal blood. “It is still controversial whether high maternal virus load also poses a higher risk for transmission,” Holzmann said. Moreover, “the timing of perinatal transmission is uncertain, and understanding of the obstetrical factors that influence vertical transmission of Hepatitis C Virus is still limited.”

“High viremia was not a statistically significant risk factor for transmission, nor was vaginal delivery itself,” she said. “But we found that perinatal infantile hypoxia and vaginal or perineal laceration that occurred during vaginal delivery significantly increased the risk for Hepatitis C Virus transmission,” she said

Clinical data on Hepatitis C Virus-positive mothers were assessed by questionnaires sent to mothers and their gynecologists following delivery and by review of case histories and obstetric notes. “Hepatitis C Virus was reported to have been acquired through injecting drug use in 41 of women (56%) and from infected blood or blood products in six (8%),” Holzmann said. Other or unknown routes of acquisition were reported in 26 (36%) of the women.

Of the seven mothers who were HIV-coinfected, one transmitted Hepatitis C Virus to her offspring and one transmitted HIV, but none transmitted both viruses to her child. The HIV-positive child was delivered vaginally, whereas five children (including the Hepatitis C Virus-positive one) were delivered by elective cesarean section. For the remaining child, the mode of delivery was unknown.

The mothers of positive Hepatitis C Virus children had a higher mean Hepatitis C Virus load compared with mothers of uninfected children (7.3 × 105 vs. 2.5 × 104 copies/ml). “But no statistically significant association could be found between maternal Hepatitis C Virus-RNA level and the risk of mother-to-infant transmission of Hepatitis C Virus. However, there was a trend toward a higher risk of transmission with increasing levels of maternal viremia,” Holzmann said.

In mothers with HIV-Hepatitis C Virus coinfection, no increased risk for mother-to-infant transmission of Hepatitis C Virus was observed, although the number investigated was small.

Two other factors that had no apparent impact on transmission rates were birth weight of the newborn and gestational age. On the other hand, every reduction in umbilical cord blood pH by 0.1 increased the risk of mother-to-infant transmission of Hepatitis C Virus by four-fold (assuming a pH standard value of 7.27).

For more information:

·         Steininger C, Kundi M, Jatzko G, et al. Increased risk of mother-to-infant transmission of hepatitis C virus by intrapartum infantile exposure to maternal blood. J Infect Dis. 2003:187:345-351.