Preventing Mother-to-Child Transmission of HBV

Pregnant women with Hepatitis B virus (HBV) infection are less likely to pass the virus on to babies delivered by elective cesarean section, compared to those delivered vaginally or by urgent cesarean section, according to the October issue of Clinical Gastroenterology and Hepatology. Elective cesarean sections for women with pre-delivery levels of HBV DNA ≥1,000,000 copies/mL could reduce vertical transmission.

NewbornPerinatal transmission is the most common route of HBV infection in Asian countries. Immunoprophylaxis is not effective in many infants born to women with high levels of viremia, resulting in significant numbers of newborns with the infection.

Although rates of mother-to-child transmission decrease when women receive antiviral therapy during pregnancy, little is known about the long-term safety of these drugs for the children. A survey of physicians found that 48% preferred not to provide antiviral treatment for pregnant women.

Furthermore, there are variable and unpredictable changes in HBV DNA levels during pregnancy—a mother with a low level of HBV DNA can become highly viremic during the last few weeks of pregnancy.

Calvin Q. Pan et al. investigated whether mode of delivery affected transmission. They analyzed data from 673 infants born to HBV-positive mothers through vaginal delivery, 496 born via elective cesarean section, and 240 born via urgent cesarean section. All babies were immunized against HBV, and the vaccine was assumed to have failed in infants who tested positive for hepatitis B surface antigen when they were 7–12 months old.

Pan et al. found that HBV infection was transmitted to a smaller percentage of infants born by elective cesarean section (1.4%) than by vaginal delivery (3.4%) or urgent cesarean section (4.2%). Women with HBV DNA levels <1,000,000 copies/mL did not transmit the infection to their infants, regardless of method of delivery. There were no differences in maternal or infant morbidity and mortality among the groups.

In an editorial that accompanies this article, Long H. Nguyen et al. says that given the long-term benefits of preventing mother-to-child transmission of HBV and the reassuring safety profile of elective cesarean section for mothers and babies, this procedure could complement appropriate immunoprophylaxis for mothers with chronic hepatitis B and pre-delivery viral loads greater than 1,000,000 copies/mL who do not wish to take or do not have access to anti-HBV drugs.

However, large randomized controlled trials to compare elective cesarean section and vaginal delivery are needed, with and without prophylactic anti-HBV treatment.

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About Kristine Novak, PhD, Science Editor

Dr. Kristine Novak is the science editor for Gastroenterology and Clinical Gastroenterology and Hepatology, both published by the American Gastroenterological Association. She has worked as an editor at biomedical research journals and as a science writer for more than 12 years, covering advances in gastroenterology, hepatology, cancer, immunology, biotechnology, molecular genetics, and clinical trials. She has a PhD in cell biology and an interest in all areas of medical research.
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