Hepatitis B virus (HBV) is a major cause of liver disease, cancer, and death worldwide. In the United States alone, there are up to 1.4 million people infected with HBV. Worldwide, more than 240 million people have HBV. One of the key moments across the lifespan when HBV infection becomes especially important is during pregnancy, when the developing fetus is at risk of contracting HBV. An estimated 25,000 infants are at risk of contracting HBV in the uterus or at birth, with a little less than 1% of pregnancies in the United States affected by HBV infection of the mother.
In the January 2016 Gray Journal, the Society for Maternal-Fetal Medicine (the high risk obstetrics experts, called SMFM), led by Dr. Jodie Dionne-Odom, published a review of the latest research and knowledge on HBV and pregnancy, along with an excellent run-down of recommendations and best practices.
HBV contracted at any point is scary. It can cause liver scarring (cirrhosis), liver failure, and liver cancer. In fact, chronic HBV infection causes half of all liver cancers worldwide. For newborns, the risks of transmission at birth are even higher. Transmission from mother to child during pregnancy and childbirth is responsible for about half of all chronic HBV infections worldwide. When contracted at birth, HBV is more likely to become a chronic infection and more likely to lead to worse long term liver disease. If the average adult is exposed to HBV, he has a 5-10% chance of developing chronic HBV. However, if a neonate is exposed to HBV, he has a 90% chance of developing chronic HBV if he does not receive the appropriate medications and vaccines. Worldwide, 50% of HBV infection is transmitted at birth.
Our front line defense against HBV transmission to newborns is universal screening of all pregnant women. Currently, 95% of pregnant women receive HBV screening. SMFM and ACOG (the big obstetrics and gynecology organization) recommend screening all pregnant women. If screening results are positive, then further testing can be completed to determine if the woman has acute or chronic HBV.
So what happens if a mother screens positive and has chronic HBV? Does she need a c-section? No. This report reiterates- current opinion does not support altering obstetrics practices. The current data on elective c-section to avoid transmission is conflicting and thus does not lead to a recommendation to perform a major surgery for no known benefit.
What can be done to reduce the risk of transmission? First and foremost is treatment of the newborn with HBV vaccine and the HBV immunoglobulin (the immune system fighter cells trained to attack HBV) within 12 hours after birth. 85-95% of babies who receive the HBV vaccine and HBV immunoglobulin within 12 hours of birth develop long term immunity instead of chronic disease.
Yet another recommended approach to decrease risk of transmission is control of high viral loads in the third trimester. Women with chronic HBV should have “HBV viral load testing” completed in the third trimester to tell how many copies of the virus are circulating in their blood. If the viral load is high enough, then the doctor can prescribe an antiviral medicine like tenofovir to help decrease the viral load and reduce risk of transmission.
Once baby is home, mother can breastfeed, as long as the infant received the recommended treatments. In studies comparing breastfeeding and formula-feeding, the rate of transmission was low and the same in both groups, 0-5%. Because we know there are innumerable benefits to breastfeeding, the risk-benefit analysis obviously favors breastfeeding. Finally, it’s important for mothers to remember to complete the HBV vaccine series, which is a total of three shots. To learn more about HBV and pregnancy, the article, Consult Series #38, is found here.