Grossesse et hépatite B en Picardie : traçabililité du dépistage et prévalence

[Hepatitis B and pregnancy. Part 1. Thirteen practical issues in antenatal period]

In France, the prevalence of chronic hepatitis B is about 1% in pregnant women (usually asymptomatic carriers of HBsAg). The risk of maternal-fetal transmission of hepatitis B is particularly high when viral load measured by PCR is higher in mothers (above 7 log) or HBeAg is present. In case of maternal-fetal transmission of hepatitis B, the risk to the newborn of developing subsequent chronic hepatitis B is very high (90%), with long-term complications such as cirrhosis and hepatocellular carcinoma. The prevention of maternal-fetal transmission is based on systematic testing for hepatitis B during pregnancy, followed by serovaccination of the newborn at birth. If necessary, amniocentesis can be realised but will avoid the realization of a transplacental gesture. In case of high viral load, the establishment of a maternal antiviral treatment with lamivudine or tenofovir from 28SA can further reduce the risk of transmission. Given the low resistance it induces, tenofovir should be used preferentially.

[Pregnancy and viral hepatitis B and C]

The screening for HBsAg is a medical obligation in France during pregnancy. A serovaccination with antiHBs immunoglobulins (100 IU) and a 1st dose of vaccine (10 μg) has to be realized during the first 12 hours of life when the mother is HBsAg+. The serovaccination failures are related to high maternal viral load (HBV-DNA>7 log IU/mL). In this case, a treatment with analogue (tenofovir) associated with serovaccination could be performed during the last trimester of pregnancy. The risk of mother-to-child transmission of virus C is around 3 to 5% in case of HCV-RNA positive without co-infection with HIV. The mode of delivery is unchanged in case of maternal HBV or HCV. Breast-feeding is not contra-indicated in case of maternal HBV or HCV infection.

[Prophylaxis of mother-to-infant transmission of hepatitis B virus]

Hepatitis B virus (HBV) infection is a worldwide health problem and mother-to-infant (or vertical) transmission is the main source of chronic infection in Asian countries. Administration of HBV vaccine to the infant at birth, with or without concurrent specific immunoglobulin, efficiently prevents such transmission (efficacy>90%). In France, testing Ag HBs is mandatory during pregnancy in all pregnant women. Infants born to Ag HBs-positive mothers should receive the first injection of vaccine and one injection of specific immunoglobulins at birth. Vaccination should thereafter be completed according to a three-injection protocol (at 1 and 6 months) or a four-injection protocol in case of prematurity. Failure of immunoprophylaxis can be observed when the viral load is very high in the mother during pregnancy (HBV-DNA levels>200,000 IU/mL). In such women, antiviral therapy with analogs (lamivudine, telbivudine, or tenofovir) during the third trimester of pregnancy and 1 month post-partum, in association with accurate immunoprophylaxis, may prevent vertical transmission. The optimal cut-off value of maternal viral load for antiviral therapy in late pregnancy and post-partum to prevent vertical transmission is still under debate.