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In pregnant women, hepatitis B virus (HBV) infection presents the risk of mother-to-child (vertical) transmission. The contaminated newborn most often remains a chronic carrier. Mother-to-child transmission can be avoided by serovaccination of the newborn. Screening for HBs antigen is essential in all pregnant women; in France, it is mandatory at the 6-month prenatal examination. All infants born to mothers who are carriers of HBs antigen must receive a serovaccination against this virus, by intramuscular injection of vaccine and of hepatitis B immune globulin (H-BIG, 100 or 200 IU), in two different sites, in the first hours after birth. Vaccination then continues, according to the recommended protocol. Although the combination of vaccination and H-BIG is very effective in preventing chronic carriage in children (efficacy >90 %), some children may nonetheless be contaminated, especially when the viral load is very high during pregnancy. These women with very high viral loads may receive lamivudine treatment at the end of pregnancy to diminish viral load and thus the risk of chronic carriage in the child; however the role of this drug in this situation is not yet clearly defined. The efficacy of the serovaccination must be confirmed in all children by a serologic examination (HBs antigen and anti-HBs antibodies) at some time after the last vaccination. Children carrying the HBs antigen must be seen by a pediatrician who has experience with viral hepatitis. When HBs antigen is found in a woman during pregnancy, a specialist should be consulted and the family should undergo complete serologic testing (HBs antigen, anti-HBc and anti-HBs antibodies). |
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