Hepatitis B virus (HBV) infection in a pregnant woman poses a serious risk to her infant at birth. Without postexposure immunoprophylaxis, approximately 40% of infants born to HBV-infected mothers in the United States will develop chronic HBV infection, approximately one-fourth of whom will eventually die from chronic liver disease.
Perinatal HBV transmission can be prevented by identifying HBV-infected (i.e., hepatitis B surface antigen [HBsAg]-positive) pregnant women and providing hepatitis B immune globulin and hepatitis B vaccine to their infants within 12 hours of birth.
HBV is a 42-nm double-stranded enveloped virus of the Hepadnaviridae family. It is composed of a nucleocapsid core (HBcAg) and a viral envelope containing HBsAg. Eight HBV genotypes (A–H) and 2 provisional genotypes (I, J) have varying regional prevalence and possible differences in disease severity HBV is transmitted by percutaneous and mucosal inoculation in blood and body fluids. The virus remains viable on environmental surfaces for at least 7 days
A reactive (positive) HBsAg test indicates acute or chronic infection; HBsAg is the marker used to screen for HBV infection in pregnant women and to estimate chronic HBV prevalence. HBeAg typically correlates with higher levels of HBV DNA (viral load) and active replicationTotal antibody (immunoglobulin [Ig]G and IgM) to HepB core (anti-HBc) indicates previous or ongoing infection; IgG anti-HBc persists for life. Antibody to HBsAg (anti-HBs) indicates immunity after either infection or vaccination.