Perinatal transmission of hepatitis B virus.

Transmission of hepatitis B virus from carrier mothers to their infants seems most likely to occur during birth. Both cord blood and breast milk have been found to be positive (in 35% and 72% of cases respectively) for hepatitis B surface antigen (HBsAg), but they do not appear to play an important role in transmission. To control this problem high-risk women should be tested during pregnancy for HBsAg. The infants of infected women should be given several doses of hepatitis B immunoglobulin starting at birth. In less developed regions, where hepatitis B is endemic, administration of the immunoglobulin in combination with vaccine, or even the vaccine alone, may be preferable in order to provide infants with lasting protection.