Factors Influencing Neonatal Infection by Hepatitis B Virus

Abstract

Hepatitis B infection occurred and persisted in 13 of 27 infants whose mothers had acute hepatitis in pregnancy or in the first 2months postpartum, but only one of 21 infants whose mothers were asymptomatic hepatitis B antigen carriers. If the maternal icteric illness was in the first two trimesters, however, the rate of chronic neonatal infection (one of 10) was not significantly different from that for carriers. The greater frequency of subtype ay as a cause of persistent infection in infants could be attributed to relative distribution of ay and ad strains among acutely ill mothers and carriers. Hepatitis B antigen of both subtypes crossed the placenta equally. When the mother had antigenemia at delivery, counterelectrophoresis gave only one positive result with 22 cord bloods; radioimmunoassay, however, was positive with an additional 10. The presence of hepatitis B antigen in cord blood had no necessary relation to whether the infant subsequently showed antigenemia. It appears that the developmental period when exposure occurs, rather than the clinical status of the mother or the subtype, is the most important determinant whether the infant will be chronically infected.