Abstract

Transplacental transmission of hepatitis B virus from hepatitis B antigen carrier mothers was investigated by studying the presence of the antigen and its antibody in maternal blood, umbilical cord blood, and amniotic fluid. Hepatitis B antigen was shown in the umbilical cord blood of 2 out of 14 newborns whose mothers were permanent hepatitis B antigen carriers. The antigen was eliminated from the blood of these newborns in less than 3 months. It was also detected in the concentrated amniotic fluid of one hepatitis B antigen cord blood-positive case. Antibodies (anti-HBs) crossed the placental barrier easily and were found in the umbilical cord blood and in the amniotic fluid. They were not detected in the umbilical cord blood and amniotic fluid of any of the studied newborns of hepatitis B antigen carrier mothers.

These data indicate that the fetuses of carrier mothers are exposed to the hepatitis B virus. However, chronic antigen positivity and anti-HBs production was not shown. Occurrence of in utero infection and subsequent resolution cannot be excluded, but it appears more probable that in utero infection is blocked.