Hepatitis B infection in a large municipal obstetrical population: characterization and prevention of perinatal transmission.

We have previously described a large municipal obstetrical population in which the carriage rate of hepatitis B (HBV) is 1.2%. The present study was undertaken to determine the effectiveness of our immunoprophylaxis regimen (hepatitis B immune globulin at 36-72 h, hepatitis B vaccine at 36-72 h, 1 month and 6 months) in eliciting protective antibody to hepatitis B surface antigen (anti-HBs) in the infants of these women, the rate of perinatal transmission of HBV in this population prior to vaccination, the prevalence of anti-hepatitis delta antibody (anti-HD), and the prevalence of liver disease in our hepatitis B surface antigen-positive (HBsAg+) population. Four hundred eleven infants of HBsAg+ women were born during the 33-month study period. Of these, only 64 (15.6%) completed the vaccine series and returned for testing at 12 months. Sixty of the 64 had anti-HBs, and one (1.6%) had become HBsAg+. Eighty-nine older siblings of the immunized infants were tested, and 17 (19%) were HBsAg+. Of 54 mothers and eight siblings who were HBsAg+, none had anti-HD. Serum alanine aminotransferase (ALT) levels were normal in 53 of 54 HBsAg+ mothers tested. These data demonstrate 1) reduction of perinatal transmission of HBV from 19% to 1.6% using our protocol, 2) absence of hepatitis delta infection in this population, and 3) high prevalence of asymptomatic carriage of HBV, rather than clinically significant liver disease, in this population. It is imperative to improve compliance in order to maximize the effectiveness of immunoprophylaxis for newborns of HBsAg+ mothers.