Should all pregnant women be screened for hepatitis B?

To assess the sensitivity of historical risk factors for identification for hepatitis B surface antigen (HBsAg)-positive parturients, 4399 pregnant women were consecutively screened for HBsAg. Information regarding risk for hepatitis B infection was obtained from each HBsAg-positive parturient. Twenty-three HBsAg-positive subjects were identified (5.2/1000 deliveries). The HBsAg carrier rate (18/2231, or 8.1/1000 deliveries) was significantly higher in women of black, Asian, or Hispanic origin than in the remaining ethnic groups (non-Hispanic whites plus all others, 5/2168, or 2.3/1000 deliveries) (chi square, 5.95; p = 0.016). Risk factors for identification of HBsAg-positive women were present in 10 of 22 asymptomatic subjects (sensitivity, 45%; 95% confidence interval, 24% to 68%). Much of the information required to assess one of these risk factors, previous infection, involved detailed questioning and is unlikely to be obtained in the context of conventional obstetrical care. Routine maternal HBsAg screening programs may be needed if transmission of hepatitis B from mother to infant is to be prevented.