[Incidence of HBsAG in symptom-free pregnant women. Results of screening at the University of Zurich Gynecology Clinic].

Passive and active immunization prevent materno-fetal and postnatal hepatitis B-virus infection. Precondition for interruption of perinatal transmission is knowledge of the mothers' hepatitis B markers before delivery. In switzerland the prevalence of chronic asymptomatic pregnant HBsAG carriers is not known. From February to December 1983 all pregnant women at the Obstetric Clinic, University Hospital of Zurich were screened for HBsAG. 30 out of 2550 women were HBsAG positive (1.2%); the prevalence among Swiss women is 0.5%, and among immigrants 1.9%. It is suggested that screening for HBsAG be confined to pregnant women who belong to a risk group and to immigrants, and that all children born of HBsAG positive mothers be immunized actively and passively regardless of the presence of HBeAG and/or anti-HBe.