The autors estimate the prevalence of Hepatitis B Surface Antigen in an obstetric population, admitted to the out-patient clinic of M.J.D. during one year. A questionnaire was designed to identify the possible risk factors associated whith the presence of HB surface antigen. Among 1333 pregnant women, 1258 were screened, and 627 concluded the study: screening and questionnaire. In the overall sample, the preval...