Evaluation of fetal bradycardia noted during a routine prenatal visit at 24 weeks' gestation in a mother without symptoms showed an antibody-mediated heart block with anti-La (SSB) antibody present. The fetus had a pericardial effusion and ascites. After maternal steroid therapy, the ascites resolved and the pericardial effusion was substantially diminished. Steroid therapy may be a helpful adjunct for treatment of a premature infant with hydrops as a result of antibody-mediated heart block.