Eisenmenger syndrome in pregnancy: a possible cause of neonatal polycythemia and persistent fetal circulation.

A 23-year-old white primigravid woman with Eisenmenger syndrome and hypoxemia was delivered of a male infant at 34 weeks' gestation after spontaneous onset of labor. The infant was small for gestational age, weighing 1670 g. He subsequently developed respiratory distress and was found to have a high hematocrit with clinical and echocardiographic evidence of persistent fetal circulation. After partial exchange transfusion with plasma, the hematocrit, pulmonary vascular resistance, and arterial oxygen tension became normal. The authors suggest that chronic maternal hypoxemia during pregnancy may cause polycythemia and increased pulmonary vascular resistance in the newborn, leading to persistent fetal circulation.