Objectives: To describe the echocardiographic features, underlying causes, and outcome of fetuses with dilated cardiomyopathy.

Design: A retrospective observational study between 1983 and 2003 at a tertiary centre for fetal cardiology.

Patients: Affected fetuses were identified using a computerised database. We included fetuses with dilation and reduced systolic function of either the right ventricle, left ventricle, or both. We excluded fetuses with abnormal cardiac connections, arrhythmias, or stenosis of the aortic or pulmonary valves. In all, we identified 50 fetuses, born to 46 mothers. Of the fetuses, 24 had biventricular cardiomyopathy, 17 had isolated right ventricular cardiomyopathy, and 9 had isolated left ventricular cardiomyopathy. Two-thirds of the fetuses (32) were hydropic at some point during gestation.

Main outcomes: A cause of cardiomyopathy was identified in 37 cases (74 per cent). This was genetic or metabolic in 11 fetuses; infective in 11; fetal anaemia, without proven parvovirus infection, in 5; of cardiac origin in 5; and an association with renal disease in 5. In 10 cases (20 per cent), the pregnancy was terminated. Based on an intention to treat, the survival to delivery was 25 of 40 (62.5 per cent, 95 per cent confidence intervals from 46 to 77 per cent), at 28 days was 17 of 40 (42.5 per cent, 95 per cent confidence intervals from 27 to 59 per cent), and at 1 year was 15 of 40 (37.5 per cent, 95 per cent confidence intervals from 23 to 54 per cent). The overall survival of non-hydropic fetuses was 9 of 18 (50 per cent), compared to 6 of 32 (18 per cent) hydropic fetuses.

Conclusions: Genetic, metabolic, infective, and cardiac diseases may present with dilated cardiomyopathy during fetal life. There is a high rate of spontaneous intra-uterine and early neonatal death. The prognosis is particularly poor for hydropic fetuses.