Background: Maternal and neonatal complication rates are increased in pregnant women with heart disease. Cardiac risk assessment may be improved by defining low and high-risk groups. Aims: To analyze pregnancy risks in low and high-risk women with cardiovascular diseases. Methods and results: Pregnancy outcomes were analyzed in 93 consecutive women with heart disease, monitored in a single-centre cohort between 1996 and 2006. Women were classified according to pre-defined risk predictors as high-risk (left ventricular [LV] ejection fraction b 50%, NYHA class N II or cyanosis, peak LVoutflow gradient N 60 mmHg) or low-risk (not meeting these criteria). Mean age was 28.1± 5.7 years. 81.7% presented with congenital, 10.8% with acquired heart disease, and 7.5% with myocardial diseases. Severe maternal complications developed in 12.9% of all women: 6.5% heart failure, 3.2% arrhythmias, and 2.2% thrombotic complications. Maternal mortality was 1.1%. Women at high-risk (24.7%) had a 6.1-fold higher maternal complication rate and a 6.1 times higher foetal/neonatal event rate (abortion and stillbirth). 64.7% of the high-risk women delivered prematurely, before the 37th week, compared to 16.4% in the low-risk group. Conclusions: Despite pronounced clinical variability of congenital and acquired heart diseases, a small number of risk conditions can effectively characterize women in whom pregnancy is associated with appreciably increased maternal and foetal risk.