Background Pregnant women with heart disease are at high risk.Studies of risk factors of these patients are of great significance to improve maternal and fetal outcomes.In this paper,we try to discuss the main risk factors of cardiac events in pregnant women with heart disease and to establish a risk assessment system.Methods A retrospective analysis was carried out for pregnancies in 1741 women with heart disease who delivered in Shanghai Obstetrical Cardiology Intensive Care Center between January 1993 and September 2010.A Logistic regression model was used to identify independent risk factors of cardiac events and calculate the risk index in pregnant women with heart disease.Results The composition of heart disease in pregnant women was arrhythmia (n=662,38.00％),congenital heart disease (CHD; n=529,30.40％),cardiomyopathy (n=327,18.80％),rheumatic heart disease (RHD; n=151,8.70％),and cardiopathy induced by pre-eclampsia (n=53,3.00％).Main cardiac events were heart failure (n=110,6.32％),symptomatic arrhythmia needing medication (n=43,2.47％),cardiac arrest (n=2,0.11％),syncope (n=3,0.17％),and maternal death (n=10,0.57％).Six independent risk factors to predict cardiac events in pregnant women with heart disease were cardiac events before pregnancy (heart failure,severe arrhythmia,cardiac shock,etc.,P=0.000),New York Heart Association (NYHA) class ＞ll (P=0.000),oxygen saturation ＜90％ (P=0.018),pulmonary artery hypertention (PAH)＞50 mmHg (P=0.025),cyanotic heart disease without surgical correction (P=0.015),and reduced left ventricular systolic function (ejection fraction ＜40％,P=0.003).Every risk factor was calculated as 1 score.The incidence of cardiac events in patients with scores 0,1,2,3,and ≥4 was 2.10％,31.61％,61.25％,68.97％,and 100.00％ respectively.Conclusions Pregnancy with heart disease could lead to undesirable pregnancy outcomes.The risk of cardiac events in pregnant women with heart disease could be assessed by risk index.