Objective: In this study we evaluated cardiovascular changes during pregnancy. Our main aim was, in cardiovascular disease, pregnancy causing worse heart problems and increase functional classes during gestation. In which groups of patients, before pregnancy, is therapeutic management like intervention or surgery necessary to be performed, and fetal and newborn complications, evaluated.Methods and Materials: In this prospective study we evaluated, 53 pregnant women with heart disease who were admitted to Dept of Cardiology, Imam Reza Hospital before or immediately after delivery. Maternal gestational age, parity, the kind of heart disease history of cardiac surgery, and also Abortion, stillbirth, and functional classes based on New York Heart Association classification were done.After collection of information, percent of the data was assessed and presented.Results: At the time of admission (47.1%) of patients were in functional class II, class I (33.9%) class III. (13.2%), class IV (5.6%). In this study the most common cause of cardiovascular disease (Figure III) was rheumatic heart disease (69.8%) and the most common cause of patients admission to hospital (Figure I) was those, with the history of heart disease (81.1%), and most common clinical manifestation (Figure II) was exertional dyspnea (35.8%) .Conclusion: Patients with MR, mild MS, AI & mild AS, VSD and functional class I & II can tolerate pregnancy and delivery well. But usually for pts in class III, IV, they will have serious problems during pregnancy and delivery. The decision of continuation or termination of pregnancy in high risk pts for example severe MS, AS and pulmonary hypertension, izenmenger's syndrome, high functional class are depending on the consultation between cardiologist, cardiac surgeon, obstetrician and pts family.