During pregnancy cardiac output rises by 40-50%. At first stroke volume in particular increases, with the heart rate rising mainly in the second part of the pregnancy. More and more women with congenital heart disease are reaching adulthood and want to become pregnant. The haemodynamic changes during pregnancy are an additional burden for women with heart disease. Risk factors for occurrence of important cardiac problems during pregnancy are: previous cardiac events, lower functional class, cyanosis, left-sided heart obstruction or a diminished systolic function of the systemic ventricle. Pregnancy is contraindicated in pulmonary hypertension, in Marfan syndrome with an ascending aorta diameter of > 50 mm and in severe mitral or aortic valve stenosis. The recurrence risk for children varies between 3 and 50%, depending on the nature of the congenital heart disease. Foetal outcome is depending on the haemodynamic situation and medication use of the mother. ACE inhibitors are contraindicated during pregnancy.