Congenital heart disease is an important cause of maternal morbidity and mortality during pregnancy. Pregnancy alters the circulatory and respiratory physiology with attendant deleterious effect on the mother with congenital heart disease and the foetus. Additional insult to the circulatory physiology by other factors coexisting together with congenital heart disease canfurther reduce the cardiac reserve in pregnancy and precipitate heart failure. These factors include anaemia, thromboembolism, hypertension, multiple pregnancy, strenuous physical activity, extremes of temperature and the normal physiological edema of pregnancy. Patent ductus arteriosus (PDA) can present for the first time in pregnancy. Moderate to large PDA result in significant volume overload, left ventricular dilation and dysfunction. In the woman with a hemodynamically important PDA, pregnancy may precipitate or worsen heart failure. We report a successful pregnancy in a 26 year old primigravida with previously undetected patent ductus arteriosus with preeclampsia who presented in heart failure. This case highlights the importance of intensive careful examination of pregnant patients to identify such conditions.