Abstract Objectives The purpose of this work was to study maternal and fetal outcomes of women with uncorrected congenital heart disease (CHD). Background Globally, CHD is an important cause of maternal morbidity and mortality in women reaching reproductive stage. Data are lacking from larger cohorts of women with uncorrected CHD. Methods The 10-year data from the European Society of Cardiology EORP ROPAC (EURObservational Research Programme Registry of Pregnancy and Cardiac disease) registry of women with uncorrected CHD were analyzed. Results Of 5,739 pregnancies in 53 countries, 3,295 women had CHD, 1,059 of which were uncorrected cases. Of these, 41.4% were from emerging countries. There were marked differences between the cardiac defects in uncorrected cases versus those in corrected CHD cases with primary shunt lesions (44.7% vs. 32.4%, respectively), valvular abnormalities (33.5% vs. 12.6%, respectively), and Tetralogy of Fallot and pulmonary atresia (0.8% vs. 20.3%, respectively; p < 0.001). In patients with uncorrected CHD, 6.8% were in modified World Health Organization risk class IV, approximately 10% had pulmonary hypertension (PH), and 3% were cyanotic prior to pregnancy. Maternal mortality and heart failure (HF) in the women with uncorrected CHD were 0.7% and 8.7%, respectively. Eisenmenger syndrome was associated with a very high risk of cardiac events (65.5%), maternal mortality (10.3%), and HF (48.3%). Coming from an emerging country was associated with higher pre-pregnancy signs of HF, PH, and cyanosis (p < 0.001) and worse maternal and fetal outcomes, with a 3-fold higher rate of hospital admissions for cardiac events and intrauterine growth retardation (p < 0.001). Conclusions Marked differences between cardiac conditions in pregnant women with uncorrected CHD and those in corrected CHD were found, with a markedly worse outcome, particularly in women with Eisenmenger syndrome and from emerging countries.