Abstract Background and Aims Angiotensin-converting enzyme inhibitors (ACE-Is) and angiotensin receptor blockers (ARBs) are not recommended during the second and third trimester due to the significant risk of congenital anomalies associated with their use. However, data are scarce, especially regarding their use in the first trimester. Our study illustrates the profile of the women who used ACE-Is or ARBs during pregnancy and to evaluate the impact on perinatal outcomes. Methods The Registry of Pregnancy and Cardiac disease (ROPAC) is a prospective, global registry of pregnancies in women with structural heart disease. Outcomes were compared between women who used ACE-Is or ARBs and those who did not. Multivariable regression analysis was performed to assess the effect of ACE-I or ARB use on the occurrence of congenital anomalies. In addition, the perinatal outcomes of patients who stopped ACE-Is and/or ARBs before pregnancy were assessed. Results ACE-I (n=35) and/or ARB (n=8) were used in 42 (0.7%) of the 5739 ROPAC pregnancies. Women who used ACE-Is or ARBs more often came from a low-or-middle-income country (57% vs 40%, p=0.021), had chronic hypertension (31% vs 6%, p<0.001), or a left ventricular ejection fraction <40% (33% vs 4%, p<0.001). No pregnancy terminations due to fetal anomaly were reported. ACE-I use during the first trimester was independently associated with an increased risk of congenital anomaly (OR 3.1; 95% CI 1.0-9.3). No adverse fetal or neonatal effects were seen when ACE-I and/or ARB were discontinued prior to pregnancy. Conclusions ACE-Is and ARBs are seldom used during pregnancy and based on our data, ACE-Is should also be avoided in the first trimester due to a higher risk of congenital anomalies. Preconception counseling is crucial to discuss the potential risks of these medications, and to evaluate the clinical condition and, if possible, the woman can be switched to an alternative medication.