Congenital anomalies in pregnancies with overt and pregestational type 2 diabetes: a gray portrayal from a cohort in Brazil

Abstract Objective To describe the frequency and types of congenital anomalies and associated risk factors in Brazilian women with type 2 diabetes. Methods In this retrospective cohort study between 2005 and 2021, we included all pregnant participants with type 2 diabetes from the two major public hospitals in southern Brazil. We collected data from the electronic hospital records. Congenital anomalies were classified by the 10th revised International Classification of Diseases, Q chapter, enhanced by the EUROCAT registry classification, and categorized by type and gravity. We used multiple Poisson regression with robust estimates to estimate risks. Results Among 648 participants, we excluded 19, and 62 were lost to follow-up; therefore, we included 567 participants. Overt diabetes arose in 191 participants (33.7%, 95% CI 30.0% – 38.0%). Less than 20% of the participants supplemented folate. Congenital anomalies occurred in 78 neonates (13.8%, CI 11.0 − 16.9%), 73 babies (93.6%) presented major anomalies, and 20 (10.5%) cases occurred in participants with overt diabetes. Cardiac anomalies were the most frequent (43 isolated and 12 combined). Pre-eclampsia was associated with an increased risk in the analyses including all women (adjusted RR 1.87 (95% CI 1.23–2.85), p = 0.003), but not in analyses including only women with an HbA1c measured up to the 14th gestational age. HbA1c, either measured at any time in pregnancy (adjusted RR 1.21 (95% CI 1.10–1.33), p < 0.001) or up to the first 14 weeks (adjusted RR 1.22, 95% CI 1.10–1.35, p < 0.001) was the only sustained risk factor. Risk factors such as maternal age, obesity, diabetes diagnosis, or use of antidiabetic medications were not associated with congenital anomalies. Conclusion We found a high frequency of congenital anomalies associated with poor maternal glycemic control and revealed an almost universal lack of preconception care. An urgent call to action is mandatory for the reversal of this gray scenario.