Epidemiology of Congenital Heart Defects in Live Births: Findings from a Study in Southern Brazil

Background Congenital heart defects (CHD) are the leading cause of infant mortality associated with birth defects in Brazil. Access to prenatal diagnosis is still considered low, and treatment is limited to referral centers, especially in large urban centers. Objectives To characterize the profile of live births diagnosed with CHD in three university hospitals in Rio Grande do Sul, a state in southern Brazil. Methodology: This study was based on an active surveillance system, and data were collected between November 2021 and February 2024 through medical record searches and maternal interviews. Statistical differences between CHD and maternal risk factors during pregnancy and neonatal variables were assessed using Fisher's exact test and Poisson regression with robust variance. Results From 381 CHD cases identified, 64.3% were classified as isolated (iCHD) and 35.7% as associated with other anomalies or syndromes (aCHD). The most frequent CHD was atrial and ventricular septal defects. Down syndrome was the most common genetic condition observed among associated cases. Maternal age, low birth weight and infant mortality were significantly more frequent in the aCHD group. Illicit drug use was more frequent in the iCHD. The rate of prenatal diagnosis by fetal echocardiography was low (15%) in both groups, and the rate of false negative results was high 14 (7.5%) iCHD and 17 (15.9%). Mortality was observed in the iCHD (n = 9; 3.7%) and in the aCHD group (n = 24; 17.8%). Conclusions These findings highlight the importance of improving access to specialized prenatal care and implementing multidisciplinary strategies for managing CHD.