Background: Few studies have assessed the prevalence and mortality of simple or complex congenital heart diseases (CHD) in newborns. In Latin America and Caribbean (LAC), CHD epidemiology seems highly variable, with few population-based assessments and different methodologies between studies. To date, the situation in French Guiana, a French overseas territory located in South America between Brazil and Suriname, has never been described.

Methods: We analysed CHD prevalence, characteristics and related infant mortality in French Guiana, with a population-based registry analysis of all fetal and live birth CHD cases in infants under 1 year (January 2012-December 2016).

Findings: Overall, 33,796 births (32,975 live births) were registered, with 231 CHD (56 fetuses), including 215 live births. Most frequent CHD categories were anomalies of the ventricular outflow tract and extra-pericardial trunks, and ventricular septal defects. 18.6% (43/231) chromosomal or genetic anomalies, and 6.5% (15/231) terminations of pregnancy were observed. Total CHD prevalence was 68.4 [95% CI: 67.9-68.8] per 10,000, while live birth prevalence was 65.2 [95% CI: 64.7-65.7] per 10,000. Total infant mortality was 9.4/10,000 live births [95% CI 9.1-9.7], with highest rates for functionally univentricular hearts (FUH).

Interpretation: A distinct profile for CHD is highlighted in French Guiana with elevated mortality linked to FUH. A potential determinant of the recognized excess mortality risk might be the presence of chromosomal or genetic anomalies in about a fifth of all CHD. This helps us to better understand CHD burden in this part of South America and provides future keys towards reducing CHD-related infant mortality.