Trends in Birth Prevalence of Congenital Heart Defects in Norway-A Population Study 1994-2014.

Aim: The prevalence of severe congenital heart defects (CHDs) has been declining in Europe, possibly because pregnancies with foetal anomalies are often terminated. We present trends in the prevalence of CHD among live births, stillbirths and terminated pregnancies over a 21-year period in Norway.

Method: All births and terminated pregnancies registered in Norway's Medical Birth Registry from 1994-2014 were linked to information on CHDs and extracardiac birth defects or chromosomal aberrations found in national administrative and clinical registries.

Results: We identified 18 838 individuals with CHD among the 1 261 952 live births, stillbirths and terminated pregnancies, which was 149.3 per 10 000. In live births, the CHD prevalence was 144.6 per 10 000. The prevalence of severe CHD increased from 27.1 in 1994 to 36.1 in 2004, then declined to 27.8 in 2014, with an overall prevalence of 32.1 per 10 000. In live births, the prevalence was 29.0 per 10 000. The prevalence of severe CHD in nonsyndromic births was 20.4 per 10 000, with no time trend. Septal defects increased continuously after 1994.

Conclusion: From 2004-2014, the prevalence of severe CHD declined, primarily due to a decrease in syndromic CHD. This could likely be explained by pregnancy terminations. Septal defects increased over the entire study period.