Birth prevalence of congenital heart defects in Norway 1994-2009--a nationwide study.

BACKGROUND The reasons for decreasing birth prevalence of congenital heart defects (CHDs) in several European countries and Canada are not fully understood. We present CHD prevalence among live births, stillbirths, and terminated pregnancies in an entire nation over a period of 16 years. METHODS Information on all births in the Medical Birth Registry of Norway, 1994-2009, was updated with information on CHD from the hospitals' Patient Administrative Systems, the National Hospital's clinical database for children with heart disease, and the Cause of Death Registry. Individuals with heart defects were assigned specific cardiac phenotypes. RESULTS Among 954,413 births, 13,081 received a diagnosis of CHD (137.1 per 10,000 births, 133.2 per 10,000 live births). The prevalence per 10,000 births was as follows: heterotaxia, 1.6; conotruncal defects, 11.6; atrioventricular septal defects, 5.6; anomalous pulmonary venous return, 1.1; left outflow obstructions, 8.7; right outflow obstructions, 5.6; septal defects, 65.5; isolated patent ductus arteriosus, 24.6; and other specified or unspecified CHD, 12.7. Excluding preterm patent ductus arteriosus, the CHD prevalence was 123.4 per 10,000; per year, the prevalence increased with 3.5% (95% CI 2.5-4.4) in 1994-2005 and declined with 9.8% (-16.7 to -2.4) from 2005 onwards. Severe CHD prevalence was 30.7 per 10,000; per-year increase was 2.3% (1.1-3.5) in 1994-2004, and per-year decrease was 3.4% (-6.6 to -0.0) in 2004-2009. Numbers included severe CHD in stillbirths and terminated pregnancies. CONCLUSIONS The birth prevalence of CHD declined from around 2005. Specifically, the prevalence of severe CHD was reduced by 3.4% per year from 2004 through 2009.