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.

The increased risk of having a child with a congenital heart defect has not changed for diabetic women in Norway since 1994. Among women with pregestational or gestational diabetes, having a large-for-gestational-age neonate was associated with a two- to threefold increased risk of cardiac defects compared with neonates with normal birth weight.