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“Congenital” refers to the existence of a disorder before or at birth. Congenital defects include birth defects or a variety of other disorders. Roughly 380,000 births occur each year in Canada. About 350 to 400 babies are born with some kind of defect, including 50 to 150 with heart defects, for every 10,000 total births. Fort McKay, with a population less than 900, would be expected to experience a heart-defect case at some point, although rarely.

Causes of heart defects involve many factors. As well, it is a polygenic inherited disorder (meaning an inheritance pattern controlled by many genes). In most cases there is no clearly identifiable cause for a heart defect.

The Public Health Agency of Canada lists heart-defect causes. Genetic causes are chromosomal syndromes and single gene disorders. Non-genetic causes include: maternal rubella during pregnancy, supplements and medication use during pregnancy (for example, anti-epileptics or thalidomide), or glycemic control for diabetes during pregnancy. Other possible causes during pregnancy are maternal illnesses (for example, influenza), therapeutic drug use (such as anti-viral or antifungal agents), marijuana and cocaine use, cigarette smoking, chemical exposures (solvent addiction or overexposure to herbicides or pesticides) and socio-demographic factors (race/ethnicity, maternal age). Industrial pollution did not rise to the level of importance to be listed as a cause.