Congenital Heart Defects (CHD) are problems with the structure of the heart that are present at birth. They occur early in the pregnancy as the heart is being formed. The defects may involve heart valves, blood vessels, the walls between the chambers of the heart, or the development of the heart. CHDs are the most common major birth defects, and although they can be fatal, improvements in surgical and diagnostic techniques have made that outcome less common in recent years.

