What Are the Causes of Congenital Heart Disease?

A condition affecting 32,000 newborns annually in the United States alone, the specific causes of congenital heart disease are often unknown. But physicians are able to occasionally cite genetic or environmental factors contributing to heart defects.

Types

• Congenital heart disease is an abnormality of the heart muscle that is present at birth rather than developing over time. "Some types of congenital heart defects can be related to an abnormality of an infant's chromosomes (5 to 6 percent), single gene defects (3 to 5 percent), or environmental factors (2 percent)," according to Children's Hospital Boston.

Identification

• In 85 to 90 percent of cases the exact causes of congenital heart disease are unknown, indicating a combination of environmental, genetic and other conditions.

Genetics

• "Children who have genetic disorders, such as Down syndrome, often have congenital heart defects," according to The National Heart Lung and Blood Institute. Researchers have discovered at least 10 types of gene mutations that result in heart defects.

Environmental

• Environmental issues such as smoking during pregnancy, alcohol consumption, poor blood sugar levels in pregnant diabetics, medications and street drugs used during pregnancy increase the likelihood of congenital heart defects.

Illnesses

• Environmental issues also include maternal illnesses like flu and rubella. "Women who contract rubella (German measles) during the first three months of pregnancy have a high risk of having a baby with a heart defect," according to the March of Dimes Foundation.