Causes and Risk Factors for Congenital Heart Defects

In most cases (as many as 90 percent), the cause for the congenital heart defect is unknown. Of the approximately 10–15 percent of cases in which the cause can be determined, one of the following circumstances may be the cause for the condition.

Chromosomal Abnormalities and Genetic Disorders

About 5–8 percent of all congenital heart defects occur in babies born with Down syndrome or other chromosomal abnormalities, such as Turner syndrome, trisomy 18, trisomy 13, DiGeorge sequence, Cri du chat syndrome, Velo-cardio-facial syndrome, Wolf-Hirchhorn syndrome, and Williams syndrome.

Inherited disorders such as Noonan syndrome, Holt-Oram syndrome, Marfan syndrome, Smith-Lemli-Opitz syndrome, Ellis-van Creveld, and mucopolysaccharidoses can also be accompanied by congenital heart defects.

Exposure to Certain Viruses or Medications during Pregnancy

Babies born to mothers who were infected with rubella (German measles) during the first 3 months of pregnancy often are born with congenital heart defects. Certain strains of flu virus contracted during pregnancy can also have an affect on the heart development of a fetus.

Exposure to certain prescription drugs, use of illegal drugs, alcohol, or contact with other toxic substances during pregnancy can cause congenital heart defects. Certain anti-seizure medications and lithium (used to treat bipolar disorder) may increase the risk for having a baby with a congenital heart defect. Exposure to certain chemicals (e.g., pesticides, solvents) during pregnancy also may increase the risk for congenital heart defects.

Chronic Health Conditions and Congenital Heart Defects

Certain chronic health conditions (e.g., diabetes, lupus) during pregnancy can increase the risk for congenital heart defects. Women with diabetes may be at a higher risk for having a baby born with a congenital heart defect, especially if the condition is not managed properly during pregnancy.

Publication Review By: Stanley J. Swierzewski, III, M.D.

Published: 18 Nov 2008

Last Modified: 08 Sep 2015