Congenital Heart Defects

Source: MedlinePlus Health Topics, U.S. National Library of Medicine

Last synced 8/10/2026Status: primary verified

What are congenital heart defects? Congenital heart defects (CHDs) are problems with the structure of the heart. "Congenital" means that that the problems are present at birth. These defects happen when a fetus's heart doesn't develop normally during pregnancy. Congenital heart defects are the most common type of birth defect . Congenital heart defects can change the way the heart pumps blood. They may make blood flow too slowly, go the wrong way, or block it completely. There are many types of congenital heart defects. They can happen in one or more parts of the heart. The most common types are: Septal defects ("hole in the heart") - openings in the wall between the left and right sides of the heart Heart valve defects - problems with the valves that control the flow of blood through the heart Defects in the large blood vessels that carry blood in and out of the heart Congenital heart defects can range from very mild problems that never need treatment to life-threatening problems at birth. The most serious congenital heart defects are called critical congenital heart disease . Babies with these defects usually need surgery in the first year of life. But the symptoms of milder heart defects may not show up until childhood or adulthood. What causes congenital heart defects? Researchers often don't know what causes congenital heart defects. They do know that changes in a baby's genes sometimes cause a heart defect. The changed genes may come from the parents, or the changes may happen during pregnancy. Who is more likely to have a baby with a congenital heart defect? Several things may increase the chance that your baby has a congenital heart defect, such as: Your health before and during pregnancy , including: Having diabetes before pregnancy or developing it in the first 3 months of pregnancy (diabetes that develops later in pregnancy isn't a major risk for heart defects). Carefully controlling your blood glucose , also called blood sugar, before and during pregnanc

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This information is for general education and is not medical advice. Always talk to a licensed U.S. clinician about your situation, medications, or treatment decisions.