What Causes Tetralogy of Fallot?

Doctors don't know what causes most cases of tetralogy of Fallot and other congenital heart defects.

Having some conditions or factors during pregnancy may raise your risk for having a child with tetralogy of Fallot. These conditions and factors include:

• German measles (rubella) and some other viral illnesses
• Poor nutrition
• Overuse of alcohol
• Age (being older than 40)
• Diabetes

Heredity may play a role in this heart defect. An adult with tetralogy of Fallot may have an increased chance of having a baby with this defect.

Children with genetic disorders, such as Down syndrome and DiGeorge syndrome, often have congenital heart defects, including tetralogy of Fallot.

Scientists continue to search for the causes of tetralogy of Fallot and other congenital heart defects.