Doctors often don't know what causes tetralogy of Fallot and other congenital heart defects.
Some conditions or factors that occur during pregnancy may raise your risk of having a child who has tetralogy of Fallot. These conditions and factors include:
- German measles (rubella) and some other viral illnesses
- Poor nutrition
- Alcohol use
- Age (being older than 40)
Heredity may play a role in causing tetralogy of Fallot. An adult who has tetralogy of Fallot may be more likely than other people to have a baby with the condition.
Researchers continue to search for the causes of tetralogy of Fallot and other congenital heart defects.