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Congenital heart defects happen because the heart does not develop normally while the baby is growing in the womb. Doctors often do not know why congenital heart defects occur. Researchers do know that genetics can sometimes play a role.
It is common for congenital heart defects to occur because of changes in the child’s DNA. The changes in the DNA may or may not have come from the parents.
Rarely, congenital heart defects are caused by particular genes that are inherited from the parents. That means a parent who has a congenital heart defect may have an increased risk of having a child with the defect.