Most adults who have holes in their hearts were born with the hole in their heart.
A hole in the heart is usually caused by a birth defect and then the hole may later get bigger as the baby grows and then turns into an adult.
There's no actual 100 percent known cause of holes in the heart but most of them do occur at birth.
However some things that can cause holes in the heart as an adult and child are.
Illnesses your mother contracted while she was pregnant, such as German measles.
Medication your mother took while pregnant.
Genetic causes, meaning the heart condition runs in your family.
Some people with congenital heart disease aren’t diagnosed until they reach adolescence or adulthood.
Others are diagnosed and treated for congenital heart defects as babies or children.