Mothers of children who are born with atrial septal defects (ASDs), ventricular septal defects (VSDs), or other types of heart defects often think that they did something wrong during the pregnancy to cause the problems. However, most of the time, doctors don't know why congenital heart defects develop.
Heredity may play a role in some heart defects. For example, a parent who has a congenital heart defect is slightly more likely than other people to have a child with the problem. Very rarely, more than one child in a family is born with a heart defect.
Children who have genetic disorders, such as Down syndrome, often have congenital heart defects. Half of all babies who have Down syndrome have congenital heart defects.
Smoking during pregnancy also has been linked to several congenital heart defects, including septal defects.
Scientists continue to search for the causes of congenital heart defects.