Cause
Doctors are unsure of the cause of congenital heart defects, but there are some medical conditions that have been found to increase the risk of having a baby with a heart defect such as congenital heart disease in the mother, father, brother, or sister of the baby, a diabetic mother, use of drugs or alcohol or over the counter prescriptions during pregnancy. These conditions do not mean that the baby will definitely be born with a heart defect, but that it runs a higher chance. Sometimes babies are born without any of these conditions; the cause is unknown.
Read more about this topic: Pulmonary Atresia