Certain chronic illnesses in the mother also can increase the risk of heart defects. For example, women with diabetes are at increased risk of having a baby with a heart defect, although this risk can be reduced or eliminated if the diabetes is closely controlled starting before pregnancy. While most families have no more than one child with a heart defect, these malformations are more likely to occur in siblings or offspring of people who have heart defects than in unaffected families. This suggests that genetics plays a role in heart defects, at least in these families. However, scientists also have pinpointed several mutations that affect the formation of the heart, leading to congenital heart malformations.
Researchers appear to be on the brink of discovering the genes that underlie numerous heart defects.
Heart defects also can be part of a wider pattern of birth defects. For example, more than one-third of children with Down syndrome have heart defects. The outlook has never been brighter for babies and children with congenital heart defects. Today, most heart defects can be corrected, or at least helped, by surgery, medicine or devices such as artificial valves and pacemakers. In the last 25 years, advances in treatment of heart defects have enabled half a million U.S. children with significant heart defects to survive into adulthood.