One out of every 100 infants born in the United States has a congenital (present at birth) heart defect -- a problem that occurred as the baby’s heart was developing during pregnancy, before the baby is born. Congenital heart defects are the most commonly occurring birth defect.

A baby's heart begins to develop at conception, and is completely formed by eight weeks into the pregnancy. Congenital heart defects happen during these crucial first eight weeks of the baby’s development. 

Often, congenital heart defects are a result of these crucial steps not happening at the right time, or in the correct order, which means the child may be born with a single blood vessel where two ought to be or a communication (hole) between two heart chambers that should be separate.