Congenital heart disease (CHD) is the most common congenital malformation, accounting for about 1% of live births. The word “congenital” means existing at birth. A congenital heart defect can involve the walls or valves of the heart, or the arteries and veins near the heart. These structural anomalies can disrupt the normal flow of blood through the heart, causing it to slow down, go in the wrong direction or to the wrong place, be blocked completely. Often, no known cause is found, but viral infections and certain inherited conditions or genetic syndromes can increase the risk of a baby to develop CHD. Fetal exposure to drugs or alcohol may also increase the risk. There are many types of CHD, ranging from simple to very complex.