Nine out of every 1,000 babies born in the United States have 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 common birth defects.

A baby's heart begins to develop at conception, but is completely formed by eight weeks into the pregnancy. Congenital heart defects happen during this crucial first eight weeks of the baby's development. Specific steps must take place in order for the heart to form correctly. Often, congenital heart defects are a result of one of these crucial steps not happening at the right time, leaving a hole where a dividing wall should have formed, or a single blood vessel where two ought to be, for example.

What causes congenital heart disease?

The vast majority of congenital heart defects have no known cause. Mothers will often wonder if something they did during the pregnancy caused the heart problem. In most cases, nothing can be attributed to the heart defect. Some heart problems do occur more often in families, so there may be a genetic link to some heart defects. Some heart problems are likely to occur if the mother had a disease while pregnant and was taking medications, such as anti-seizure medicines. However, most of the time, there is no identifiable reason as to why the heart defect occurred.

Congenital heart problems range from simple to complex. Some heart problems can be watched by the baby's physician and managed with medicines, while others will require surgery, sometimes as soon as in the first few hours after birth. A baby may even "grow out" of some of the simpler heart problems, such as patent ductus arteriosus (PDA) or ventricular septal defect (VSD), since these defects may simply close up on their own with growth. Other babies will have a combination of defects and require several operations throughout their lives.

What are the different types of congenital heart defects?

We can classify congenital heart defects into several categories in order to better understand the problems the baby will experience. They include:

• problems that cause too much blood to pass through the lungs
  These defects allow oxygen-rich blood that should be traveling to the body to re-circulate through the lungs, causing increased pressure and stress in the lungs.

• problems that cause too little blood to pass through the lungs
  These defects allow blood that has not been to the lungs to pick up oxygen (and, therefore, is oxygen-poor) to travel to the body. The body does not receive enough oxygen with these heart problems, and the baby will be cyanotic(have a blue coloring).

• problems that cause too little blood to travel to the body
  These defects are a result of underdeveloped chambers of the heart or blockages in blood vessels that prevent the proper amount of blood from traveling to the body to meet its needs.

Again, in some cases there will be a combination of several heart defects, making for a more complex problem that can fall into several of these categories.

For more information about specific defects please click on link, heart defects.