Some babies enter the world with a heart problem. Eight of every 1,000 children have a heart defect present at birth, otherwise known as congenital heart disease. Defects range from problems with heart valves closing or leaking to abnormalities in the heart muscle. In some instances, doctors will be able to spot the problem while the baby is still in the womb, while most cases are diagnosed at birth or shortly thereafter. It's possible, though, that the defect may not be detected until childhood or even adulthood. That's because many defects are symptomless and even harmless; some don't even require treatment. Sometimes, though, patients with congenital heart disease may need medications or, rarely, surgery. There's no one reason why congenital heart disease occurs. It may have something to do with genetics, infections experienced by an expecting mother, or exposure to alcohol and drugs while in the womb.