Many birth defects affect the heart. About 1 in every 100 to 200 babies is born with a heart defect. Heart defects make up about one-third to one-fourth of all birth defects. Some of these heart defects can be serious, and a few are very severe. In some places of the world, heart defects cause half of all deaths from birth defects in children less than 1 year of age.
Other common birth defects are "neural tube defects," which are defects of the spine (spina bifida) and brain (anencephaly). They affect about 1 of 1,000 pregnancies. These defects can be serious and are often life threatening. They happen less often than heart defects, but they cause many fetal and infant deaths.
Birth defects of the lip and roof of the mouth are also common. These birth defects, known as "orofacial clefts," include cleft lip, cleft palate, and combined cleft lip and cleft palate. Cleft lip is more common than cleft palate. In many places of the world, orofacial clefts affect about 1 in 700 to 1,000 babies.
Some birth defects are common but rarely life threatening, though they often require medical and surgical attention. "Hypospadias," for example, is a fairly common defect found in male babies. In babies with hypospadias, the opening of the urethra (where urine comes out) is not at the tip of the penis but on the underside. Treatment depends on how far away from the tip the opening is and can involve complex surgery. This defect is rarely as serious as the others listed above, but it can cause great concern and sometimes has high medical costs. It rarely causes death.
These are only some of the most common birth defects. Two final points are worth noting. First, genetic conditions, though not mentioned so far, also occur often. Down syndrome, for example, is a genetic condition that affects about 1 in 800 babies, but it affects many more babies who are born to older women. Second, a woman who is pregnant may miscarry a baby (fetus) early, before it is time for the baby to be born. This often happens when the fetus has a severe birth defect. To know the true impact of birth defects and how often they occur, we not only need to look at babies born but also, if possible, look at all pregnancies.