Birth defects: what they are and how they happen

Birth defects are health conditions that are present at birth. Birth defects change the shape or function of one or more parts of the body. They can cause problems in overall health, how the body develops, or in how the body works.

There are thousands of different birth defects. About 120,000 babies in the United States are born each year with a birth defect. The most common birth defects are heart defects, cleft lip and cleft palate, Down syndrome and spina bifida. While there’s been lots of research, we still don’t know the causes of some birth defects.

If a woman drinks alcohol during pregnancy, her baby may have a birth defect. Some street drugs and some prescription drugs can cause birth defects, too. Also, if a woman gets certain infections during pregnancy, such as cytomegalovirus or a sexually transmitted infection, her baby may develop a birth defect.

Some birth defects are caused by genetic conditions. Genetic conditions are passed from parents to children through genes. The baby could get something from his mother, his father, or both parents that can cause a birth defect.