Birth Defects, sometimes called congenital anomalies, are abnormalities in the structure of organs that are present at birth. Typically the abnormalities involve a body part that is missing or malformed. Other birth defects involve problems with metabolism, or how the organs work. The MA Center collects data only on structural abnormalities. Birth defects can affect any system in the body. Some babies have just one defect while others may have multiple defects. The most common birth defects include:
  • Heart defects
  • Genitourinary defects
  • Cleft lip/palate
  • Chromosome problems
  • Abdomen and chest defects
  • Limb abnormalities
  • Brain and nervous system abnormalities
  • Gastrointestinal

1. We don't know what causes most birth defects.

  • Fewer than 10% of birth defects result from prenatal exposures to known hazards. German measles, diabetes or heavy drinking of alcohol during pregnancy are some exposures that can cause birth defects.

  • Some are the result of abnormal genes or chromosomes that may be inherited or may represent new mutations.

  • Most birth defects are thought to arise from interactions between genes or interactions between genes and environmental factors. Certain chemicals may affect some families more than others.

  • 70% of birth defects are of unknown cause.

2. Birth defects can occur even when prenatal care is very good.

  • Prenatal care has been shown to be very important to the health of both mother and baby, however it has little impact on birth defects. Major embryonic development occurs in the first few weeks of a pregnancy, often before a woman knows she is pregnant.

  • Research has shown that taking a multivitamin containing folic acid, a B vitamin, before conception and for the first several months lowers the risk for a type of birth defect called neural tube defects.

3. Birth defects can happen in any family.

  • Birth defects can happen to babies born to mothers of all ages, race/ethnic groups, education levels.


This information is provided by the Center for Birth Defects Research and Prevention within the Department of Public Health.