Home > Encyclopedia of Science > Birth Defects

• Chromosomal abnormalities
• Inherited disorders
• Words to Know
• Physical birth defects
• Environmental factors
• Prenatal testing
• Apgar Score

Birth defects, or congenital defects, are abnormalities that are present at birth. They may be the result of genetic factors such as an inherited disease or a chromosomal abnormality. They may also be caused by environmental factors such as radiation, the mother's use of drugs or alcohol while pregnant, or bacterial or viral infections.

Birth defects can range from very minor, such as a birthmark, to a more serious condition that results in physical deformity or limits the lifespan of the child. Two to...