birth defects

birth defects abnormalities in physical or mental structure or function that are present at birth. They range from minor to seriously deforming or life-threatening. A major defect of some type occurs in approximately 3% of all births. Defects may be genetic in origin, as in Down syndrome , Tay-Sachs disease , sickle cell disease , and hemophilia , or may be the result of infections, such as rubella and sexually transmitted diseases . Other teratogenic (malformation-causing) agents include drugs or hormones taken by the mother (e.g., thalidomide and DES ) and maternal illnesses (e.g., diabetes ). The mother's nutrition, drinking (see fetal alcohol syndrome ), smoking , and drug abuse, as well as exposure to toxic chemicals and radiation, can also affect the developing fetus. Smoking, drugs, toxic chemicals, and the like can also damage the father's sperm, which may pass on the defect to the embryo in fertilization. The incidence of some disorders is elevated when the mother or father is older, which increases the likelihood of age-related gene mutations. Certain birth defects can now be detected prenatally through amniocentesis and chorionic villus sampling . Surgical procedures to correct certain disorders before birth are still considered experimental.

birth defects This term refers broadly to anything that is wrong with an infant at birth, whether it be a true congenital abnormality resulting from maldevelopment of the fetus in utero (from either inherent genetic or extraneous causes) or damage to the normally-developed fetus by infection or injury before or during birth. The term may cover both those defects which are evident at the time of birth and also those which reveal themselves later, including inborn errors of metabolism.

Stuart Judge