Teratogenic

Teratogenic refers to any agent or factor that induces or increases the incidence of abnormal prenatal development. The term originates from the Greek words "teras" or "teratos," meaning monster, and "genes," meaning born of, produced by, or pertaining to. Teratogens may cause a birth defect or may halt the pregnancy outright. The classes of teratogens include radiation, maternal infections, chemicals, and drugs.

Types of Teratogens

Teratogens are classified into four types: physical agents, metabolic conditions, infectious diseases, and drugs or chemicals.

Physical Agents

Physical agents that can cause birth defects include radiation, hyperthermia, and mechanical factors. Radiation is known to cause birth defects, especially if exposure occurs during the first trimester of pregnancy. Hyperthermia, or high maternal body temperature, can also cause birth defects, particularly neural tube defects. Mechanical factors, such as constraint within the uterus, can lead to physical deformities.

Metabolic Conditions

Certain maternal metabolic conditions, such as diabetes and phenylketonuria, can act as teratogens and cause birth defects. Women with poorly controlled diabetes have a higher risk of having a child with birth defects, especially heart and neural tube defects. Phenylketonuria, a genetic disorder that increases the body's levels of phenylalanine, can cause intellectual disability, microcephaly, and heart defects if not properly managed during pregnancy.

Infectious Diseases

Infectious diseases can also act as teratogens. Some of the most common infectious teratogens are the TORCH infections, which include Toxoplasmosis, Other (syphilis, varicella-zoster, parvovirus B19), Rubella, Cytomegalovirus, and Herpes simplex virus.

Drugs and Chemicals

Many drugs and chemicals can act as teratogens. These include alcohol, retinoic acid, thalidomide, and certain antiepileptic drugs. Alcohol is one of the most common teratogens and can cause a range of physical and mental birth defects, a condition known as fetal alcohol syndrome. Retinoic acid, a form of vitamin A, can cause birth defects if taken in excess during pregnancy. Thalidomide, a drug once used for morning sickness, is a potent teratogen and can cause severe limb defects.

Prevention

Prevention of teratogenic effects largely involves avoiding known teratogens during pregnancy, including harmful medications, alcohol, illicit drugs, and infectious agents. Women planning to become pregnant should also ensure they are in good health and manage any chronic conditions, as some can act as teratogens.

See Also

• Birth defect
• Fetal alcohol syndrome
• TORCH infections
• Thalidomide

Teratogenic Resources
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