The development of structural or functional malformations in an embryo or a fetus
Abnormalities in structural or physiological aspects of a developing embryo or fetus may be due to exposure or administration of teratogens. Teratogenesis refers to the induction or production of malformations in a developing embryo or fetus. Teratogens are substances that may cause birth defects.1 The study of this type of abnormalities is called teratology and experts in this field is referred to as teratologist.
The mechanism of teratogenesis is not yet well-founded. However, the two major outcomes of exposure to teratogens are death of the embryo or the fetus or the formations of congenital abnormalities. Teratogens may act directly on the developing embryo or they may indirectly cause damage to the embryo by causing maternal toxicity and deprive the embryo of adequate oxygen or nutrients. An example of a teratogen is alcohol. Chronic alcohol consumption during pregnancy could delay mental development depending on the amount of alcohol ingested. Consumption of more than 1 ounce of ethyl alcohol daily by the mother would risk her child acquiring fetal alcohol syndrome.
Word origin: Ancient Greek téras (“monster”) + Ancient Greek genesis (“origin”)
1 Thall Bastow BD, Holmes JL (23 February 2016). “Teratology and drug use during pregnancy”. Medscape. WebMD. Retrieved 24 February 2016.