Dysmorphology

Teratology is the study of abnormalities of physiological development. It is often thought of as the study of human congenital abnormalities, but it is broader than that, taking into account other non-birth developmental stages, including puberty; and other non-human life forms, including plants. The related term developmental toxicity includes all manifestations of abnormal development that are caused by environmental insult. These may include growth retardation, delayed mental development or other congenital disorders without any structural malformations.

Teratogens are substances that may cause birth defects via a toxic effect on an embryo or foetus.

The term teratology stems from the Greek τέρας teras (genitive τέρατος teratos), meaning "monster" or "marvel", and λόγος logos, meaning "the word" or, more loosely, "the study of".

As early as the 17th century, teratology referred to a discourse on prodigies and marvels of anything so extraordinary as to seem abnormal. In the 19th century it acquired a meaning more closely related to biological deformities, mostly in the field of botany. Currently, its most instrumental meaning is that of the medical study of teratogenesis, congenital malformations or individuals with significant malformations. Historically, people have used many pejorative terms to describe/label cases of significant physical malformations. In the 1960s David W. Smith of the University of Washington Medical School (one of the researchers who became known in 1973 for the discovery of fetal alcohol syndrome), popularized the term teratology. With the growth of understanding of the origins of birth defects, the field of teratology as of 2015^[update] overlaps with other fields of science, including developmental biology, embryology, and genetics. Until the 1940s teratologists regarded birth defects as primarily hereditary. In 1941 the first well-documented cases of environmental agents being the cause of severe birth defects were reported.

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