Teratogen Health Dictionary

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Teratogen: From 2 Different Sources

A physical, chemical, or biological agent, such as radiation, the drug thalidomide, and the rubella virus, that causes abnormalities in a developing embryo or fetus.
Health Source: BMA Medical Dictionary
Author: The British Medical Association
n. any substance, agent, or process that induces the formation of developmental abnormalities in a fetus. Known teratogens include such drugs as *thalidomide and alcohol; such infections as German measles and cytomegalovirus; and also irradiation with X-rays and other ionizing radiation. Compare mutagen. —teratogenic adj.
Health Source: Oxford | Concise Colour Medical Dictionary
Author: Jonathan Law, Elizabeth Martin

Teratogenesis

The production of physical defects in the FETUS. A drug may interfere with a mechanism that is essential for growth, and result in arrested or distorted development of the fetus – and yet cause no disturbance in adults, in whom these growth processes have ceased. Whether and how the EMBRYO is affected depends on what stage of development it has reached when the drug is given. The age of early di?erentiation – that is, from the beginning of the third week to the end of the tenth week of pregnancy – is the time of greatest susceptibility. After this time the likelihood of CONGENITAL malformation resulting from drug treatment is less, although the death of the fetus can occur at any time as a result of drugs crossing the PLACENTA or as a result of their e?ect on the placental circulation.

Although the risks are nil or very small with most drugs, no medication should be given to a pregnant woman, particularly during the ?rst few months of pregnancy, unless it is absolutely essential for her health or that of her unborn child. Alcohol is regarded as ‘medication’ in this context.... teratogenesis


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