Teratogen: (teˈratəjən) noun.
An agent or factor that causes malformation of an embryo.
Chemical Teratogens
Many substances can affect the development of an embryo. Prescription and over the counter pharmaceuticals are generally considered safe, but when an embryo is forming they can be just as dangerous as street drugs, alcohol and cigarettes.
Pharmaceuticals
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It is impossible to ethically study the risk of a drug to an embryo or fetus. Most data on hazardous interactions between a pharmaceutical and a developing embryo are due to drawing correlations after a child has been born with birth defects. This was the case with the thalidomide tragedy of the 1960's. A prescription to help with morning sickness in pregnant mothers caused limb malformation​ in the developing embryos, only witnessed after the birth of the infant. For most prescription drugs, a physician must weight the health of the mother and her ability to carry her child against the potential teratogenic effects of the medicine. Over-the-counter drugs and supplements also have the potential to harm an embryo during organogenesis. Obstetricians can advise pregnant mothers on what OTC medications should be avoided.
Illegal Drugs
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The effects of the most popular street drugs on the infants of addicted mothers are well-documented, but that does not mean they are well-understood. The amount and frequency of drug use can not be correctly documented after the fact. Many addicted mothers may raise a child in a state of neglect. These all affect the development of the
child when it is assessed. What we can document is the state of the child at birth or miscarriage. Infants go through withdrawal. When other babies are interacting with their environment and their brains are making gigantic leaps in associations, these babies are suffering tremors, vomiting, convulsions and sleep problems. It is recommended to avoid all illegal drugs during pregnancy. Note: Marijuana has been made legal in a number of states, but there is evidence to indicate it is not safe while pregnant.
Tobacco and Alcohol
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Tobacco and Alcohol are both commonly consumed by the non-pregnant population. They have known risks, but their consumption is largely seen as social and legal. In the body of a pregnant woman, these substances can have a severe effect on her unborn child. Smoking's affect on birth weight is well-documented. There is also evidence to indicate a connection between social and academic development and a fetus whose mother smoked during pregnancy. Alcohol consumption during pregnancy can cause Fetal Alcohol Syndrome. This complex disorder causes physical deformities
and social and intellectual disabilities. FAS is one of the most frequent causes of clinical retardation in the United States.