Which statement best defines a teratogen and provides an example?

Which statement best defines a teratogen and provides an example?

• A. A teratogen is an agent that can disturb fetal development; examples include vitamins.
• B. A teratogen is an agent that can disturb fetal development; examples include alcohol and nicotine.
• C. A teratogen is a virus that only affects the mother but not the fetus.
• D. A teratogen is a substance that cures fetal defects.

Answer: (B)

A teratogen is any agent that can disturb fetal development when a fetus is exposed during pregnancy. Alcohol and nicotine are classic examples because they cross the placenta and can interfere with growth and development, leading to problems such as fetal growth restriction, preterm birth, and neurodevelopmental issues (in the case of alcohol, fetal alcohol spectrum disorders). The idea hinges on exposure during sensitive periods of development and on the dose and timing of exposure. Vitamins are generally nutrients that support development, and while extreme excess of certain nutrients can cause problems, they are not the typical example of teratogens. A virus can be a teratogen as well if it crosses the placenta and harms the fetus, so the statement that a virus only affects the mother isn’t accurate. A substance that cures fetal defects is not what a teratogen is.

A teratogen is any agent that can disturb fetal development when a fetus is exposed during pregnancy. Alcohol and nicotine are classic examples because they cross the placenta and can interfere with growth and development, leading to problems such as fetal growth restriction, preterm birth, and neurodevelopmental issues (in the case of alcohol, fetal alcohol spectrum disorders). The idea hinges on exposure during sensitive periods of development and on the dose and timing of exposure. Vitamins are generally nutrients that support development, and while extreme excess of certain nutrients can cause problems, they are not the typical example of teratogens. A virus can be a teratogen as well if it crosses the placenta and harms the fetus, so the statement that a virus only affects the mother isn’t accurate. A substance that cures fetal defects is not what a teratogen is.