What is a teratogen?

• A. Anything that causes harmful development in the unborn child.
• B. A substance that protects fetal development.
• C. A stage of prenatal development.
• D. A genetic mutation causing birth defects.

Answer: (A)

Teratogens are agents that can cause harm to a developing fetus during pregnancy. They include substances like certain medications, alcohol, environmental chemicals, infections, and radiation. The idea is that these factors have the potential to disrupt normal development, leading to birth defects, growth problems, or pregnancy loss, depending on when exposure happens and how much exposure occurs. For example, exposure during early pregnancy can affect organ formation and lead to defects, while higher doses or exposure at sensitive periods can have more severe effects. Some exposures may have minimal impact if timing or dose differs. It’s not about something that protects development, nor a stage of prenatal development, nor a genetic mutation—teratogens are external factors that can harm development if the fetus is exposed.