An agent or a substance that may cause physical defects in the developing embryo or fetus when a pregnant female is exposed to the substances is called what?

• A. Carcinogen
• B. Teratogen
• C. Lethal Dose
• D. Effective Dose

Answer: (B)

Teratogen is the term for any agent that can cause birth defects or abnormal development in an embryo or fetus when a pregnant person is exposed. The effect depends on the timing of exposure—early pregnancy, when organs are forming, is the most sensitive period—so a substance might produce structural malformations or functional issues. The risk also depends on dose and duration; not every exposure causes defects, but higher or prolonged exposure during critical windows increases the chance of problems. This concept is distinct from carcinogens (which are linked to cancer), lethal doses (the amount that can cause death), and effective doses (the amount needed to achieve a therapeutic or desired effect).