Where are teratogens primarily found?

Teratogens are substances that can cause malformations or developmental abnormalities in a fetus when a pregnant woman is exposed to them. They primarily affect pregnant women because this is the critical period during which fetal development occurs. Exposure to teratogens can happen through various means, such as medications, environmental toxins, infections, or certain substances like alcohol and nicotine. Understanding that teratogens have their most significant impact during pregnancy highlights the importance of careful consideration and screening for any potentially harmful substances in expectant mothers. This is why the correct answer identifies pregnant women as the primary group where teratogens are concerned, as they directly influence the developing fetus.