Which of the following is an example of a teratogen?

A teratogen is an agent or factor that causes malformation or developmental abnormalities in a fetus or embryo. The key characteristic of teratogens is their ability to cause these adverse effects during specific periods of development, especially during the first trimester of pregnancy, when the development of vital organs and systems occurs.

Rubella, which is caused by a virus, is a well-known teratogen. Exposure to rubella during pregnancy can lead to serious congenital defects, including heart defects, deafness, and eye abnormalities. The risk of these defects is particularly high if a mother contracts rubella during the first trimester, making it critical for pregnant women to be vaccinated against this virus prior to conception.

In contrast, Vitamin D, Folic Acid, and Iron supplements are not teratogens. In fact, Folic Acid is particularly important in preventing neural tube defects during pregnancy, and adequate Iron is necessary to prevent anemia, both of which support healthy fetal development. Therefore, Rubella stands out as an agent that can cause significant harm to fetal development, clearly aligning it with the definition of a teratogen.