What are teratogens?

• A. Neurotrophins
• B. Teratogens
• C. Teratology
• D. Teratogenicity

Answer: (B)

Teratogens are substances or factors that can cause birth defects or developmental problems in a fetus when exposure occurs during pregnancy. The risk depends on timing, dose, and the fetus’s genetics. The earliest, most vulnerable period is organ formation in the first trimester, where exposure can produce structural malformations; exposures later may affect growth or neurodevelopment rather than anatomy. Examples include certain medications (like thalidomide), alcohol, some infections, radiation, and environmental chemicals. The study of how these effects occur is called teratology, and the term teratogenicity refers to the capacity of a substance to cause birth defects. Neurotrophins, in contrast, are growth factors for neurons, not teratogens.