Thalidomide was used in the 1960s for pregnant women. Why is it controversial?

• A. Caused children to be born with deformed limbs
• B. Cured pregnancy-related morning sickness
• C. Was safe and effective in all cases
• D. Had no side effects

Answer: (A)

The key idea here is safety in pregnancy and the serious harm a drug can cause to a developing fetus. Thalidomide was marketed as a harmless treatment for morning sickness, but it turned out to be teratogenic, meaning it could disrupt fetal development. The most devastating consequence was birth defects, especially limb abnormalities, which affected thousands of babies. This clash between a supposed remedy and such profound harm sparked deep public and medical concern and led to major changes in how drugs are tested and regulated, particularly for use during pregnancy. That is why identifying the link to birth defects is the best explanation for why thalidomide is controversial.

Other descriptions—saying it cured morning sickness, or that it was safe and effective in all cases, or that it had no side effects—don’t fit the historical reality. They ignore the documented, severe fetal harm and the broader safety and ethical concerns that drove the controversial reaction.