Which agent was linked to a large increase in newborns with amelia or phocomelia in West Germany around 1960, along with other congenital anomalies?

• A. Diethylstilbestrol
• B. Thalidomide
• C. Ethanol
• D. Antiepileptic drugs

Answer: (B)

Thalidomide was the drug responsible. It was prescribed in the late 1950s as a sedative and antiemetic for pregnant women, and in West Germany around 1960 a large number of newborns showed limb defects—amelia (missing limbs) and phocomelia (limbs that are severely shortened or flipper-like)—often with other congenital anomalies. This pattern pointed to exposure during a critical early period of development, when limbs are forming, and investigations traced the defects to thalidomide use in pregnancy. The drug’s effects are thought to involve disruption of blood vessel formation in the developing limbs (anti-angiogenic activity), which during a narrow window of gestation leads to those specific limb defects. The tragedy led to how drugs are tested and regulated for safety in pregnancy. While other agents can cause congenital problems, the distinctive cluster of limb malformations tied to thalidomide is the defining association here.