Frances Kelsey and Thalidomide

In 1960, FDA medical officer Frances Kelsey resisted approving thalidomide in the United States because the submitted evidence was inadequate. The drug had been sold elsewhere and was later linked to severe birth defects when taken during pregnancy.

Her persistence helped prevent the same scale of exposure in the United States, although investigational use meant exposure was not absent. The episode contributed to stronger drug regulation and highlighted the importance of independent review and reliable evidence.

If the application had been approved, more US pregnancies might have been exposed, but the number of resulting cases cannot be known. A different reviewer might still have delayed approval, and the disaster itself changed global awareness and regulation.

A strong safety system should not depend on one unusually persistent person. It needs reviewers protected from pressure, clear standards for evidence, and channels for acting on warning signs before harm becomes widespread.

If the application had been approved, more US pregnancies might have been exposed, but the number of resulting cases cannot be known.

When evidence is incomplete but the stakes are high, what pressure might make me treat uncertainty as permission to proceed?