 Outside of the US, the drug thalidomide was marketed for the relief of general nausea and morning sickness but caused birth defects and even the death of thousands of babies when taken during pregnancy.American mothers were largely unaffected as Dr. Frances Oldham Kelsey of the FDA refused to authorize the medication for market, the 1962 Kefauver-Harris Amendment to the FD&C Act was passed, which represented a "revolution" in FDA regulatory authority.The most important change was the requirement that all new drug applications demonstrate "substantial evidence" of the drug's efficacy for a marketed indication, in addition to the existing requirement for pre-marketing demonstration of safety.