FDA reviewer Frances Kelsey refused to approve thalidomide in the early 1960s due to insufficient safety information.

“there was a reviewer at the fledgling FDA who refused to approve a drug called thalidomide so this is now 30 years after yeah yeah this is early 60s yeah which was being widely dispensed in Europe to help pregnant women who were having trouble sleeping sickness morning sickness and she basically held firm they basically saying that she didn't have enough information on the drug and of course it turned out she was correct America dodged a bullet because that drug was associated with children who were born with flipper like arms so it was associated with horrible birth defects”