The drug thalidomide was used during the early 1960s as a sedative during pregnancy. It was withdrawn in 1962 when it was shown that taking the drug during days 30 to 70 of gestation resulted in gross limb deformity - phocomelia. This experience has demonstrated that animal models and tests on adults are insufficient to guarantee the absence of teratogenic effects.
However, one should be circumspect about attributing single cases of deformity to a drug taken during pregnancy.
Of 1000 births there will be:
- 5 deaths from major malformations
- 10 babies with clinically significant abnormalities
Only very rarely may these deformities be attributed to drugs taken during the pregnancy.