Table 3.10

Drug classification for use of drugs during pregnancy

Class AControlled studies show no risk. Adequate well-controlled studies in pregnant women have failed to demonstrate risk to the foetus
Class BNo evidence of risk in humans. Either animal findings show risk, but human findings do not or, if no adequate human studies have been done, animal findings are negative
Class CRisk cannot be ruled out. Human studies are lacking, and animal studies are either positive for foetal risk or lacking as well. However, potential benefits may justify the potential risk
Class DPositive evidence of risk. Investigational or post-marketing data show risk to the foetus. Nevertheless, potential benefits may outweigh the potential risk
Class XContraindicated in pregnancy. Studies in animals or human, or investigational or
  • (FDA Classification of Drugs for Teratogenic Risk. Teratology society public affairs committee. Teratology 1994: 49:446-447).