FDA Pregnancy Categories

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FDA Pregnancy Categories

The rational use of any medication requires a risk vs benefit assessment. Among the myriad of risk factors which complicate this assessment, pregnancy is one of the most perplexing.

The FDA has established 5 categories to indicate the potential of a systemically absorbed drug for causing birth defects. The key differentiation among the categories rests upon the degree (reliability) of documentation and the risk vs benefit ratio. Pregnancy Category X is particularly notable in that if any data exists that may implicate a drug as a teratogen and the risk vs benefit ratio does not support use of the drug, the drug is contraindicated during pregnancy. These categories are summarized below:

FDA Pregnancy Categories
Pregnancy Category	Definition
A	Controlled studies show no risk. Adequate, well-controlled studies in pregnant women have failed to demonstrate risk to the fetus.
B	No 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.
C	Risk cannot be ruled out. Human studies are lacking, and animal studies are either positive for fetal risk or lacking. However, potential benefits may justify the potential risks.
D	Positive evidence of risk. Investigational or postmarketing data show risk to the fetus. Nevertheless, potential benefits may outweigh the potential risks. If needed in a life-threatening situation or a serious disease, the drug may be acceptable if safer drugs cannot be used or are ineffective.
X	Contraindicated in pregnancy. Studies in animals or human, or investigational or post-marketing reports have shown fetal risk which clearly outweighs any possible benefit to the patients.