The Food and Drug Administration (FDA) has defined categories of drugs for use in pregnant women relative to risk of teratogenicity. In general, drugs should not be administered to a pregnant woman except when the benefits outweigh the risks.
Parameters:
(1) animal studies for teratogenicity
(2) data on human exposures during pregnancy
(3) benefit to risk assessment
Animal Studies
Human Studies
Benefit and Risk
FDA Category
negative
negative
benefit > risk
A
negative
not available/done
benefit > risk
B
positive
negative
benefits > risk
B
positive
not available/done
benefits > risk
C
not done
not available/done
benefits > risk
C
negative
positive
benefits > risk
D
positive
positive
benefits > risk
D
positive
positive
benefits < risk
X
where:
• Drugs classed as "X" are contraindicated in pregnancy.
When animal and human studies are looked at, there are 9 permutations based on each being negative, not done or positive.
Animal Study
Human Data
Category
negative
negative
A
negative
not done
B
negative
positive
D
not done
negative
presume B
not done
not done
C
not done
positive
presume D
positive
negative
B
positive
not done
C
positive
positive
D or X
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