Safety of Drugs in Pregnancy
Pregnancy Safety Guide
A Guide to Drug Safety in Pregnancy - An U.S. FDA categorisation of risk of drug use in pregnancy.
As part of our continual efforts to improve the quality and comprehensiveness of drug information in MIMS, we have included a simple guide to the safety of drugs in pregnancy. No representations on the safety of a drug in pregnancy can be made for products without a risk factor grading. Most topical preparations do not have a pregnancy category as systemic absorption is generally considered to be minimal unless use is extensive, intensive or prolonged.
Definitions of Risk Factors
These definitions are those used by the United States Food and Drug Administration (FDA). These categories do not imply an increasing progression of risk from A to X. Drugs are categorised based on the risk of reproductive and developmental adverse effects and on risk versus benefit considerations. Drugs in categories D, X, and in some cases C, may pose similar risk, but may be categorised differently on the basis of different risk versus benefit considerations.
For more information, please visit
Category A: Controlled studies in women fail to demonstrate a risk to the foetus in the 1st trimester (and there is no evidence of a risk in later trimesters), and the possibility of foetal harm remains remote.
Category B: Either animal-reproduction studies have not demonstrated a foetal risk but there are no controlled studies in pregnant women or animal-reproduction studies have shown an adverse effect (other than a decrease in fertility) that was not confirmed in controlled studies in women in the 1st trimester (and there is no evidence of a risk in later trimesters).
Category C: Either studies in animals have revealed adverse effects on the foetus (teratogenic or embryocidal or other) and there are no controlled studies in women or studies in women and animals are not available. Drugs should be given only if the potential benefit justifies the potential risk to the foetus.
Category D: There is positive evidence of human foetal risk, but the benefits from use in pregnant women may be acceptable despite the risk (e.g., if the drug is needed in a life-threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective).
Category X: Studies in animals or human beings have demonstrated foetal abnormalities or there is evidence of foetal risk based on human experience or both, and the risk of the use of the drug in pregnant women clearly outweighs any possible benefit. The drug is contraindicated in women who are or may become pregnant.
A group of drugs with pregnancy related alerts from expert committees or regulatory agencies, but not assigned with any US FDA Pregnancy Category, have been classified as Category Z.
Category Z: There are studies, recommendations or alerts from respective expert committees and/or regulatory agencies for healthcare professionals regarding use of this drug during pregnancy. Read the accompanying text in the generic monographs for more information.