FDA Pregnancy Categories

The Food and Drug Administration (FDA) uses a system of pregnancy categories to classify the risk each drug to an unborn baby. Some drugs are safe to take during pregnancy, while others may result in fetal injury. Most medicines are assigned to one of these five categories and can be reassigned as new research emerges. To determine the safety of drugs you may take during pregnancy, it is very important to check the category of each one, including over-the-counter medications and natural supplements.

Drugs can also pass through the mother’s breast milk to the infant in small quantities. While many drugs will not cause harm to the infant, some are toxic and must be avoided.

Pregnancy categories include A, B, C, D, X, and N. Drugs that fall into these categories have been researched, and risk has been assessed as follows:

Category A

Sufficient and well-controlled studies have been conducted, and there is not evidence indicating a risk to the fetus during any trimester of pregnancy.

Category B

Animal reproduction studies have been conducted, which have not demonstrated risk to the fetus. There are no sufficient and well-controlled studies involving pregnant women to determine risk to human fetus.

Category C

Studies have been conducted on animals with results indicating possible adverse effect on the fetus. There are still no sufficient and well-controlled studies in humans, but the potential benefits of the drug may warrant its use in pregnant women.

Category D

There is positive evidence confirming human fetal risk based on data from investigational or marketing experience or studies in humans. However, the use of drugs in this category may still be warranted if potential benefits outweigh the risks.

Category X

Studies in animals or humans have indicated fetal abnormalities and/or there is positive evidence of human fetal risk based on collected data. The risks of Category X drugs clearly outweigh the benefits. Women who are or could become pregnant should not take drugs in this category.

Category N

This drug has not yet been classified by the FDA.