Pregnancy Categories

Every prescription drug goes through a pregnancy test of sorts during development and given an FDA rating. They are tested to see the drug in use can be passed on to the fetus through the placenta and cause adverse effects to the fetus. Testing is primarily done on animals to determine the adverse effects. Once those side effects have been established, human trials are performed to confirm and capture any additional side effects. The key is to minimize the risk to the fetus and mother as much as possible using these ratings or pregnancy categories.

Pregnancy Category A

This rating is provided to prescription drugs after adequate and well-controlled human studies have failed to demonstrate a risk to the fetus in the first trimester of pregnancy. There is also no evidence of risk of defects in the later trimesters.

Pregnancy Category B

This rating is provided once animal reproduction studies failed to demonstrate risk to the fetus and there are no adequate and well-controlled human studies to confirm the findings. The rating can also be given to prescription drugs that show adverse side effects in animal studies but no side effects in adequate and well-controlled human studies.

Pregnancy Category C

This rating is given to prescription drugs that show adverse side effects on the fetus in animal studies and there are no adequate and well-controlled human studies to confirm the findings. But, the benefit of the drug to pregnant mothers outweighs the risks to the fetuses.

Pregnancy Category D 

This rating is given to prescription drugs that show adverse effects to fetuses based on investigational experience, marketing experience or human studies. The prescription drug is still approved for use since the benefit of the drug to pregnant mothers outweighs the risks.

Pregnancy Category X

The rating is given if studies in animals and humans show adverse fetal abnormalities or there is positive evidence of fetal risk based on investigational and marketing experience. The risk involved in potential use outweighs the benefit. It is safe to say that a prescription drug marked category X should never be used by pregnant women.

Pregnancy Category N

This rating is provided when the FDA has not classified the drug. Basically it means, the FDA does not have enough information on the drug.

If you are concerned about pregnancy ratings, the information should be provided by your doctor or in the medical insert. Keep in mind that the above ratings are for the United States (US) only and each country has its own rating system. Are these ratings useful?