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Prescription Drugs in Pregnancy

Understanding the FDA's Category Ranking System


Updated June 18, 2014

Pregnancy Medication

Talk to your doctor or pharmacist if you are concerned about the safety of your medications during pregnancy.

Photo © Stock.xchng user Dimshik

Taking drugs while pregnant can be scary, but sometimes it is necessary. If you have to take medication while you're pregnant, you might hear talk of different lettered categories. Few medications are definitively proven to be 100% safe during pregnancy, but in many cases, physicians prescribe them in cases where a medical condition poses significant risk to the mother or baby's health if left untreated.

Prescription drugs are divided into categories based on what researchers know about safety of taking that particular drug while pregnant.

Some medications do increase the risk of miscarriage and birth defects, but many others are probably safe. If you have to take a Category D or X medication, you face increased risk for miscarriage, and your doctor will probably advise you to use contraception.

Here is a quick rundown of how to read the category ranking system:

Category A

Drugs labeled as category A have been thoroughly studied in pregnant women and no research has shown an increased risk of pregnancy loss or birth defects. Only a few drugs fall into this category.

Category B

Category B medications may have been studied in animals with no evidence of harm, but studies done on pregnant women may be lacking. Or, animal studies may have found adverse effects, but studies on pregnant women found no such risks.

Category C

Researchers may have found adverse effects in animals, but there are no adequate studies on pregnant women using the drug. Category C may also mean that there are no animal studies or studies on pregnant women.

Category D

Category D medications have been demonstrated to cause adverse effects in pregnant women, but the benefits may outweigh the risks in some cases. This might be true in cases where if a woman does not take the category D medication, her life or her baby's life might be in danger.

Category X

Category X is the strongest safety warning and indicates that the drug is completely inappropriate for use by pregnant women.


Meadows, Michelle. "Pregnancy and the Drug Dilemma." FDA Consumer May 2001. Accessed 29 Oct 2007.

  1. About.com
  2. Health
  3. Miscarriage / Pregnancy Loss
  4. Risk Factors
  5. Pregnancy Medications
  6. Safety Categories for Prescription Pregnancy Drugs

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