FDA Nixes Use of Pregnancy Categories for Drugs

Why We're No Longer Confused by Pregancy Categories


If you or someone you love has ever been pregnant, then you may be familiar with the 5 pregnancy categories, A, B, C, D and X. Drug manufacturers have long used these FDA-created categories to classify risk in medications taken during pregnancy. After years of study, the FDA has finally gotten rid of these categories which have confused patients and prescribers alike and replaced them with narrative guidelines which aim to explain "real-world" risk in more accessible terms.

Pregnancy Categories Explained

Way back in 1979, the FDA required that drugs that are systemically absorbed and known to potentially harm the fetus must be labeled with pregnancy categories.

  • Category A: Controlled studies in pregnant women fail to suggest risk of adverse effects to the fetus (think folic acid and thyroxine).
  • Category B: Either animal reproductive studies suggest no risk of adverse effects to the fetus, or animal studies have shown risk of adverse effects; however, these risks weren't confirmed in studies of pregnant woman (think acetaminophen, penicillins, and cephalosporins).
  • Category C: Either no controlled studies have been reported on, or studies in animals have shown increased risk of adverse effects; however, no studies have been done in pregnant women. The drug might be given if potential benefit justifies potential risk (think antiviral medications like acyclovir or zidovudine).
  • Category D: Evidence of human fetal risk exists; however, such risk may be acceptable especially when no other treatment exists, or a condition is life-threatening (think the antibiotic tetracycline and the seizure medication phenytoin).
  • Category X: The drug is absolutely contraindicated during pregnancy (think isotretinoin, statins, and the blood thinner warfarin).

    According to the feds, here's why the pregnancy categories were dumped:

    Through experience and stakeholder feedback, FDA learned that the pregnancy categories were confusing and did not accurately and consistently communicate differences in degrees of fetal risk. In addition, FDA learned that the pregnancy categories were heavily relied upon by clinicians but were often misinterpreted and misused in that prescribing decisions were being made based on the pregnancy category, rather than an understanding of the underlying information that informed the assignment of the pregnancy category. FDA believes that a narrative structure for pregnancy labeling, rather than a category system, is best able to capture and convey the potential risks of drug exposure based on animal or human data, or both. FDA has determined that retaining the pregnancy categories is inconsistent with the need to accurately and consistently communicate differences in degrees of fetal risk.

    In other words, because many physicians don't understand how to use them, and people griped about them, too, the feds got rid of the pregnancy categories and replaced them with a "narrative structure." In a December 2014 press release, the FDA also deems these categories too simplistic, and these categories were being improperly interpreted by prescribers as a "grading system."

    What 'Narrative Structure' Did the FDA Replace Pregnancy Categories With?

    From now on, drugs and biological products must be labeled with the following 3 subsections titled Pregnancy, Lactation and Females and Males of Reproductive Potential.

    • Pregnancy. This subsection will describe medication dosing, a drug's risk of adverse effects to the fetus and whether a registry exists that documents these adverse effects.
    • Lactation. This section will describe the amount of drug or biological product that makes it into the breast milk and the resulting risk of adverse effects to the breastfed child.
    • Females and Males of Reproductive Potential. This section expatiates how the drug affects pregnancy testing, infertility and contraception. (It's interesting that the FDA refers to men and women as "males" and "females." According to the AMA Manual of Style and other texts on medical writing, the words male and female should be used only as adjectives.)

      By using this new narrative structure, the FDA hopes to further standardize labeling practices and mandates the inclusion of new information such as the existence of a registry that documents adverse effects. With more consistency and more robust explanations, the feds anticipate that people will better understand the drugs.

      The FDA projects the one-time cost to implement such changes at $60.1 million, and the projected annual costs at $18.2 million. These costs might trickle down in some small way to you, the health care consumer. However, to borrow a conceptual term from the soon-to-be-defunct pregnancy categories, the FDA hopes that such costs will be justified by physicians and other health care providers' better understanding of how to use these drugs. Ostensibly, by physicians understanding how to better prescribe such drugs, clinical outcomes for you will be improved. However, such benefit will take time to shake out, so for now we just have to wait and see what happens.

      Selected Sources

      "Content and Format of Labeling for Human Prescription Drug and Biological Products; Requirements for Pregnancy and Lactation Labeling" from the Federal Register and accessed on 12/4/2014 http://1.usa.gov/1ylrdA5

      Demian E, Rizk M. Chapter 16. Preconception Care. In: South-Paul JE, Matheny SC, Lewis EL. eds. CURRENT Diagnosis & Treatment in Family Medicine, 3e. New York, NY: McGraw-Hill; 2011. Accessed December 04, 2014.