The FDA requires that all drugs be classified according to their known ability to cause birth defects or other risks during pregnancy. To that end, they devised a five-letter chart: A, B, C, D, and X, This classification system is especially pertinent in anti-cancer treatments, since they can pose their own health hazards.
The FDA classifications are:
- Category A. Adequate, well-controlled studies in pregnant women have not shown an increased risk of fetal abnormalities
- Category B: Animal studies have revealed no evidence of harm to the fetus, however, there are no adequate and well-controlled studies in pregnant women OR Animal studies have shown an adverse effect, but adequate and well-controlled studies in pregnant women have failed to demonstrate a risk to the fetus.
- Category C: Animal studies have shown an adverse effect and there are no adequate and well-controlled studies in pregnant women OR No animal studies have been conducted and there are no adequate and well-controlled studies in pregnant women.
- Category D: Studies, adequate well-controlled or observational, in pregnant women have demonstrated a risk to the fetus. However, the benefits of therapy may outweigh the potential risk.
- Category X: Studies, adequate well-controlled or observational, in animals or pregnant women have demonstrated positive evidence of fetal abnormalities. The use of the product is contraindicated in women who are or may become pregnant.
Note: The U.S. Food and Drug Administration (FDA) is proposing major revisions to prescription drug labeling to provide more complete information about the effects of medicines used during pregnancy and breast-feeding. The proposal would eliminate the current pregnancy categories A, B, C, D, and X. The “Labor and Delivery” subsection would be eliminated because information on labor and delivery would be included in the “Pregnancy” subsection. Complete details here
