This is a very nice article published by the College of Psychiatric and Neurologic Pharmacists discussing the limitations of the current FDA pregnancy category labeling system.
“The main criticism of the category system is that it oversimplifies what is in fact a very complicated, individualized clinical decision. The risk of untreated illness and/or possible benefits of the medication are mentioned briefly as considerations, but are not elaborated on and are often overshadowed by the perception of risk of the medication.”
Other shortcomings noted by the author:
- The current labeling system does not reflect the timing of exposure and the effects of drug exposure at various times of the pregnancy. (For example, exposure to lithium during the first trimester carries different risks than exposure to lithium during the third trimester.)
- It is often assumed that medications within the same category carry the same risk. (Lithium and valproic acid are both in category D: however, lithium carries a 0.1% risk of a cardiovascular malformation called Ebstein’s anomaly, whereas valproic acid carries a risk of major malformations of between 7% and 10%.)
- The FDA does not update labeling based on new findings. (Paroxetine was changed to category D; however, when new data suggested that there was no increase in risk of cardiovascular malformation, the labeling remained the same.)
- Finally, there is no information on the use of medications during lactation.
In 2008, the FDA announced that it would be revising the category labeling; the new system would abolish the letter categories and would include more comprehensive information discussing the potential risks and benefits to the mother and the fetus, and how these risks may change during the course of pregnancy. Here is an example of the proposed format.
At the annual meeting of the Teratology Society in June, it was announced that these new labels are in their final stages of editing and are expected t be released within the next year.
Ruta Nonacs, MD PhD
Wood W. FDA Pregnancy Categories: Help or Hindrance? Ment Health Clin. 2013; 3(2):100.
Pregnancy and Lactation Labeling (FDA website)