The U.S. Food and Drug Administration (FDA) has proposed major revisions to prescription drug labeling in order to provide more accurate and helpful information on the effects of medications used during pregnancy and breastfeeding. As it stands, the current system used by the FDA classifies the reproductive safety of medications using five risk categories (A, B, C, D and X) based on data derived from human and animal studies. While widely used to make decisions regarding the use of medications during pregnancy, many have criticized this system of classification, indicating that this type of drug labeling is often not helpful and, even worse, may be misleading.

The newly designed 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.

The FDA has proposed to organize this information into three sections:

1) The first section, called the “Fetal Risk Summary,” would describe what is known about the effects of the drug on the fetus, and if there is a risk, whether this risk is based on information from animals or humans. The proposal calls for a risk conclusion based on the available data and provides a number of examples depending on the quality and quantity of that data. For example, one risk conclusion might be: “Human data indicate that (name of drug) increases the risk of cardiac abnormalities.” This would be followed by a summary of the most important data on the drug’s effects.

2) Another section, called “Clinical Considerations,” would include information about the effects of the use of the drug if it is taken before a woman knows she is pregnant. This section also would feature discussions about the risks of the disease to the mother and the baby, dosing information, and tell how to address complications.

3) The third section, under the heading “Data,” would describe in more detail the available data regarding use of the drug in humans and from animal studies that were used to develop the Fetal Risk Summary.

The breastfeeding section of the prescription drug labeling would provide information regarding the use of the drug while breastfeeding, including information on the amount of drug found in the breast milk and the risk of adverse events in the breastfed infant.

The public is encouraged to offer their feedback on this proposal. Comments may be submitted electronically to the FDA within 90 days via the Federal Documents Management System/eRulemaking portal at The FDA will carefully consider the comments in preparing a final rule.

Ruta Nonacs, MD PhD

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