It is not the first time Public Citizen has taken aim at the labeling of drugs for women. In an April 2005 letter to the FDA, Public Citizen criticized the lack of information on drug labels, calling information for nursing mothers "rarely helpful."
Wolfe said the ideal approach would have been to apply the existing rating system used with regard to pregnancy -- with a few tweaks -- to lactation as well.
The system FDA is proposing, he said, could provide breast-feeding mothers with more information but may hurt efforts to keep pregnant women informed.
"For lactation, since there weren't any categories before, it may be a step forward," he said. "But it may be a step backward for pregnancy."
The proposed guidelines may be complicated by the fact that, for many drugs, there is little research available on their potential effect on pregnant and nursing women or their children. Since testing drugs on pregnant and nursing women poses huge ethical questions, most of the data available is from animal studies, research that goes only so far when it comes to determining possible effects on humans.
The form in which the new recommendations will go into effect will be determined largely over the next 90 days, during which the FDA will accept comments from medical professionals and the public. The agency said it expects the rule to go into effect "no earlier than June 30, 2010."
But for some, the changes cannot come soon enough.
"As a pediatrician and mother, it is frustrating to make medication decisions with the current risk categories that are vague at best," said Dr. Tasneem Bhatia of the Atlanta Center for Holistic and Integrative Medicine.
"Women today are already concerned with the risks of many environmental toxins -- vaccines, antibiotics, contaminated food, et cetera. It would be helpful to take medications out of this list."
Kate Barrett contributed to this report.