May 28 (Bloomberg) -- Prescription drugs would carry new warnings about risks for women who are pregnant or breastfeeding under a proposal from U.S. regulators.

The changes would make prescribing information more consistent so doctors can decide which medicines are best for women of childbearing age, said Food and Drug Administrator Commissioner Andrew von Eschenbach in a phone briefing today.

About 6 million women become pregnant in the U.S. each year, including about 3 million who aren't planning to have a child, and each uses an average of three to five prescription drugs, officials said. The proposal would eliminate the current system, instituted in 1979, in which every product is labeled with one of five letters denoting the level of risk.

``This system has led to an inaccurate and overly simplified view of prescribing during pregnancy and its attendant risks,'' said Sandra Kweder, a senior drug regulator, during the briefing for reporters. ``Most labels are sorely out of date.''

The proposed rule would require that the prescribing information for every drug include a summary of the risks to a fetus based on data gathered in human and animal experiments and descriptions of the research on which it is based. The literature would also present dangers to women taking the drug before they learn they are pregnant, along with the risks of not taking a drug for chronic conditions, such as high blood pressure and asthma.

For women who are breastfeeding, the information would include the amount of the drug found in mother's milk and potential effects on the child.

Public Comment

If approved, the proposal would take effect immediately for new drugs and over a period of years for previously approved medicines. Members of the public can submit comments to the agency for the next 90 days. The timing of final action will depend on whether more changes are needed, Kweder said.

``We think it's high time to get this thing published,'' she said.

The FDA has been reviewing ways to communicate information on reproductive and developmental risks of drugs since 1997, according to the agency. Kweder said the process, involving expert panels, focus groups and numerous labeling approaches, was the most difficult she has worked on as a regulator.

``Finding a way to require scarce information to be pulled together and then explained in a way that is balanced, scientific and conveys information practically is extraordinarily challenging,'' Kweder said. ``These are people about whom the most information is desired and the least information is available.''

To contact the reporters on this story: Avram Goldstein in Washington at agoldstein1@bloomberg.net; Catherine Larkin in Washington at clarkin4@bloomberg.net.

Last Updated: May 28, 2008 16:19 EDT