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New Study Estimates That Some Pregnant Women Are Prescribed Drugs Which May Be Considered Unsafe During Pregnancy

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Press Release Date: September 8, 2004

Nearly half of pregnant women who had received medications other than vitamins may be taking drugs that the Food and Drug Administration (FDA) classifies as having no human evidence of safety for use during pregnancy or that evidence has shown can harm a developing fetus, according to a new study funded by HHS' Agency for Healthcare Research and Quality (AHRQ). The article is published in the August 2004 issue of the American Journal of Obstetrics and Gynecology.

The study, the largest to date to examine the prescription drug use of women during pregnancy, was conducted by researchers at AHRQ's HMO Research Network Center for Education and Research on Therapeutics (CERTs). The CERTs program is a national initiative to increase the awareness of the benefits and risks of new, existing, or combined uses of therapeutics and devices.

Researchers reviewed data from eight health maintenance organizations in diverse geographic areas. They evaluated prescription drug use by 152,531 women who delivered an infant in a hospital from January 1, 1996, through December 31, 2000, based on the FDA's risk classification system of drugs during pregnancy. The study did not review the use of over-the-counter medications or drugs prescribed in hospitals.

"The findings of this research clearly show clinicians need state-of-the-science information about which medications are safe and appropriate for their patients during pregnancy," said AHRQ Director Carolyn M. Clancy, M.D. "Health information technology is an important key to getting that information into the hands of clinicians quickly so they can work with their patients to make informed health care decisions."

Researchers found that 64 percent of women were dispensed a medication other than a vitamin or mineral supplement within the 270 days prior to delivery. Of those, nearly 40 percent of women were dispensed a drug for which human safety has not been established (Category C on the FDA's list). Nearly 5 percent were dispensed drugs from Category D, which the FDA classifies as having positive evidence of fetal risk, but benefits of use may be acceptable despite the risk. An additional 5 percent of women were dispensed a drug from Category X, for which the evidence has found definite fetal risks based on human or animal studies or based on human experience, and risk of using the drugs clearly outweighs any possible benefit.

The other approximately 50 percent of prescriptions were classified as Category A (risk to the fetus is remote) and Category B (animal studies do not show fetal risk and there are no controlled studies in women; or animal studies show risk, but controlled studies in women fail to show risk).

"The limitations of the letter category system and its application are well established, as is the public health need for better information," said FDA Deputy Director of the Office of New Drugs Sandra L. Kweder, M.D. "FDA is revising the system to provide a more informative tool for doctors and patients."

Researchers conclude that routine medication audits and physician education as well as new technologies, such as computerized prescription systems with clinical supports, may have the potential to reduce inappropriate prescribing for pregnant women.

Editor's Note: This is the second study supported by AHRQ on the safety of medications dispensed to pregnant women. The earlier study, "Prescriptions for contraindicated category X drugs in pregnancy among women enrolled in TennCare," by William O. Cooper, Gerald B. Hickson and Wayne A. Ray, was published in the March 2004 issue of Pediatric and Perinatal Epidemiology.

For more information, please contact AHRQ Public Affairs: (301) 427-1863 or (301) 427-1855.


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