CLINICAL RESEARCH STUDY Prescription of teratogenic medications in United States ambulatory practices Eleanor Bimla Schwarz, MD, MS, a Judith Maselli, MSPH, b Mary Norton, MD, c Ralph Gonzales, MD, MSPH b a Center for Research on Health Care, University of Pittsburgh, Pittsburgh, Pa; b Department of Medicine, Division of General Internal Medicine; and c Department of Obstetrics, Gynecology, and Reproductive Science, University of California, San Francisco, Calif. ABSTRACT PURPOSE: The purpose of this study was to identify the potentially teratogenic medications most frequently prescribed to women of childbearing age and the specialty of physicians who provide ambulatory care to women who use such medications. In addition, we evaluated rates of contraceptive counseling to explore awareness of the risks associated with teratogenic medication use. SUBJECTS AND METHODS: The prescription of teratogenic medications and provision of contraceptive counseling on 12 681 visits made by nonpregnant women, 14 to 44 years of age, to 1880 physicians in US ambulatory practice (National Ambulatory Medical Care Survey) between 1998 and 2000 was analyzed. RESULTS: Use of a potentially teratogenic, class D or X, medication by a woman of childbearing age is documented on 1 of every 13 visits made to US ambulatory practices. These include anxiolytics (4.1 million annual prescriptions), anticonvulsant medications (1.4 million annual prescriptions), antibiotics like doxy- cycline (1.4 million annual prescriptions), and statins (0.8 million annual prescriptions). Isotretinoin accounts for less than 5% of potentially teratogenic prescriptions (0.5 million annual prescriptions). Internists and family/general practitioners provide ambulatory care to 45% of women prescribed potentially teratogenic medications, psychiatrists provide ambulatory care to 20% of women prescribed potentially teratogenic medications, and dermatologists provide ambulatory care to 20% of women prescribed potentially terato- genic medications. Contraceptive counseling was provided on less than 20% of visits that documented use of a potential teratogen by a woman of childbearing age. Women using low-risk (class A or B) drugs received contraceptive counseling as frequently as women using potential teratogens (P = .24). CONCLUSION: Potentially teratogenic medications are prescribed to millions of women of childbearing age each year. Physician awareness of the teratogenic risk associated with class D or X medications seems low. © 2005 Elsevier Inc. All rights reserved. KEYWORDS: Prescription drug; Teratogens; Birth defects; Contraception; National Ambulatory Medical Care Survey (NAMCS) Each year in the United States, 150 000 infants (1%-3% of all births) are born with some form of physical or mental birth defect. 1 The exact cause of these defects is generally unknown, although teratogenic exposures are known to underlie some birth defects. Known teratogens include environmental expo- sures such as radiation, dietary exposures such as alcohol, and medications such as thalidomide and isotretinoin. As for some conditions, equally effective medications that are not terato- genic do not exist, and use of potentially teratogenic medica- tions is sometimes necessary in treating women of reproduc- tive age. Unfortunately, it has been estimated that approximately 6% of US pregnancies are exposed to poten- tially teratogenic class D or X medications. 2 Funding for this analysis, interpretation of the relevant data, and prep- aration of this article was provided by a Department of Veterans Affairs Women Veterans’ Health Fellowship. Requests for reprints should be addressed to Eleanor Bimla Schwarz, MD, MS, Center for Research on Health Care, University of Pittsburgh, 230 McKee Place, Suite 600, Pittsburgh, PA 15213. E-mail address: schwarzeb@upmc.edu 0002-9343/$ -see front matter © 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.amjmed.2005.02.029 The American Journal of Medicine (2005) 118, 1240-1249