2 contracted vendor (Medical Marketing Service, Inc.). The AMA Masterﬁle, a database of all licensed US physicians, is the most comprehensive physician listing in the United States, and includes both AMA members and nonmembers. The sampling frame included all allopathic and osteopathic physicians self-described as an obstetrician/gynecologist, in oﬃce-based direct patient care. Excluded were physicians with any subspecialty board listing, physicians 70 years of age or older, resident physicians, and physicians practicing at federal government (ie, Veterans Aﬀairs, military) medical facilities. The study was approved by the Institutional Review Board of the University of Michigan Medical School, with a waiver of documentation of informed consent. Survey instrument The study team developed a one-page, 6-item survey instru- ment, accompanied by a one-page “Fact Sheet” regarding pertussis disease and the recently licensed Tdap vaccine. To verify eligibility, a screening item asked whether the respon- dent currently provides obstetric care. Survey items included current approach to administering inﬂuenza and measles- mumps-rubella (MMR) vaccines; likelihood of recommend- ing Tdap vaccine during pregnancy and during the postpar- tum hospital stay, if recommended by ACIP/ACOG; barriers to administering Tdap vaccine to obstetric patients; and per- ceived responsibility for promoting or administering Tdap vaccine to adults expected to come in close contact with young infants. The survey instrument and Fact Sheet were pilot tested with a convenience sample of obstetricians to ensure clarity and ease of administration. Reﬁnements were made based on pilot test feedback. Survey administration To meet the timeframe of the ACIP workgroup, only one mailing of the survey was ﬁelded, in August 2005. Survey packets contained a cover letter explaining the purpose of the study, the Fact Sheet and survey form, and a $5 cash incen- tive. Data analysis Initial univariate frequencies were generated for each vari- able. Chi-square analyses were performed to explore associa- tions between variables. A two-tailed α level of .05 was used as the threshold for statistical signiﬁcance. All analyses were conducted using SAS version 8.2 (SAS, Inc., Cary, NC). RESULTS Sample characteristics Of the 400 obstetricians in the study sample, 5 were ex- cluded because mailing materials were returned as undeliver- able. Surveys were returned by 212 respondents, for an over- all response rate of 54%. Of the 212 respondents, 29 were Infectious Diseases in Obstetrics and Gynecology ineligible because they do not provide obstetric care, leav- ing 183 surveys eligible for analysis. With regard to demo- graphic characteristics of this group, 79% are board-certiﬁed in obstetrics-gynecology; 40% are female; 43% are more than 50 years of age; and 47% work in a multispecialty practice site. Current approach to administering vaccines to obstetric patients Most respondents (87%) reported that they routinely ad- minister MMR vaccine to rubella nonimmune women im- mediately after delivery (postpartum hospital stay); 4% re- ported sometimes; and 9% reported rarely/never administer- ing MMR vaccine. In comparison, 61% reported routinely administering inﬂuenza vaccine to pregnant patients; 19% reported sometimes; and 20% reported rarely/never admin- istering inﬂuenza vaccine during pregnancy. Likelihood of recommending Tdap vaccine for obstetric patients Overall, 78% of respondents agree or strongly agree that they would likely recommend Tdap vaccine for women immedi- ately after delivery (in the postpartum hospital stay) if rec- ommended by ACIP/ACOG. A lower proportion (69%) of respondents agree or strongly agree that they would likely rec- ommend Tdap vaccine for women during pregnancy if rec- ommended by ACIP/ACOG. For both questions, only 9% of respondents strongly disagree that they would recommend Tdap vaccine. Respondents’ extent of agreement with these statements did not diﬀer by their current approach to ad- ministering inﬂuenza vaccine or MMR vaccine. Anticipated barriers to Tdap vaccination of obstetric patients Under the assumption of an ACIP/ACOG recommenda- tion for Tdap vaccination of postpartum and/or pregnant women, the most commonly expected major barrier to vac- cination was knowing the date of a patient’s most recent Td booster (74% of respondents). Nearly half of respondents (46%) felt patient reluctance or refusal would be a major bar- rier, while 19% reported that having other priorities during obstetric visits would be a barrier. With regard to an open- ended question about other barriers, 14% of respondents noted cost-related issues (eg, reimbursement, vaccine cost) as a potential barrier. In bivariate analyses, anticipated barriers cited by respon- dents were not associated with their likelihood of recom- mending Tdap vaccine to postpartum or pregnant women. Perspectives on Tdap vaccine for adults in close contact with infants Respondents were asked which physician group(s) should bear responsibility for promoting and administering Tdap vaccine to adults likely to come in close contact with infants