The Advisory Committee on Immunization Practices (ACIP) has focused on maternal Tdap immunization as an important means to protect neonates from pertussis infections. There is little published data on provider and/or clinic characteristics as predictors of maternal Tdap uptake. This study examined differences in maternal Tdap coverage in women delivering at a single academic institution, but cared for prenatally in different clinical settings, in 2013, 2014, and 2015. Additionally, the accuracy and utilization of Vermont's immunization information system (IIS) was assessed. This was a retrospective, multiple time-point cross-sectional analysis of annual maternal Tdap coverage in women delivering at a single academic institution in the 3 years following a fundamental change in national maternal Tdap vaccination guidelines. Tdap administration was examined across different obstetric groups using chart review and data from the state's IIS. All obstetric care groups except the resident-staffed clinic significantly increased maternal Tdap coverage in 2014, compared to 2013 coverage, with no further increase in 2015. In contrast, there was no increase in maternal Tdap coverage in 2014 in the resident-staffed clinics, but then a statistically significant increase in 2015. Overall Tdap coverage in 2014 was 80.4%, with variation in Tdap coverage between clinics types. In the subset of women who were cared for by the University-based groups, there was significant variation in Tdap coverage between clinics, despite racial homogeneity, which persisted after adjustment for maternal age and insurance type. The state's IIS was found to be highly accurate, using individual chart review as the "gold standard." While we demonstrated high maternal Tdap coverage in women delivering at our institution, differences in clinic type and provider training appeared to impact immunization rates, as well as how quickly evolving national recommendations were adopted. Additionally, the fidelity of the state's IIS data was verified. Copyright © 2019 Elsevier Ltd. All rights reserved.