The correlation between obstetrics and gynecology residency program size and type with certifying examination passage rates is not previously reported. Our objective was to evaluate the relationship between residency program size and type with American Board of Obstetrics and Gynecology (ABOG) certifying examination (CE) pass rates.

This is a cross-sectional study of ABOG specialty CE passage rates from 2020 to 2022. The CE passage rates were obtained from the ABOG website and stratified by program size (small 3–4, medium 5–7, large >8 residents per class) and type (community-based; community-based, university-affiliated; and university-based). Military-based programs were excluded, as were programs of unknown size. Passage rates were compared among groups using chi-squared test.

During the study period, 3,766 candidates sat for the CE. Small programs accounted for 730 candidates (19.4%), 1,805 (47.9%) candidates from medium programs, and 1,231 candidates (32.7%) from large programs. Passage rates were higher among medium and large programs versus small programs (small [604/730; 82.7%], medium [1,656/1,805, 91.7%], and large [1,149/1,231; 93.3%]; P<.001). Passage rates among community-based candidates (299/347; 86.2% pass rate) and community-based university-affiliated candidates (962/1,100; 87.5% pass rate) were lower versus university-based candidates (2,148/2,319; 92.6% pass rate; P<.0001).

During the study period, university-based programs and medium or large programs had higher CE passage rates. There are a number of limiting factors to the interpretation of the results such as academic differences upon entry to residency, resources available at each program, and amount of dedicated study time. A causal effect of program size and type cannot be assumed.