Background: In vitro fertilization (IVF) outcomes are shaped by individual factors, laboratory conditions, and clinician performance; however, while embryologists and laboratory conditions are well studied, clinician-related variables remain less explored.

Objective: This study aims to evaluate whether pregnancy outcomes vary in IVF cycles managed by different clinicians.

Materials and Methods: In this cohort study, data of 3017 women who underwent intracytoplasmic sperm injection at the IVF Center of Kadıköy Florence Nightingale hospital, İstanbul, Türkiye from January 2013-December 2020 were extracted from their medical records and retrospectively reviewed. Clinical pregnancy rates were compared between clinicians.

Results: Clinical pregnancy rates differed significantly between clinicians, ranging from 13.6–56.0% (p = 0.023). The overall pregnancy rate was 29.9%. In the multivariate analysis, even after adjusting for maternal age, body mass index, duration of infertility, and anti-Müllerian hormone levels, the clinician variable retained its significance as an independent predictor (adjusted odds ratios: 0.45–2.12, p = 0.018).

Conclusion: Our study shows that clinician-related factors independently shape IVF success. Clinical expertise, judgment, and surgical skills affect outcomes throughout the IVF cycle, not only at embryo transfer. Improving laboratory conditions alone is insufficient; clinician training, performance standardization, and ongoing professional development are also essential. Thus, clinician performance should be integrated into quality assurance and further evaluated in prospective multicenter studies.