This single-centre retrospective cohort study aimed to investigate whether a clomiphene citrate (CC) priming protocol could increase ovarian sensitivity in poor ovarian responders. It included 294 patients (374 ovarian stimulation cycles). Of these, 193 cycles were treated by a CC priming antagonist protocol (study group) and 181 by the classical flexible gonadotropin-releasing hormone antagonist protocol (control group). Stimulation data and laboratory and clinical outcomes were compared between the groups. The results showed that in the study group, total gonadotropin dosage and dosage per follicle were considerably lower, the follicle-to-oocyte index was significantly higher, and the gonadotropin duration was shorter. After adjusting for potential confounders, multivariate regression analysis showed that cumulative ongoing pregnancy remained comparable between the groups (adjusted odds ratio: 0.761, 95% confidence interval: 0.300-1.933, p = 0.566). Age, body mass index, gonadotropin dosage per follicle, and the follicle-to-oocyte index were negatively associated with the reproductive outcomes. The result of the sensitivity analysis showed that patients in the study group were administered less gonadotropin at a lower gonadotropin dosage per follicle and for a shorter duration. In conclusion, the CC priming antagonist protocol offered a convenient and patient-friendly way to increase ovarian sensitivity during ovarian stimulation in poor ovarian responders.
Keywords: Antagonist; clomiphene citrate; ovarian sensitivity; in vitro fertilization; ovarian stimulation; poor ovarian response.