Comparative Analysis of Progestin-Primed and Luteal-Phase Ovarian Stimulation Protocols in Patients With Diminished Ovarian Reserve Undergoing In Vitro Fertilization–Embryo Transfer

Background: Patients with diminished ovarian reserve (DOR) face challenges such as inadequate follicular recruitment and decreased oocyte quality when subjected to in vitro fertilization and embryo transfer (IVF-ET) treatment. Methods: This retrospective self-controlled study included 130 patients with DOR who underwent IVF-ET using either the progestin-primed ovarian stimulation (PPOS) or luteal-phase ovarian stimulation (LPOS) protocol. In the PPOS protocol, ovarian stimulation was initiated in the early follicular phase with medroxyprogesterone acetate (MPA) combined with gonadotropins. In the LPOS protocol, ovarian stimulation began in the luteal phase with letrozole and gonadotropins, followed by dydrogesterone. Final oocyte triggering, retrieval, and embryo culture were performed using standardized procedures. The primary outcomes included gonadotropin consumption, oocyte maturation and fertilization rates, as well as pregnancy-related outcomes. Results: Compared to the LPOS group, the PPOS protocol was associated with a significantly shorter duration of gonadotropin stimulation and a lower total gonadotropin dose (p < 0.05). The LPOS group did not have significantly higher metaphase II (MII) oocyte and normal fertilization rates (p > 0.05). The abnormal fertilization rate was numerically lower in the LPOS group, but the difference was not statistically significant. Multivariate logistic regression analysis revealed that the LPOS protocol remained independently associated with a higher MII oocyte rate (adjusted odds ratio [aOR]: 1.42, 95% confidence interval [CI]: 1.07–1.91, p = 0.017), even after adjusting for age, body mass index (BMI), and antral follicle count (AFC). No significant association was observed between stimulation protocol and clinical pregnancy after adjustment. Conclusion: Both PPOS and LPOS protocols effectively prevent premature luteinizing hormone (LH) surges and support the development of viable embryos in patients with DOR. Multivariate analysis further confirmed LPOS as an independent predictor of improved oocyte maturity, suggesting its potential utility in individualized stimulation strategies for this patient population.