A Narrative Review of Progestin-Primed Ovarian Stimulation Protocols in Ovaries: Current Trends and Perspectives

Objective: This review aimed to provide an updated overview of progestin-primed ovarian stimulation (PPOS) outcomes across different patient groups, particularly in egg donation, fertility preservation, preimplantation genetic testing (PGT), and endometriosis. Mechanism: We performed a focused narrative review of the literature in the PubMed/MEDLINE databases, identifying randomized trials, cohort studies, systematic reviews, and meta-analyses comparing PPOS to gonadotropin-releasing hormone (GnRH) agonist and GnRH-antagonist protocols (search completed to April 2025). Selection emphasized high-quality evidence and recent comprehensive reviews across different patient groups. Findings in Brief: PPOS demonstrated efficacy across various clinical scenarios, including oocyte donation, fertility preservation, PGT, polycystic ovary syndrome (PCOS), low and high ovarian responses, and endometriosis. While overall neonatal safety is acceptable, some concerns persist regarding specific progestins, such as dydrogesterone. Conclusions: PPOS protocols represent valid, non-inferior alternatives to GnRH antagonists in various clinical populations when an oocyte- or embryo-freezing strategy is employed.