Effect of estradiol decrease from the hCG trigger day to the embryo transfer day on clinical outcomes in diminished ovarian reserve patients undergoing GnRH-antagonist protocol: a retrospective study

Diminished ovarian reserve (DOR) represents a critical clinical challenge in assisted reproductive technology (ART), and the gonadotropin-releasing hormone (GnRH) antagonist protocol has become a commonly used regimen for DOR treatment. Although estradiol (E₂) is well established as a pivotal regulator of embryo implantation, the prognostic impact of E₂ decrease from the human chorionic gonadotropin (hCG) trigger day to the embryo transfer day on ART outcomes remains unclear in DOR patients undergoing a GnRH-antagonist protocol. This retrospective study included 570 eligible in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles of DOR patients classified as POSEIDON Groups 3 and 4, who received the GnRH-antagonist protocol at Renmin Hospital of Wuhan University between July 2019 and September 2024. The optimal cut-off value for E₂ decrease was determined using receiver operating characteristic (ROC) curve analysis. Cycles were stratified into two groups based on the cut-off: Group A (E₂ decrease < 51%) and Group B (E₂ decrease ≥ 51%). Reproductive outcomes were compared between the two groups, and multivariable binary logistic regression analysis was performed to evaluate factors associated with clinical pregnancy. Compared with the patients in non-pregnant group, the pregnant group had lower maternal age, P levels on the hCG trigger day and duration of antagonist, but had higher BMI, AFC and the proportion of patients with E₂ decrease < 51%. The logistic regression analysis indicated that the E₂ decrease group was independently associated with clinical pregnancy after multivariable adjustment. Based on the ROC-derived cut-off value, Group A had significantly higher clinical pregnancy rates [47.4% (54/114) versus 26.8% (33/123) ( P < 0.01)] and embryo implantation rates [33.0% (60/182) versus 20.0% (39/195) ( P < 0.01)] compared with Group B. DOR patients with an E₂ decrease of less than 51% from the hCG trigger day to the embryo transfer day showed relatively better clinical outcomes under a GnRH-antagonist protocol. Monitoring peri-transfer E₂ changes may provide complementary prognostic information.