Hormonal Dynamics around the Time of Trigger Injection Administration Predict Oocyte Yield in Planned Oocyte Cryopreservation Cycles

Purpose To evaluate whether peri-trigger serum hormone dynamics are associated with mature oocyte yield in planned oocyte cryopreservation cycles across ovulation trigger protocols. Methods We conducted a retrospective study of patients aged ≤ 42 years undergoing their first planned oocyte cryopreservation cycle between January 2021 and March 2024 at a single academic center. Cycles used gonadotropin-releasing hormone agonist (GnRHa) alone, human chorionic gonadotropin (HCG) alone, or dual trigger. Serum luteinizing hormone (LH), progesterone (P4), and HCG were measured on the day of trigger and post-trigger; estradiol (E2) was measured prior to and on the day of trigger, and change in E2 (ΔE2) was calculated. The primary outcome was the number of mature oocytes retrieved. Multivariable regression adjusted for age, body mass index, anti-Müllerian hormone, and cycle length. Results Among 677 patients, higher day-of-trigger LH levels were independently associated with fewer total and mature oocytes across trigger types (IRR 0.97, IRR 0.94, respectively; p < 0.05), with the strongest association observed in GnRHa-only cycles. Post-trigger LH and HCG levels were not associated with oocyte outcomes. Higher day-of-trigger and post-trigger P4 levels were positively associated with total and mature oocyte yield in GnRHa-only and dual trigger cycles (IRR 1.01–1.11, p < 0.001). An increase in E2 from pre-trigger to trigger day was associated with higher oocyte yield (IRR 1.00, p < 0.05), whereas an E2 decline was associated with reduced yield, particularly in HCG-only cycles. Conclusions Peri-trigger hormone dynamics are associated with mature oocyte yield in planned oocyte cryopreservation cycles and may help contextualize cycle-to-cycle variability across trigger protocols.