Modified double trigger versus recombinant hCG alone for final oocyte maturation in IVF-ICSI: Impact on oocyte and embryological outcomes.

Abstract

Objective: To evaluate whether a modified double trigger (recombinant hCG -36 h plus GnRH agonist -34 h) improves oocyte maturation and embryological outcomes compared with r-hCG alone in IVF-ICSI cycles, and whether effects differ by age and ovarian reserve.

Methods: Retrospective single-center cohort study included 80 IVF-ICSI cycles performed between 2023 and 2025, comparing a modified double trigger (n=42) with r-hCG alone (n=38). The primary outcome was oocyte maturation rate (MII/total oocytes). Secondary outcomes included total and MII oocytes, fertilization, cleavage, blastulation, day-3 and day-5 embryo counts, and binary endpoints. Prespecified subgroup analyses were conducted by age and antral follicle count (AFC), Adjusted generalized regression models were applied for key outcomes. Spearman correlation assessed the association between maximum follicular diameter and maturation in AFC <6 and in women aged ≥41 years.

Results: Baseline characteristics were comparable. Overall oocyte maturation rates were similar between groups (median 75.7% in both; p=0.691). In AFC <6, unadjusted analyses showed higher day-5 embryo yield with the modified double trigger, without independent associations in adjusted models. In women aged ≥41 years, the modified double trigger was associated with higher numbers of 2PN oocytes and day-3 embryos, and achieving ≥2 day-5 embryos occurred more frequently (33.3% vs. 0%). In adjusted analyses, double trigger remained independently associated with a higher number of MII oocytes in this subgroup.

Conclusions: The modified double trigger did not improve overall oocyte maturation. Exploratory analyses suggest a potential benefit on downstream embryological outcomes in poor prognosis subgroups, supporting further prospective evaluation of trigger timing strategies.