Triggering with Human Chorionic Gonadotropin or a Gonadotropin-releasing Hormone Agonist in Gonadotropin-releasing Hormone Antagonist-treated Oocyte Donor Cycles: Findings of a Large Retrospective Cohort Study

Objective: To compare pregnancy rates and the incidence of ovarian hyperstimulation syndrome (OHSS) in donor stimulation cycles where final maturation of oocytes was induced with recombinant hCG or GnRH agonist.

Design: Retrospective, cohort study.

Setting: Private infertility clinic.

Patient(s): A total of 1171 egg donors performing 2077 stimulation cycles.

Intervention(s): Controlled ovarian hyperstimulation of egg donors with GnRH antagonist protocol triggered with recombinant hCG (rhCG; 250 microg) or GnRH agonist (triptorelin 0.2 mg) based on the physician's decision.

Main Outcome Measure(s): Proportion of mature and fertilized oocytes per donor cycle; clinical, ongoing pregnancy and implantation rate in recipients; and incidence of moderate/severe OHSS in oocyte donors.

Result(s): The proportion of mature oocytes was comparable, whereas the difference in the fertilization rate reached statistical significance (65% vs. 69%). No significant differences were observed in the implantation rate or clinical and ongoing pregnancy rates per ET. The incidence of moderate/severe OHSS was 1.26% (13/1031; 95% confidence interval [CI], 0.74-2.15) and 0% (0/1046; 95% CI, 0.00-0.37) in the rhCG and GnRH agonist groups, respectively.

Conclusion(s): Recipient outcome was not significantly different when using oocytes from GnRH antagonist-treated donor cycles triggered with hCG or GnRH agonist. However, GnRH agonist triggering was associated with a lower incidence of moderate/severe OHSS in egg donors.