To evaluate the effectiveness of gonadotropin-releasing hormone agonist (GnRH-a) combined with recombined-human chorionic gonadotropin (r-hCG) trigger (dual trigger) in improving the low proportion of mature oocytes in ovarian normal responders in GnRH antagonist cycles.

Retrospective study was preformed to compare the stimulation characteristics of 366in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles between March 2016 and August 2017 in Reproductive Medical Science Center of Obstetrics & Gynecology Department, Peking University Third Hospital. Patients were divided into group A (normal ovarian responders who were triggered with r-hCG only during IVF treatment resulted in low proportion of mature oocytes and failure IVF attempt, n=123), group B (dual trigger group, n=123), and group C (different patients of the corresponding period form group B, triggered with r-hCG only, n=120). The general characteristics and treatment outcomes were compared among these three groups.

The basic characteristic date including age, assisted reproductive technology (ART) indications, duration of infertility, basal hormonal level among the three groups were not statistically significant (P>0.05). The ICSI fertilization rate (90.4%vs. 83.8%， P<0.001), and the rate of metaphase-II (M_II) oocyte in group B was significantly higher than that in group A (77.6% vs. 44.7%， P<0.001). In addition, patients in group B had a significantly higher number of high-quality embryos (1.6±0.6vs. 0.3±0.3， P=0.01)， the number of embryos transferred (1.8±0.8 vs. 0.6±0.4， P=0.02), the clinical pregnancy rate (35.5%vs. 0%, P<0.001) and the live birth rate （31.8%vs. 0%， P<0.001） in the fresh embryo transfer cycle， the clinical pregnancy rate (32.1%vs. 0%, P<0.001) and the live birth rate （28.0%vs. 0%， P<0.001） in the frozen-thawed embryo transfer cycle while lower rate of cycle cancellation (10.6%vs. 27.6%， P<0.001) than group A. As compared with group C, the number of oocytes retrieved was not statistically significant, while the number of high-quality embryos (1.6±0.6vs. 4.0±2.6， P=0.02), the number of two pronucleus (2PN) embryos (5.0±2.8 vs. 6.3±3.8， P=0.03) and the clinical pregnancy rate (35.5% vs. 58.0%， P<0.001) and the live birth rate （31.8%vs. 46.8%， P=0.02） in the fresh embryo transfer cycle， the clinical pregnancy rate (32.1% vs. 51.3%, P=0.01) and the live birth rate （28.0% vs. 44.4%， P=0.03） in the frozen-thawed embryo transfer cycle were significantly lower.

For patients who have normal ovarian response but low proportion of mature oocytes, co-administration of GnRH-a and standard-dose r-hCG (dual trigger) for final oocyte maturation can improve their IVF outcome.

Dual trigger; Gonadotropin-releasing hormone antagonist; Oocyte maturation; Normal ovarian responders; Gonadotropin-releasing hormone agonist