Can pregnancy rate be improved in gonadotropin-releasing hormone (GnRH) antagonist cycles by administering GnRH agonist before oocyte retrieval? A prospective, randomized study.

Objective: To examine whether the addition of one dose of preovulatory GnRH agonist could improve implantation and pregnancy rates in GnRH antagonist IVF cycles.

Design: Prospective, randomized clinical trial.

Setting: University-affiliated IVF and infertility unit.

Patient(s): Two hundred twenty-one patients intended for GnRH antagonist protocol IVF.

Intervention(s): Patients were prospectively randomized to two groups. The control group received hCG (5,000 U) 34 hours before oocyte aspiration, and the study group received triptorelin (0.2 mg SC) in addition to hCG. All other treatment parameters were identical.

Main Outcome Measure(s): Oocyte pick-up day serum levels of E(2), P, LH, and FSH and implantation and pregnancy rates per started cycle and per completed cycle.

Result(s): A total of 200 ET cycles were carried out: 97 in the study group and 103 in the control group. None of the cycle parameters of the study or control groups differed, excepting mean oocyte pick-up day FSH (11.26 IU/L [95% confidence interval (CI) 9.88-12.52] vs. 6.27 IU/L [95% CI 5.76-8.77]) and LH levels (5.19 IU/L [95% CI 4.47-5.9] vs. 3.28 IU/L [95% CI 2.22-4.18]). The implantation rate was 19.9% (52 of 261) for the study group and 13.9% (35 of 251) for the control group. The pregnancy rate in completed cycles and the ongoing pregnancy rate per ET were significantly higher in the study group than in the control group: 29.1% (30 of 103) in the control group and 44.3% (43 of 97) in the study group, and 22.3% (23 of 103) and 36.1% (35 of 97), respectively. However, the improvement in pregnancy rate per started cycle did not reach statistical significance (40.9% vs. 28.3%).

Conclusions: The administration of triptorelin (0.2 mg) at the time of hCG administration in GnRH antagonist IVF cycles significantly improved overall and ongoing pregnancy rates in completed cycles but not in all started cycles. It is possible that this was achieved owing to an endometrial GnRH receptor effect, which should also be examined by direct endometrial studies.