Gonadotropin-releasing hormone (GnRH)-antagonist versus GnRH-agonist in ovarian stimulation of poor responders undergoing IVF

The objective of this study was to compare the efficacy of GnRH-antagonists to GnRH-agonists in ovarian stimulation of poor responders undergoing IVF. Retrospective analysis of our data revealed that 56 patients underwent treatment with a GnRH-agonist according to the flare-up protocol. Patients failing to achieve an ongoing pregnancy (n = 53) were subsequently treated in the next cycle with a GnRH-antagonist according to the multiple-dose protocol. Main outcome measures included the clinical pregnancy and implantation rates. While ovulation induction characteristics and results did not differ between the two protocols, the number of embryos transferred was significantly higher (P = 0.046) in the GnRH-antagonist than in the GnRH-agonist stimulation protocol (2.5 +/- 1.6 vs. 2.0 +/- 1.4, respectively). The clinical pregnancy and implantation rates per transfer in the GnRH-antagonist group appeared higher than in the GnRH-agonist, but did not differ statistically (26.1 and 10.7 compared with 12.2 and 5.9%, respectively). However, the ongoing pregnancy rate per transfer was statistically significantly higher (P = 0.03) in the GnRH-antagonist than in the GnRH-agonist group (23.9 vs. 7.3%, respectively). Applying GnRH-antagonists to ovarian stimulation protocols may offer new hope for IVF poor responder patients. However, further controlled randomized prospective studies with larger sample sizes are required to establish these results.