Comparison of different ovarian stimulation in poor responders

Abstract

Background: The adequate retrieval of oocytes is one of the fundamental factors contributing to the success of IVF treatment. Clinically, the effectiveness of controlled ovarian stimulation is dependent on ovarian response, which can be classified as poor, normal, or hyper-response. The prevalence of poor responders among all IVF patients ranges from 9% to 25%. As a result of ovarian stimulation, multiple follicles are enlarged, resulting in a rapid increase in estradiol levels and conditions for premature LH surges in IVF. Two gonadotropin-releasing hormone (GnRH) analogs, GnRH agonist and GnRH antagonist, have been used to solve these problems, both of which are effective in blocking premature LH surge. But still, the best protocol for the good prognosis of IVF patients is generally debated. Aim: This study aimed to compare the clinical outcomes of two ovarian stimulation protocols—GnRH long agonist and GnRH antagonist—in poor ovarian responders undergoing in vitro fertilization (IVF) with fresh embryo transfer in a Mongolian population. Materials and Methods: A prospective study was conducted at the Unimed International Hospital’s IVF center between January 2023 and May 2024. A total of 114 infertile women identified as poor responders, based on the Bologna criteria, were randomized into two groups: GnRH long agonist protocol (n=56) and GnRH antagonist protocol (n=58). The primary outcome was the clinical pregnancy rate, and secondary outcomes included the number of oocytes retrieved, ovarian stimulation parameters, and embryo quality. Statistical significance was set at p<0.05. Results: The GnRH long agonist group had significantly longer stimulation duration (10.0±0.7 vs. 9.0±0.5 days, p<0.01) and higher gonadotropin requirements (3219.7±199.0 IU vs. 2779.2±325.4 IU, p<0.01) compared to the GnRH antagonist group. Despite a higher ovarian sensitivity index (1.13±0.4vs.1.34±0.56) and follicular output rate (68.9%±11.8% vs. 40.7%±10.9%, p<0.01) in the long agonist group, the number of oocytes retrieved, fertilization rate, and embryo quality were comparable between the two groups. The clinical pregnancy rates were also similar, with 7.14% in the GnRH long agonist group and 10.3% in the GnRH antagonist group (p=NS). Conclusion: Both the GnRH long agonist and GnRH antagonist protocols resulted in similar clinical outcomes in poor ovarian responders, despite differences in ovarian stimulation characteristics. The choice of protocol should be individualized based on patient-specific factors, as neither protocol demonstrated a clear advantage in terms of pregnancy outcomes.