Researchers looked at two ways to stimulate the ovaries for IVF – a GnRH‑antagonist protocol and a fixed progestin‑primed protocol – and found that they gave almost identical results in terms of eggs retrieved, how many eggs matured, fertilisation, embryo development, implantation and overall pregnancy rates. The level of hormone (LH) suppression before the final egg‑maturation step was also the same for both methods.

Investigators have compared progestin-primed ovarian stimulation (PPOS) and conventional stimulations in multiple studies, however, with contrasting observations with respect to <i>in vitro</i> fertilisation (IVF) cycle outcomes. The extent of serum luteinising hormone (LH) suppression has not been studied much between the protocols. The primary aim of this study was to compare IVF cycle outcomes in terms of oocyte yield, maturation rate, fertilisation rate, blastulation rate, implantation and cumulative pregnancy rate between gonadotropin-releasing hormone (GnRH) antagonist protocol and fixed PPOS protocol. The secondary aim was to compare the extent of pituitary suppression as reflected by serum LH before final oocyte maturation between both the protocols. This was a retrospective observational cohort study. All ovarian stimulation cycles, either performed as GnRH-antagonist or as fixed PPOS, between 1^st October 2023 and 15^th July 2024, at a tertiary level IVF centre were included. Egg freezing cycles and donor egg cycles were excluded. Statistical tests applied were Student's <i>t</i>-test two-tailed for interval/ratio variables and the Chi-square test for nominal variables with a significance level of 0.05. The total number of cycles was 189, of which 87 (46.03%) cycles were in the GnRH antagonist group and 102 (53.96%) in the PPOS group. The groups were similar with respect to age, anti-M&#xfc;llerian hormone, body mass index as well as total gonadotropin consumption. There was no significant difference observed for the number of oocytes (<i>P</i> = 0.92), maturation rate (<i>P</i> = 0.07), fertilisation rate (<i>P</i> = 0.84), blastulation rate (<i>P</i> = 0.52), implantation rate (<i>P</i> = 0.36) and cumulative pregnancy rate (<i>P</i> = 0.63). The serum LH values before final oocyte maturation (suppressed LH) were similar (<i>P</i> = 0.09) in both the protocols. IVF cycle outcomes with respect to oocyte yield, maturation rate, fertilisation rate, blastulation rate, implantation rates and cumulative pregnancy were comparable between GnRH antagonist and PPOS cycles. Furthermore, the extent of pituitary suppression, reflected by the serum LH levels before final oocyte maturation, was similar between the groups as observed in our analysis. However, these findings need to be validated by prospective studies or randomised trials with equal patient division.