O-009 Comparison of the flexible Progestin-Primed Ovarian Stimulation with the GnRH antagonist protocol in predicted suboptimal responders: a freeze-all randomized controlled trial
Authors: Shi Z , Cai H , Zhang D , Li F , Shi J , Tian L 
Published: July 2024

Study question

Is the Flexible Progestin-Primed Ovarian Stimulation (fPPOS) non-inferior to GnRH antagonist regarding fertility outcomes in women with a suboptimal response scheduled for freeze-all cycles?

Summary answer

In predicted suboptimal responders, who do not contemplate a fresh embryo transfer, the ongoing pregnancy outcomes of fPPOS was comparable to that of GnRH-antagonist protocol.

What is known already

Recent retrospective cohort studies involving donor cycles have demonstrated that Medroxyprogesterone Acetate (MPA) can be effectively and flexibly employed during the mid-follicular phase of the PPOS protocol. This approach prevents premature ovulation without compromising oocyte yields. Given its lesser degree of pituitary suppression, the fPPOS protocol may be particularly relevant for women predicted to have a suboptimal response (defined as AFC &lt; 10) where accumulation of more oocytes could enhance cumulative success rates.

Study design, size, duration

This is a open-label RCT, performed in a single IVF centre Between July 2019 and June 2023. A total of 484 women scheduled for freeze-all strategy were randomly assigned to fPPOS or GnRH-antagonist protocol. The primary outcome was live birth per woman starting stimulation following18 months of randomization. In this abstract, we present fertility outcomes following the initial frozen embryo transfer (FET) and ongoing pregnancy rates per women within a period of 6 months.

Participants/materials, setting, methods

Women (AFC&lt;10) referred for IVF/ICSI and did not intend to undergo a fresh transfer, were recruited for this study. MPA (10 mg/day) and Cetrotide (0.25 mg/day) were initiated either when the leading follicle reached 14 mm or on the sixth day of stimulation, whichever occurred first. Due to the COVID-19 pandemic, 22 women withdrew from the study at the stimulation commencement, resulting in 462 women included in the analysis. Data underwent intention-to-treat and per-protocol analyses.

Main results and the role of chance

No significant difference was observed between the two groups in terms of serum endocrine profiles and stimulation parameters, including the consumption of gonadotropins. Within the 6-month period, 79.5% of women in the fPPOS group and 84.02% in the GnRH antagonist group had undergone at least one cycle of FET (P = 0.234).The ongoing pregnancy rates per women were 48.20% (107/222) in the fPPOS group versus 52.92% (127/240) in the GnRH-anta group (RR: 0.91, 95%CI, 0.76 to 1.09, P = 0.311). There are 62 women who are ongoing pregnancy but do not reached live birth during the follow-up period. Regarding the outcomes of the initial FET cycle, there was no difference in the ongoing pregnancy rate between the two groups (49.01% vs 48.37%, RR: 1.03, 95% CI, 0.81 to 1.26, P = 0.908). Other outcomes including biochemical pregnancy rate (62.25% vs 63.59%), clinical pregnancy rate (60.26% vs 57.61%), and miscarriage rate per pregnancy (16.48% vs 15.09%), also exhibited no significant differences. The number of oocytes retrieved, two-pronuclear oocytes, viable and high-quality embryos, as well as the total number of embryos cryopreserved were also similar between groups. There was one case of premature ovulation in the fPPOS group and none in the GnRH-ant group.

Limitations, reasons for caution

Due to the distinct administration routes of the medications, blinding was not feasible in this open-label trial, which may affect the assessment of outcomes. All participants were recruited in a single center from one country, limiting the generalizability. In this abstract, we only report on the ongoing pregnancy outcomes.

Wider implications of the findings

This is the first freeze-all RCT comparing the long-term outcomes of fPPOS and GnRH antagonist in autologous ovarian stimulation cycles. Eliminating the variability of fresh and frozen transfers, the fPPOS seems an efficacious alternative for women with predicted suboptimal response, when a GnRH antagonist would have been the preferred regimen.

Trial registration number

ChiCTR2000030356