P-683 Live birth rate following medicated frozen-thawed embryo transfer with or without GnRH-antagonist (Cetrotide) pituitary suppression. A randomised, controlled pilot trial

Abstract Study question Does the administration of GnRH-antagonist (Cetrotide) in medicated frozen-thawed embryo transfer (FET) cycles improve live birth (LBR) or cycle cancellation rate? Summary answer Live and were similar with without Cetrotide. However, for threatened ovulation was statistically significantly lower when Cetrotide administered. What is known already During FET, endometrial development must be synchronized, window implantation dependent on duration progesterone. Suppression spontaneous key to maintaining synchrony. There are insufficient data regarding use supplementary pituitary suppression FET. A recent Cochrane review identified one small RCT comparing rate between FET GnRH-agonist pretreatment. The study suggested benefit GnRH-agonist, but not monitored ovulation. One compared agonist showing better clinical pregnancy GnRH-antagonist. No published has versus design, size, We conducted an open, two-arm, single-centre, randomised, controlled trial Target recruitment 300. stopped due Covid-19 pandemic. Recruitment occurred 23rd January 2019 11th March 2020 ended at 161 participants. Analysis undertaken intention-to-treat basis, as primary outcome. Participants/materials, setting, methods Patients given oestradiol 2mg orally TDS. Once endometrium ≥7mm, vaginal progesterone commenced, sixth day group 0.25mg SC OD from days 1-7. Urine test done 11 following progestogen continued 10 weeks gestation. Cycles cancelled “threatened ovulation” if daily urinary LH-surge testing positive ovarian follicle (≥12mm) growing. Main results role chance patients randomised (Cetrotide: 76, no Cetrotide: 85). Six withdrawn after randomisation (three withdrew consent, two did start, natural pregnancy). 155 participants started treatment 73, 82) 140 had 68, 72). LBR groups 39% (30/76), (29/85): 34%; OR 0.79, 95% CI 0.42 - 1.51), (42% 38%; 0.87; 0.47-1.63), (52% 49%; 0.83; 0.44 – 1.56), biochemical (20% 24%; 1.25; 3.58) miscarriage (7% 10%; 1.55; 0.24 9.97). In group, 7% cancelled, 12% (NS). 0% 5% (OR 1.05; 1.001 1.105). Baseline characteristics (age oocyte retrieval, age parity, subfertility diagnosis, number oocytes retrieved, viable blastocysts, proportion IVF/ICSI, thickness, embryos transferred, quality) groups. Limitations, reasons caution limited by fact it unblinded, a single site underpowered early cessation. Wider implications findings Results suggest effect higher risk taking This clinically significant requires further study, increase costs birth. Trial registration EudraCT Number: 2018-001915-63