O-130 Initiation of ovarian stimulation in the late follicular phase, a randomized controlled trial

Abstract Study question Does late follicular phase stimulation yield similar outcomes compared with conventional early in a GnRH antagonist protocol oocyte donors? Summary answer Late is not inferior terms of number oocytes to protocol. What known already In patients undergoing fertility preservation for medical reasons, has been effectively used, resulting numbers total and mature obtained, maturation rate, yield, fertilization rates ovarian stimulation. Because LH suppression by endogenous progesterone the luteal phase, there less need use antagonist. design, size, duration This an open label, 3, non-inferiority, randomized controlled trial using two-arm design 1:1 allocation ratio. The study included 71 donors between 18 36 years, regular menstrual cycle length BMI 19-35 kg/m2, who underwent November 2018 May 2022. Patients were allocated either start (Group A, n = 36), or B, 35). Participants/materials, setting, methods Group followed fixed r-FSH 225IU daily. daily was initiated when dominant follicle hormonal values observed, added if serum LH-levels >10IU/L. primary outcome cumulus-oocyte-complexes (COCs). Secondary endpoints oocytes, consumption gonadotropins, stimulation, days cost Main results role chance Using intention-to-treat analysis, did differ A B (17.7±10.0 vs 17.2±9.1, p 0.82, difference 0.49 ,95% CI (-4.04 5.03)). per after excluding 4 patients, no (18.2±9.7 18.8±7.8, 0.62, -0.6, 95% (-4.9 3.7)).The (14.1±8.1 12.7±8.5, 0.48). none treatment arms OHSS observed. shorter than (10.0±1.6 10.9±1.5 days, 0.01). amount used lower group (2240.7±313.9 IU 2453.9±330.1 0.008). approximately 6 while only one patient prescribed (6.0±1.4 0.13±0.7 < 0.001). There significant medication both protocols (1147.9±182.8 € 979.9±129.0 0.001), i.e. reduction 15% as A. Limitations, reasons caution limitation lack embryology data. adaptations donation program our center over this contains mix fresh frozen cycles, leading very heterogenous group, making correct interpretation data difficult. Wider implications findings efficient oocytes. It patient-friendly, reduced injections. Trial registration NCT03767218