LUTEAL PHASE STIMULATION PROVIDES HIGHER MATURE OOCYTE AND BLASTOCYST YIELD IN PATIENTS UNDERGOING A DOUBLE STIMULATION IN THE SAME OVARIAN CYCLE (DUOSTIM) PROTOCOL

Abstract

To compare the mean numbers of mature oocytes and blastocysts obtained after follicular phase stimulation (FPS) and luteal phase stimulation (LPS) from infertile patients undergoing a Double stimulation in the same ovarian cycle (DuoStim) protocol Retrospective analysis of DuoStim cycles performed in unselected infertile patients between 2018 - 2020 in a single private center. The DuoStim protocol included recombinant gonadotropins (up to 300 IU daily) and GnRH antagonists in both simulations with 5 -6 days gap between phases. Ovulation was triggered with a GnRH agonist. Mature eggs were frozen after the FPS and fertilized together with fresh retrieved oocytes at the end of the LPS; cultured to until blastocyst-stage and electively vitrified. Stimulation characteristics and laboratory outcomes variables were compared between the FPS and LPS. Clinical pregnancy and ongoing pregnancy rates were evaluated for those patients who underwent subsequent frozen-thawed embryos transfers (FET). 39 patients underwent 40 treatment cycles. Mean female age was 38.5±3.5 (range: 30-44 years) with 82,5% having poor ovarian response fulfilling the Bologna criteria. Main indications were oocyte accumulation/embryo freezing in low (n=33) or normo-responder (n=7) patients. PGT-A was performed in 17 patients. There were no significant differences in stimulation duration (11.0±1.5 versus 10.9±2.1, p=0.81) between FPS and LPS. Total DuoStim treatment duration was 20.3±5.7 (range:15-34 days). The number of mature oocytes retrieved (3.15±2,3 vs 4.8±3.8, p=0.02), oocytes fertilized (1.7±1.5 vs 2.9±2.4, p=0.007) and blastocysts vitrified (0.9±0.9 vs 1.7±1.9, p=0.02) was significantly higher in the LPS compared to FPS. 19 patients underwent subsequent FET. The clinical pregnancy rate and ongoing pregnancy rate per transfer were 36,8 % (7/19) and 31,5 % (6/19) respectively. LPS of DuoStim achieved higher mature oocyte recruitment and blastocyst yield and might potentially improve reproductive outcomes. Further studies focused on understanding the follicular waves and the clinical implications of LPS in IVF are warranted.