The Superiority and Feasibility of Fresh Single Blastocyst Transfer in the Gonadotropin-Releasing Hormone Antagonist Protocol

Objective: To assess the advantage and feasibility of fresh single blastocyst transfer (SBT) with the GnRH antagonist (GnRH-ant) protocol. Design: Retrospective cohort study. Setting: Single center study. Population: Patients (n=4760) received first cycle of GnRH-ant protocol. Methods: The embryological and clinical outcomes were compared between SBT and day-3 double embryo transfer (DET) groups. A nomogram model was constructed and validated. Main Outcome Measures: Live birth rate (LBR). Results: The SBT and DET groups had comparable clinical pregnancy rate (CPR) (49.8% vs. 51.7%) and LBR (41.6% vs. 45.2%). For good-quality embryos, SBT and DET subgroup also had comparable CPR (61.6% vs. 57.1%) and LBR (52.7% vs. 50.9%). For patients ≥ 30 years, SBT group showed significantly higher implantation rate than DET group (30–34 years: 52.8% vs. 32.5%, P < 0.001; ≥ 35 years: 41.8% vs. 28.4%, P = 0.039). The SBT group showed significantly lower multiple pregnancy rate (MPR) than DET group (2.60% vs. 34.3%, P < 0.001). A nomogram model was constructed based on six significant independent predictors (age, gonadotropin starting dose, number of retrieved oocytes, fertilized oocytes, day-3 available embryos, and day-3 good-quality embryos) to predict the possibility of blastocyst formation. The area under the receiver operating characteristic curve of the training set and validation set was 85.2% (95% CI: 0.839–0.866) and 84.0% (95% CI: 0.819–0.860), respectively. Conclusions: The SBT strategy can guarantee favorable CPR, LBR and low MPR. Additionally, the nomogram model could be promising in terms of helping physicians to design individualized ET strategies.