Which euploid single embryo transfer strategy is preferable in advanced maternal aged; Fresh versus frozen

Abstract Purpose: Herein, we aimed to compare two commonly used single embryo transfer (ET) strategies, fresh and frozen-thawed euploid blastocyst transfer protocols via trophectoderm biopsy after preimplantation genetic screening (PGS) in advanced maternal aged (AMA).Study Design: This study was designed as a single-center cohort study.A total of 317 patients aged older than 37 years old who underwent single fresh or frozen-thawed day five or day 6 ET with trophectoderm biopsy examined retrospectively. PGS was performed on the embryos of 138 patients, and fresh transfers were preferred, while embryos of 179 patients were vitrified, and then frozen-thawed euploid single ET was chosen after PGS. Percentage of the euploid embryo, implantation rates, pregnancy rates, pregnancy continuity rates, clinical and biochemical abortion rates were compared.Results: Age, body mass index, infertility duration,previous ART cycles,days of stimulation, andAnti-Mullerian hormone levels did not reveal statistically significant difference between the groups. The retrieved oocyte, MII oocytes, and fertilized ovum (2PN) numbers were higher in the Frozen-thawed group. The percentage of a euploid embryo (32% vs. 34.8%) was similar between the groups. Implantation rates (46% vs. 62%), pregnancy rates (49% vs. 66%), ongoing pregnancy rates (36.7% vs. 52.6%), and live birth percentage (35.4% vs. 51.6%) were significantly higher in the frozen-thawed embryo transfer group, while the clinical and biochemical abortion rates did not reveal significant difference. Conclusion: Frozen-thawed single euploid ET provides sufficient time for comprehensive genetic evaluations and increases the rates of implantation and pregnancy rates compared to the fresh single euploid ET in AMA patients with PGS.