[Chromosomal aneuploidy and pregnancy outcomes for D5/D6 blastocysts from patients undergoing PGT-A treatment].

Objective: To compare the prevalence of chromosomal aneuploidies and pregnancy outcomes of D5 and D6 blastocysts subjected to preimplantation genetic testing for aneuploidy (PGT-A).
Methods: Clinical and laboratory data of 268 couples who underwent PGT-A at the Reproductive Center of the First Affiliated Hospital of Zhengzhou University from September 2018 to September 2020 were collected. The prevalence of chromosomal aneuploidies and pregnancy outcomes of D5/D6 biopsied blastocysts were compared.
Results: Compared with D6 blastocysts, the euploidy rate of D5 blastocysts was significantly higher (49.1% vs. 41.1%, P = 0.001 1), whilst their aneuploidy rate was significantly lower (50.9% vs. 58.9%, P = 0.001 1). The rate of numerical abnormalities of D6 blastocysts was significantly higher than that of D5 blastocysts (27.9% vs. 20.2%, P = 0.000 5). For patients under 35 years old, the euploidy rate of D5 blastocysts was significantly higher than that of D6 blastocysts (53.8% vs. 44.3%, P = 0.001), whilst the numerical abnormality rate was significantly lower (16.3% vs. 23.9%, P = 0.001). For both D5 and D6 blastocysts, the euploidy rates for patients <= 35 were significantly higher than those for > 35. The elder group had the lowest rates for aneuploidies and live births. Compared with those receiving D6 blastocysts transplantation, the pregnancy rate, implantation rate and live birth rate for those receiving thawed D5 blastocysts transplantation were significantly higher (60.2% vs.37.0%, P = 0.000 3; 59.1% vs.37.0%, P = 0.000 6; 47.7% vs. 28.3%, P = 0.002).
Conclusion: For patients undergoing PGT-A, the chromosomal euploidy rate for D5 blastocysts is higher than that for D6 blastocysts, and the clinical outcome of D5 blastocysts with normal signal is better than that of D6 blastocysts. Elder patients have a higher rate of aneuploidies.