Comparison of Clinical Outcomes in the Slow-Developing Blastocysts With or Without Preimplantation Genetic Testing-Aneuploidy on Day 6 in the Frozen-Thawed Cycle.

OBJECTIVES

This study investigated the potential of the slow-developing blastocysts using preimplantation genetic testing-aneuploidy (PGT-A) in patients undergoing frozen-thawed embryo transfer, stratified by age.

METHODS

A retrospective analysis was performed including a total of 743 cycles, the first frozen embryo transfer (FET) cycle with single embryo transfer, who underwent treatment between January 2020 and July 2023 in a single fertility centre, Gangnam CHA Fertility Center. A total of 743 cycles, in which we performed intracellular sperm injection and freeze-all strategy, from 743 patients were included. The patient group was divided into 4 groups as follows: group 1 (G1), 208 FET on day 5; group 2 (G2), 177 FET with PGT-A on day 5; group 3 (G3), 220 FET on day 6; group 4 (G4), 138 FET with PGT-A on day 6. We also divided into 2 groups-under 35 years of age and over 35 years of age-and performed the analysis separately for each group.

RESULTS

In the under 35 years of age group, there were no significant differences in clinical pregnancy and miscarriage rates in G1 and G2 (67.2% vs. 63.8%, not statistically significantly different). Also, G4 had a higher clinical pregnancy rate than G3, but it was not significant (51.8% vs. 54.7%, not statistically significantly different). In the 35 years or older group, G2 had higher pregnancy rates than G1 and lower miscarriage rates (clinical pregnancy rate: 43.3% vs. 67.7%, P = 0.001, miscarriage rate: 22.5% vs. 3.4%, P = 0.001). In addition, G4 had a higher pregnancy rate than G3 and a lower miscarriage rate (clinical pregnancy rate: 31.8% vs. 46.9%, P = 0.003, miscarriage rate: 22.9% vs. 2.2%, P = 0.023).

CONCLUSIONS

In the under-35-year-old group, PGT-A on day 5 and day 6 showed a high pregnancy rate and a low miscarriage rate. Therefore, using PGT-A seems advantageous for patients of an advanced maternal age.