Exploring key embryonic developmental morphokinetic parameters that affect clinical outcomes during the PGT cycle using time-lapse monitoring systems.

Research Question: Is it possible to predict blastocyst quality, embryo chromosomal ploidy, and clinical pregnancy outcome after single embryo transfer from embryo developmental morphokinetic parameters?

Design: The morphokinetic parameters of 1011 blastocysts from 227 patients undergoing preimplantation genetic testing were examined. Correlations between the morphokinetic parameters and the quality of blastocysts, chromosomal ploidy, and clinical pregnancy outcomes following the transfer of single blastocysts were retrospectively analyzed.

Results: The morphokinetic parameters of embryos in the high-quality blastocyst group were significantly shorter than those in the low-quality blastocyst group (p < 0.05). In contrast, the CC2 time was significantly prolonged (p < 0.05). On chromosomal analysis of biopsy blastocysts nourished by trophectoderm cells, in comparison to euploid embryos, aneuploid embryos exhibited significant extensions in tPNa, S3, tSC, tM, tSB, and tB (p < 0.05), with a simultaneous significant reduction in CC2 time (p < 0.05). After adjusting for age and body mass index through logistic regression analysis, late morphokinetic parameters, namely tM (OR 0.96; 95% CI 0.93-0.99), tSB (OR 0.94; 95% CI 0.90-0.97), and tB (OR 0.93; 95% CI 0.90-0.97), emerged as independent risk factors influencing the development of embryos into high-quality blastocysts. S3 (< 12.01 h), t8 (< 62.48 h), and tPB2 (< 3.36 h) were potential predictors of a successful clinical pregnancy after blastocyst transfer.

Conclusion: Morphokinetic parameters showed correlations with blastocyst quality, chromosomal status, and clinical pregnancy outcomes post-transfer, making them effective predictors for clinical results. Embryos with relatively rapid development tended to exhibit better blastocyst quality, chromosomal ploidy, and improved clinical pregnancy outcomes. The late morphokinetic parameter, S3, demonstrated a strong predictive effect on blastocyst quality, chromosomal ploidy, and clinical pregnancy outcomes.