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

Abstract

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.

Keywords: Clinical pregnancy; Embryo quality; Morphokinetic parameters; Ploidy; Preimplantation genetic testing; Time-lapse monitoring.

Fig. 1

Timing of human early embryonic development. Embryonic developmental events PB2, 2PN, PNf, 2-Cell, 3-Cell, 4-Cell, 5-Cell, 8-Cell, tPB2, tPNa, tPNf, CC2, S3, tSC, tM, tSB, tB, Compaction, Morula, Blastocyst cavity formation, Blastocyst are shown in Graphic. We determined the precise times and measured them within hours of ICSI

Fig. 2

Comparative analysis of kinetic parameters of early embryonic development of high-quality blastocysts and non-high quality blastocysts. Box plots indicate the mean, standard deviation, and time to minimum and maximum (A) and the duration of the associated developmental events (B) of the kinetic parameters of embryo development. Red and purple colors indicate high-quality blastocysts and non-high quality blastocysts, respectively. * denotes p < 0.05, ** denotes p < 0.01, and p < 0.05 indicates a significant difference between the two groups

Fig. 3

Comparison of parameters analysed for embryonic developmental dynamics of blastocyst chromosome conditions. Box plots represent the mean, standard deviation and time to minimum and maximum (A) and duration of relevant developmental events (B) of different embryonic developmental morphokinetic parameters between aneuploid and aneuploid blastocysts, with red and purple boxes indicating blastocysts with normal chromosomes (aneuploid) and abnormal chromosomes (aneuploid), respectively. * denotes p < 0.05, ** denotes p < 0.01, and p < 0.05 indicates a significant difference

Fig. 4

Thresholds for embryo developmental morphokinetic parameters and clinical pregnancy outcomes. Parameter thresholds were mainly based on the values of embryonic developmental morphokinetic parameters with higher pregnancy rates obtained by quartile grouping. Comparisons between groups were statistically analysed using the chi-square test, * denotes p < 0.05, ** denotes p < 0.01, and p < 0.05 denotes a statistically significant difference