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Research Question: Is the total duration of spontaneous blastocyst collapse to re-expansion before biopsy related to ploidy and live birth rates after single euploid blastocyst transfer?, Design: This was a retrospective cohort study of 600 preimplantation genetic testing cycles for aneuploidy (PGT-A) cycles, involving 2203 biopsied blastocysts, at a large reproductive medicine centre. Features of spontaneous blastocyst collapse from full to expanded stage, before biopsy, were observed using an embryoscope viewer for embryos cultured in a time-lapse incubator. In total, 568 cycles of frozen blastocyst transfers, either single euploid or mosaic, were performed. Correlations between collapse features and PGT-A outcomes were evaluated, as well as live birth rate, following euploid embryo transfer., Results: Blastocysts with lower morphological quality or delayed development had significantly higher rates of collapse, multiple collapses, and a longer duration of collapse to re-expansion. After controlling for confounders, such as oocyte age, morphological quality of blastocyst, and day of biopsy, multivariate logistic regression revealed that the total duration of collapse to re-expansion was an independent predictor of lower euploidy rate; the multivariate OR was 0.85 (95% CI 0.77-0.95; P = 0.00). Furthermore, even with euploid embryo transfer, the probability of a live birth decreased as the total duration of collapse to re-expansion increased; the multivariate OR was 0.79 (95% CI 0.64-0.98; P = 0.033)., Conclusion: The total duration of blastocyst collapse to re-expansion could be used as a predictor of lower euploidy and live birth rate. When developing blastocyst algorithms for pregnancy prediction, the duration of spontaneous blastocyst collapse should be included as a significant variable., (Copyright © 2024 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.)

Objective: The aim of this study was to identify candidates for a morphokinetic embryo selection model for day-3 transfer through the analysis of known implantation data.Study Design: A diagnostic trial study was conducted. Two hundred twelve embryos from 109 patients participating in in-vitro fertilization (IVF) protocols.Results: In this diagnostic trial study, we analyzed cleavage times of transferred embryos with either failed (n=102) or full implantations (n=110). The logistic regression (LR) model of the relationship between the morphokinetic parameters and the implantation rate had a sensitivity of 79.61% and specificity of 47.56%. Results also showed that morphokinetic parameters such as tPNf (the time when pronuclei disappearanced), t2 (t2 for two cells), t4 (t4 for four cells) and t4-t3 were significantly different between embryos in the two groups (p<0.037). Implantation rates of embryos within the time interval of 21.27 h< t2 < 26.725 h were higher than those of embryos outside this period (60.83% vs. 40.21%, p=0.003). Fifty-seven patients with fully implanted embryos included five patients with pregnancy loss and 52 patients with live births. Embryos that met the time interval criteria for t2 and were also within the range of 11hConclusions: Selection and transfer of embryos that reach specific developmental stages within critical time intervals during IVF may improve the outcome of transfers and result in higher implantation rates and live birth rates. [ABSTRACT FROM AUTHOR]