Total duration of spontaneous blastocyst collapse during the expansion stage is an independent predictor of euploidy and live birth rates

Research question: Is the total duration of blastocyst spontaneous collapse to re-expansion before biopsy related to ploidy and live birth after single euploid blastocyst transfers? Design: This study conducted a retrospective cohort study of 600 preimplantation genetic testing cycles for aneuploidy (PGT-A) cycles, involving 2203 biopsied blastocysts, at a large reproductive medicine center. Features of blastocyst spontaneous collapse from full to expanded stage, before biopsy, were observed using an embryoscope viewer for embryos cultured in a time-lapse incubator. A total of 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 following euploid embryo transfers. Results: Blastocysts with lower morphological quality or delayed development had significantly higher rates of collapse, multiple collapses, and a longer duration of collapse and re-expansion. After controlling for confounders, such as oocyte age, morphological quality, and day of the biopsy, multivariate logistic regression revealed that the total duration of collapses 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: Total duration of blastocyst collapse to re-expansion could be used as a predictor of lower euploidy and the live birth rate. When developing blastocyst algorithms for pregnancy prediction, the duration of blastocyst spontaneous collapse should be included as a significant variable.