Usefulness of morphokinetics in early stages of embryonic development as a predictive value of blastocyst formation and quality

Although culture to blastocyst has been associated with an increase in implantation rates, sometimes this is not possible due to multiple casuistry. Thus, trying to relate morphokinetics in early stages with the capacity to form blastocysts and their quality can be very useful. Timelapse incubators help to establish the exact moment in which blastomere divisions occur, evaluating embryo morphology in a non-invasive way and allowing a better selection of embryos to be transferred and/or vitrified. The aim of this study is to evaluate the predictive value of t4 (hours elapsed from insemination to 4-cell division) in the formation of blastocysts and their quality. Retrospective study with 385 blastocysts from patients undergoing IVF-ICSI treatment in our hospital from June to December 2023. There are no significant differences, neither in age nor in stimulation protocols, in the different groups. Both ICM and TM were classified based on the ASEBIR proposal. Statistical analysis by ANOVA for mean comparison. Significant differences (p value = 0.000) were observed when comparing T4 between embryos that did not reach blastocyst (47.9 ±19.55 min) and those that did (37.9 ±10.31min). No significant differences were observed in T4 in terms of quality of useful blastocysts (A: 36.34; B: 36.46 and C: 36.35). In contrast, a certain tendency to compact morula formation in shorter time is observed with higher final blastocyst quality (A: 83.56; B: 84.72 and C: 87.46). T4 has a high potential as a predictive value in blastocyst formation and, consequently, gestation, allowing us to determine which embryos are best to transfer and/or cryopreserve.