Table 1. Atypical features that can be identified with time-lapse monitoring incubator.
Feature	Description	Study/Reference
-Pronuclei (PN) formation -Singamy	Wrong PN movement in the cytoplasm	Coticchio et al., 2018 Azzarello et al., 2012
-Appearance of two PN -Pronuclei reappearance	-Asynchronous appearance and disappearance of PN -Pronuclei fading and reappearance	Coticchio et al., 2018
-Pronuclei size	Difference in pronuclear areas before pronuclear fading	Otsuki et al., 2017
-PN fragmentation -PN fusion	-Formation of micronuclei -A pronucleus formed by the fusion of two preexisting pronuclei	Mio & Maeda, 2008 Coticchio et al., 2018
- Unipolar cleavage furrow -Tripolar cleavage furrow -Pseudofurrows	-Appearance of cleavage furrow on one site of the zygote -Appearance of three cleavage furrows -Zygote presenting oolemma ruffling before cytokinesis	Wong et al., 2010 Athayde Wirka et al., 2014
-Absent cleavage -Reverse cleavage	-Arrest at zygote stage -Fusion of two cells into one blastomere	Barrie et al., 2017 Desai et al., 2014
Direct cleavage	Cleavage of zygote to three cells or one blastomere divides to three cells	Athayde Wirka et al., 2014 Barrie et al., 2017 Meseguer et al., 2011
Blastomere movement	Blastomere and cytoplasm movement before division	Ezoe et al., 2019
Multinucleation	Blastomere with more than one nucleus	Desai et al., 2014 Hashimoto et al., 2016
Internalization of cellular fragments	Fragments reabsorbed into one blastomere	Mio & Maeda, 2008
Irregular chaotic division	Disordered cleavage behaviour with uneven cleavages and fragmentation	Athayde Wirka et al., 2014 Barrie et al., 2017 Meseguer et al., 2011
Early compaction	Formation of tight junctions between blastomeres in day 3 embryos	Iwata et al., 2014
Cell exclusion	Exclusion of one or more blastomeres from the morula formation	Coticchio et al., 2019)
Spontaneous Blastocyst collapse	Collapse of blastocyst with complete disappearance of blastocoel cavity	Marcos et al., 2015 Sciorio et al., 2020a Sciorio et al., 2020b

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