https://www.youtube.com/watch?v=SPLHjFis_4M

第一次分裂大多發生在受精後28小時左右

若提前到25小時內則稱之為早期分裂

通常早期分裂之胚胎懷孕率明顯較高(2倍)

若受精後32小時仍未分裂  通常胚胎預後不佳

https://www.researchgate.net/figure/Sample-model-of-a-quality-grading-system-for-oocytes-and-embryos-A-Oocyte-grading_fig1_275098392

This occurrence is checked 23-27 hours after insemination. At this moment, embryos with two blastomeres are classified as early cleavage (EC) embryos and those that do not reach this stage with intact nuclear membranes are classified as no early cleavage (NEC) embryos.  EC embryos show more than two times the pregnancy rate and three times the implantation rate compared with non EC (NEC) embryos.