Table 1. Definition of time-lapse morphokinetic parameters.
Morphokinetic variables Description
tPB Appearance of second polar body
tPNa Appearance of the first pronuclei
tPN Appearance of both pronuclei
tPNf Time when both pronuclei had faded
t2 Time to 2-cell embryo
t3 Time to 3-cell embryo
t4 Time to 4-cell embryo
t5 Time to 5-cell embryo
t6 Time to 6-cell embryo
t7 Time to 7-cell embryo
t8 Time to 8-cell embryo
t9 Time to 9-cell embryo
tSC Time from insemination to initiation of compaction
tM Time from insemination to formation of a morula, completion of compaction process
tSB Time from insemination to star blastulation
tB Time form insemination to formation of a full blastocyst
tEB Time to expanded blastocyst
tH Time to hatching blastocyst, the trophectoderm herniation through the zona pellucida
tHatched Time to hatched blastocyst, the embryo has full escaped the zona pellucida
Duration variables Description
cc1 Time of  first cell cycle (t2- tPB)
cc2 Time of second cell cycle (t3-t2), from 2 to 3 cells
cc3 Time of third cell cycle (t5-t3), from 3 to 5 cells
s2 Time of synchrony of the second cycle (t4-t3), from 2 to t4 cells
s3 Time of synchrony of the third cell cycle (t8-t5), from t5 to 8 cells.