Table 1.

Embryo grading system

Grade	Number of cells	% Fragmentation	Cell symmetry
1.0	6–8 cells	<5 % fragmentation	Equal blastomeres
1.5	6–8 cells	≤10 % fragmentation	Equal blastomeres
2.0	4–6 cells	≤25 % fragmentation	Almost equal blastomeres
2.5	Cell number did not double in 24 h	≤30 % fragmentation	Unequal blastomeres
3.0	Cells did not divide	>50 % fragmentation	Unequal blastomeres

Embryo grades were determined based on numeric conversion of cell number per embryo, percent fragmentation and cell symmetry, which were evaluated on day 3 of embryo development