Each embryo transferred was evaluated for blastomere size and fragmentation. Embryos were graded as follows. Those with equal blastomere size and no fragmentation were considered Grade 1; those with blastomeres of equal size with slight fragmentation (<20 %) were Grade 2;those with blastomeres of unequal size but no fragmentation were Grade 3; those with blastomeres of equal or unequal size and moderate fragmentation (20 %-50 %) were Grade 4; and those with unrecognizable blastomeres and severe fragmentation (>50 %) were Grade 5.