Development potentiality of day-3 embryo in women undergoing in vitro fertilization-embryo transfer treatment

Objective To evaluate the morphological assessment on embryonic developmental potentiality by investigating the blastula formation from day-3(D3) embryos. Methods A total of 1 185 infertile couples underwent in vitro fertilization- embryo transfer treatment were enrolled, of which the females were 21- 45 years old with mean age of 30.9 years old. Each blastocyst from naturally inseminated 8 148 D3 embryos was cultured in 25 μL droplet of culture medium, and highquality blastocyst formation rates were compared. Results The highest blastocyst rate was observed in 8-cell grade ⅠD3 embryos(76.49 %), which was significantly higher than that of 8-cell(35.10 %), 9-cell(68.12 %) or 9-cell(70.36 %) grade ⅠD3 higher rate of blastocyst formation in 8-cell grade ⅠD3 embryos was also observed in female 35-year-old as compared to those of ≥ 35-year-old(P 0.01). In subgroup ≥ 35-year-old, the blastocyst formation rate from D3 embryos was sequentially ordered as 8-cell grade Ⅰ(68.29 %) 8-cell grade Ⅰ(68.06 %) 7-cell grade Ⅰ(40.82 %) D3 embryos,with statistically significant differences among them(P 0.01). Conclusion It is demonstrated that 8-cell gradeⅠD3 embryo is optimal for cleavage-stage embryo transfer, however, 7- and 9-cell grade Ⅰ and Ⅱ embryos are the high-quality embryos.The criteria for D3 embryos in female ≥ 35-year-old needs to be further studied.