Analysis of related factors for blastocyst development

Objective To explore related factors for blastocyst development during the in-vitro fertilization(IVF) and Intracytoplasmic sperm injection(ICSI) cycles.Methods D3 surplus embryos after embryo t ransfer or Vitrification from IVF/ ICSI cycles were cultured into blastocyst by the sequential method,then the blastocyst development were observed.Results A total of 7438 surplus embryos after embryo transfer or Vitrification were collected and formed 1382 high-quality blastulas(18.58%) af ter the sequential culture.At D3 cleavage stage,6-cell embryo had the significantly higher rate of high-quality blastula formation(10.34%) than 4 or 5-cell embryo(5.45%)(P=0.011);7-9cells embryo had the significantly higher rate of high-quality blastula formation(19.95%)than 6-cell embryo,≥10-cell embryo had the significantly higher rate of high-quality blastula formation(27.47%)than 7~ 9-cell embryo(P0.001).At D2 cleavage stage,4-cell embryo had the significantly higher rate of high-quality blastula formation(25.40%)than 3 or 5-cell embryo(10.26%,15.41%)(P0.001).At D2/ D3 cleavage stage,the embryo with I-IIgrade fragment had the significantly higher rate of high-quality blastula formation than the embryo with III-IV grade fragment(P0.001).Conclusion In-vitro blastocyst culture can have significant advantage to screen the high-quality embryo with development potential.The blastocyst formation has close relationship with D2/D3 embryo blastomere number and fragment.