Low blastocyst formation rates in day-2 fertilized oocytes

Purpose: To examine the blastocyst formation rates of day-2 fertilized oocy tes. Methods: A retrospective study of the outcomes/blastocyst formation of day- 2 fertilized oocytes was undertaken. Results: Fertilization rates of day-1 and -2 oocytes by intra-cytoplasmic s perm injection were similar: The development frequencies to four cells were similar However the blastulation rates were significantly lower from the d ay-2 fertilized eggs. The fertilization rates from day-2 conventional in vi tro fertilization reinsemination were lower than the fertilization rates of day-1 oocytes. The blastulation rates from day-2 fertilized eggs were also lower than the rates from day-1 fertilized eggs in the in vitro fertilizat ion group. Conclusions: Fertilization is nor a goad indicator to predict the viability of fertilized oocytes. Day-2 fertilized oocytes had significantly lower bl astocyst formation races than the rates from day-1 fertilized oocytes.