Relationships between timing of syngamy, female age and implantation potential in human in vitro-fertilised oocytes

Abstract

Although early developmental markers are frequently used to select embryos for transfer in human assisted reproduction, their value as independent predictors of outcome is often unclear. In this study, the value of using early syngamy and first cleavage as predictors of implantation potential of Day 2 embryos was investigated by examining their interrelationships with subsequent development, female age and implantation. Implantation rates were higher when syngamy occurred before 23-24 h post insemination even when all embryos analysed were transferred 42 h post insemination at the 4-cell stage (25.8 v. 11.9% for the later syngamy group; P < 0.01). Although there was a significant (r = 0.682;..