Embryo Division Timings and Morphikinetic Top-quality Embryo Rates Derived from GnRH-antagonist ICIS Cycles Triggered by Either hCG, GnRH-agonist or Dual Trigger

Time lapse allows embryo quality assessment by documenting timing of events and length of intervals in embryo development, providing a more objective scoring of the embryos for embryo selection.We sought to evaluate if the rate of optimal timed top-quality embryos is influenced by the type of triggering in GnRH-antagonist ICSI cycles triggered by hCG (Ovitrelle 250mcg), GnRH-agonist (Decapaptyl 0.2MG) and dual trigger (co- administration of GnRH-agonist and hCG) between July 2013 - December 2020. Top- quality embryos with the highest chance to implant were defined: tPNf <24.08, t2<26.6, S2<0.9 and t8<56 hours post insemination (hPi) for cleavage embryos and t2<26.6, S2<0.9, t8<56 and tSB<96.6 hPi for blastocysts. Multivariate logistic regression analysis age, type of gonadotrophins, number of oocytes aspirated and peak estradiol levels was performed. We analyzed 3,352 embryos derived from 1162 GnRH-antagonist ICSI cycles; 2,169 embryos in the hCG trigger group, 737 embryos in the GnRH-agonist group and 446 embryos in the Dual trigger group. Division timing durations (tPB2, tPNf, t2-t7) were significantly shorter in the GnRH-agonist group compared to the other groups. The highest top quality cleavage embryo rate was with GnRH-agonist trigger compared to hCG and Dual trigger (21.6% versus 12.7% and 20.2% respectively, p< 0.001). Pregnancy rates were similar between the groups. In the multivariate regression model assessing cell cycle divisions parameters and top quality cleavage rates; the type of trigger remained a significant factor after controlling for age, type of gonadotrophins, number of oocytes aspirated and peak estradiol levels.