A novel embryo quality scoring system to compare groups of embryos at different developmental stages.

Purpose: To construct a new embryonic quality scoring system to compare groups of embryos at different developmental stages.

Methods: Based on a hypothesis that the implantation potential of any embryo in an ovum pickup (OPU) cycle remains the same at any stage of development, be it day 2, 3, or 5, a new embryo quality scoring (EQS) system was designed. It was based on the analysis of the clinical results of 1610 single embryo transfers. We validated this scoring system in the comparison of embryonic quality between groups by evaluating the mean scores calculated at day 2, day 3, and day 5 for 957 embryos (150 cycles) from 3 different groups. We then compared EQSs of patients with pregnancy favorable factors (group A) such as young age and high AMH levels, with the patients with contra features (group B).

Results: We confirmed that each mean EQS assessed at different stages of embryonic development within the same group was similar. The mean EQSs on day 3 and day 5 in group A were significantly higher than the mean EQSs on days 2, 3, and 5 in group B.

Conclusion: The novel EQS system proposed by us enables embryonic quality comparison between groups of embryos at different developmental stages.