Figure 2. The hierarchical model with five splits used to generate the KIDScore D3 Basic, adapted from Petersen et al., 2016. Number of inputted embryos, distribution of embryos into KIDScore classes, and corresponding live birth rates (LBR) are shown in the figure. The embryos are ranked based on i) initial cleavage speed up to three cells, ii) t3 time point, ,iii and iiii) irregular cell divisions from 2 cells to 5 cells as described by the (t5-t3)/(t5-t2) equation, and iiiii) on reaching eight cells before 66 hours post insemination (HPI). KID4 embryos are composed of two types of embryos: those that have irregular divisions and those that do not reach eight cells prior to 66 HPI.