Our significant effect of embryo size on the gene expression profile is consistent with Barnwell et al. (2016) who transferred grade-1 and grade-3 embryos (compact morulas) on Day 6.5 and found that 348 genes were differentially expressed between conceptuses classified as short (4.2 mm) or long (24.7 mm) at Day 15 of gestation (n = 5 embryos per group). However, Barnwell et al. (2016) found no differences in the Day 15 gene expression profiles between grade-1 and grade-3 embryos, although grade-3 embryos were less likely to survive to Day 15.