DECR1 and fetal growth restriction: The mean DNAm differences in IUGR (also known as delta beta or Δβ) across all twin pairs for the DECR1 was 17.5 % (bump hunting p = 0.0027), reaching as high as 22.5 and 21.4 %, respectively, for the top two differentially methylated CpG sites within the DMR.