IGF1 and fetal growth restriction: Another study of methylation (performed on cord blood and placenta) restricted to growth-related genes found no association between intrauterine growth retardation and IUGR and the methylation of CpGs at the IGF1, IGF2, and INS loci (note that this study investigated only 3 CpGs located within the IGF1 P1 promoter) [24].