IGF signalling (specifically IGF-2, IGFBP-1, and IGF-1R) plays a critical role in trophoblast invasion and increased utero–placental blood flow during implantation, while imbalances or abnormalities in this signalling lead to adverse pregnancy outcomes, and have been associated with IUGR [170]. The gene discussed is IGFBP1; the disease is fetal growth restriction.