IGF1 and fetal growth restriction: In humans, inactivation mutations in the IGF-1 gene are associated with growth restriction [25,37], and all mutations in the IGF-1R gene identified so far are associated with severe IUGR (length deficit of −0.3 to −5.8 standard deviation score (SDS) depending on the specific mutation) and short stature [25,33,38,39,40,41,42,43,44].