Preterm infants often show a period of very low circulating IGF-1 levels and small-scale clinical studies have tested the effects of low-dose physiologic IGF-1 supplementation with inconclusive effects on ROP, IVH, and NEC outcomes, but with consistent preventative effects on BPD.27,28,45 As many diseases of prematurity associate with systemic immune dysfunctions and inflammation, it is critical to better understand how circulating IGF-1 levels may or may not be directly related to immune development. This evidence concerns the gene IGF1 and necrotizing enterocolitis.