EPO and retinopathy of prematurity: High levels of VEGF-R1, IL-8, MMP-9, EPO, TNF-α and bFGF are related to a risk factor for prethreshold ROP in the first three postnatal weeks. On Day 28, elevated concentrations of IL-6, TNF-α, TNF-R1/-R2, IL-8 are still related to the risk (48).