IGF1 and retinopathy of prematurity: Only studies investigating serum biomarker levels in preterm infants (<37 weeks gestation) were included.<h4>Results</h4>Meta-analysis suggests that low serum IGF-1 levels have a strong association with the development of ROP [SMD (95% CI) of -.46 [-.63, -.30], <i>p</i> < .001].