In a study of preterm newborns that weighed under 1251 g in the United States, the mean IGF-1 value at 28–33 weeks of corrected GA without ROP was 20.0 ng/mL, and, at Stage 1 or 2, the ROP was 18.0 ng/mL, and, at Stage 3, the ROP was 17.0 ng/mL, which suggests that the IGF-1 values were associated with the ROP development and severity [30]. Here, IGF1 is linked to retinopathy of prematurity.