IGF1 and bronchopulmonary dysplasia: It has also been reported that low serum IGF-1 levels were strongly associated with various neonatal complications in animal models (periventricular leukomalacia model rat; cerebral hypoxic ischemia model rat; primary IGF-1-deficient mice; and a necrotizing enterocolitis model) [31,32,33,34] and humans (poor weight gain and brain weight, and the development of ROP and bronchopulmonary dysplasia) [7,9,10,11].