IGF1 and fetal growth restriction: According to an animal model of intrauterine growth restriction induced by maternal nutritional restriction (also known as another BPD model), IGF-1 expression is decreased, and intrinsic-pulmonary IGF-I signaling is suppressed during the fetal and early neonatal periods; however, during the later catch-up growth phase, both IGF-I and IGF-I signaling are elevated, and septal thickness, matrix deposition, and increased expression of vimentin and collagen Iα1 are observed due to the activation of myofibroblasts50.