Insulin-like growth factor 1 (IGF-1) is the main mediator of fetal growth. An association has been described between low levels of IGF-1 and the development of some morbidities such as bronchopulmonary dysplasia (BPD) and retinopathy of prematurity (ROP) in newborns weighing less than 1500 grams or less than 32 weeks at birth. Objective: To determine the association between serum levels of IGF-1 and morbidity in premature infants. Patients and Method: prospective observational study in 40 newborns. Serum levels of IGF-1 were measured at 24 hours and 15, 30, and 45 postnatal days. Pathologies such as BPD, ROP, intraventricular hemorrhage (IVH), and other neonatal morbidities and their association with serum IGF-1 levels were identified. Results: The mean gestational age and birth weight of the newborns were 28.7 weeks (range 24-32) and 1248 grams (range 680-2100), respectively. There was an association between low IGF-1 levels and BPD at 15 and 30 days (p = 0.035 and 0.018); with late sepsis at 15 and 30 days (p = 0.038 and 0.010), and with hemodynamically significant patent ductus arteriosus (hs-PDA) at 30 days (p = 0.03). No association of low IGF-1 levels with other pathologies was found. Conclusion: There was an association between low postnatal IGF-1 levels and BPD, late sepsis, and hs-PDA. New prospective studies are required to corroborate these results and the association between low IGF-1 levels and other neonatal morbidities.