It is postulated that exposure of the preterm brain to inflammatory mediators during infectious episodes contribute to brain (white matter) injury and poor developmental outcome. It has been demonstrated that breast milk has a beneficial effect on neurodevelopment outcomes in preterm infants. The investigators hypothesize that lactoferrin is the major factor in milk responsible for this effect due to its antimicrobial and immunomodulatory properties: it reduces inflammation by decreasing production of tumor necrosis factor α and other pro-inflammatory molecules, and by regulating the immune response, protecting against severe inflammation related to infection and septic shock. In addition, the investigators hypothesize that lactoferrin will improve growth by decreasing the frequency of growth-impairing infections and by lactoferrin effect on intestinal cell proliferation, differentiation and maturation.