The present invention relates to methods for maturing the mucosal defense and rebalancing the immune system preventing a cytokine storm； treatment or prevention of neonatal sepsis, necrotizing enterocolitis, acute and prolonged diarrhea, short bowel syndrome, respiratory illness, respiratory infection, respiratory failure, impaired neurodevelopment and extra uterine growth restriction, the method comprising oral and/or intrapulmonary and/or subcutaneous administration of at least one antimicrobial peptide selected from the group consisting of α-defensins, β-defensins, cathelicidins, lactoferrins/lactoferricins and lysozymes and/or GLP-2 or GLP-2 analogs in a preterm infant or a mother about to give birth to a preterm infant.
