1. Neonatal Intensive Care Unit, “San Giovanni Calibita Fatebenefratelli” Hospital, Isola Tiberina, Rome, Italy
2. Neonatology Unit, Department of Woman and Child Health and Public Health, Fondazione Policlinico Universitario “Agostino Gemelli” IRCCS, Rome, Italy
3. Dipartimento di Scienze della Vita e Sanità Pubblica, Facoltà di Medicina e Chirurgia, Università Cattolica del Sacro Cuore, Rome, Italy
4. Neonatal Intensive Care Unit, Medical and Surgical Department of Fetus, Newborn and Infant, “Bambino Gesù” Children's Hospital IRCCS, Rome, Italy
5. Section of Hygiene, Institute of Public Health, Università Cattolica del Sacro Cuore, Rome, Italy
6. Division of Neonatology, Erasmus MC-Sophia Children's Hospital, Rotterdam, The Netherlands