1. Clinical Epidemiology Unit, University Hospital “P. Giaccone”, 90127 Palermo, Italy
2. Neonatology and Neonatal Intensive Care Unit, Ingrassia Hospital, 90132 Palermo, Italy
3. Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties “G. D’Alessandro”, University of Palermo, 90127 Palermo, Italy
4. Neonatology and Neonatal Intensive Care Unit, University Hospital “P. Giaccone”, 90127 Palermo, Italy
5. Neonatology and Neonatal Intensive Care Unit, Villa Sofia Cervello Hospitals, 90146 Palermo, Italy