1. Neonatal Intensive Care Unit; Department of Woman's and Child's Health; Azienda Ospedaliera-University of Padova; Padova; Italy
2. Neonatal Intensive Care Unit; Azienda Ospedaliero-Universitaria-Policlinico di Modena; Modena; Italy
3. Department of Statistical Science; University of Padua; Padua; Italy
4. Neonatal Intensive Care Unit; Valduce Hospital; Como; Italy
5. Neonatal Intensive Care Unit; San Gerardo Hospital; Monza; Italy
6. Neonatal Intensive Care Unit; San Filippo Neri Hospital; Roma; Italy
7. Unit of Epidemiology; Bambino Gesù Pediatric Hospital; Roma; Italy
8. Neonatal Intensive Care Unit; Infermi‘s Hospital, Rimini; Italy