1. Department of Obstetrics and Gynecology and Division of Neonatology; Policlinico Abano Terme; Abano Terme; Italy
2. Division of Social Statistics and Demography; University of Southampton; Southampton; UK
3. Department of Pediatrics; Padua University School of Medicine; Padua; Italy
4. Department of Obstetrics and Gynecology; Catholic University of the Sacred Heart; Rome; Italy