1. Division of Obstetrics and Gynaecology, Department of Maternal, Neonatal and Infant Health ASL Biella Biella Italy
2. Department of Obstetrics and Gynaecology AOUI Verona, University of Verona Verona Italy
3. Department Obstetrics and Gynecology Women's Health Institute, Cleveland Clinic Cleveland OH USA
4. Department of Obstetrics and Gynaecology F. Del Ponte Hospital, University of Insubria Varese Italy