1. 2nd Department of Obstetrics and Gynaecology, Faculty of MedicineAristotle University of Thessaloniki Thessaloniki Greece
2. Harvard TH Chan School of Public Health, Department of Epidemiology Boston MA USA
3. 1st Department of Neonatology, School of MedicineAristotle University of Thessaloniki Thessaloniki Greece
4. Department of Obstetrics and GynaecologyUniversity of Ioannina Medical School Ioannina Greece