1. Faculty of Medicine, University of Belgrade, Dr Subotica 8, 11000 Belgrade, Serbia
2. Department of High-Risk Pregnancies, University Clinic for Gynecology and Obstetrics “Narodni Front”, Kraljice Natalije 62, 11000 Belgrade, Serbia
3. Department of Obstetrics and Gynecology, Faculty of Medicine University of Novi Sad, Branimira Ćosića 37, 21000 Novi Sad, Serbia