Serena Xodo1, Luigi Xodo2, Vincenzo Berghella3. 1. Department of Gynecology and Obstetrics, School of Medicine, University of Udine, Udine, Italy. 2. Department of Medical and Biological Sciences, School of Medicine, University of Udine, Udine, Italy. 3. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, Sidney Kimmel Medical College of Thomas Jefferson University, Philadelphia, Pennsylvania.