Authors
Petya P. Chaveeva
Department of Fetal Medicine, Specialized Hospital for Active Treatment of Obstetrics and Gynecology “Dr. Shterev”, Sofia, Bulgaria
Slavcho T. Tomov
Department of Midwifery, Medical University – Pleven, Bulgaria
Atanas D. Shterev
Department of Fetal Medicine, Specialized Hospital for Active Treatment of Obstetrics and Gynecology “Dr. Shterev”, Sofia, Bulgaria