1. Department of Perinatology and Gynecology; Kagawa University Graduate School of Medicine; Miki Kagawa Japan
2. Department of Obstetrics and Gynecology; Yashima General Hospital; Yashima Nishimachi Takamatsu, Kagawa Japan
3. Department of Obstetrics and Gynecology, Institute of Health Biosciences; The University of Tokushima Graduate School; Tokushima Japan