1. Department of Obstetrics, Gynecology and Family Medicine; School of Medicine, Hamamatsu University; Hamamatsu Shizuoka Japan
2. Department of Obstetrics and Gynecology; Juzen Kinen Hospital; Hamamatsu Shizuoka Japan
3. Department of Obstetrics and Gynecology; Kikugawa Municipal General Hospital; Shizuoka Japan