1. Department of Obstetrics and Gynecology, Red Cross Fukui Hospital, Fukui 918-8501, Japan
2. Department of Obstetrics and Gynecology, Faculty of Medical Sciences, University of Fukui, Fukui 910-1193, Japan
3. Department of Obstetrics and Gynecology, Fukui-Ken Saiseikai Hospital, Fukui 918-8503, Japan
4. Department of Obstetrics and Gynecology, Tannan Regional Medical Center, Fukui 916-8515, Japan