1. Department of Endocrinology, Hematology and Gerontology, Chiba University Graduate School of Medicine, Chiba, Japan
2. Department of Obstetrics and Gynecology, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan
3. Obstetrics and gynecology, International University of Health and Welfare School of Medicine, Narita, Chiba, Japan