1. Department of Obstetrics and Gynecology, Graduate School of Medicine, Nagoya University, Nagoya 466‑8550, Japan
2. Department of Healthcare Administration, Graduate School of Medicine, Nagoya University, Nagoya 466‑8550, Japan
3. Department of Obstetrics and Gynecology, Banbuntane Hotokukai Hospital, Fujita Health University, Nagoya 454-8509, Japan