1 The Recurrence Prevention Committee, Japan Obstetric Compensation System for Cerebral Palsy, Japan Council for Quality Health Care, Tokyo, Japan; Department of Obstetrics and Gynecology, Mie University Graduate School of Medicine, Mie, Japan; Department of Obstetrics and Gynecology, Sakakibara Heart Institute, Tokyo, Japan. Electronic address: hiro.nakao1987@gmail.com.
2 The Recurrence Prevention Committee, Japan Obstetric Compensation System for Cerebral Palsy, Japan Council for Quality Health Care, Tokyo, Japan; Kugayama Hospital, Tokyo, Japan.
3 The Recurrence Prevention Committee, Japan Obstetric Compensation System for Cerebral Palsy, Japan Council for Quality Health Care, Tokyo, Japan; Department of Obstetrics and Gynecology, Mie University Graduate School of Medicine, Mie, Japan.