1. Department of Gynecology and Obstetrics, Graduate School of Medicine and Faculty of Medicine, Kyoto University, Kyoto, Japan.
2. Department of Obstetrics and Gynecology, Hokkaido University School of Medicine, Sapporo, Japan.
3. Section of Clinical Epidemiology, Department of Community Medicine, Kyoto University, Kyoto, Japan.
4. Department of Health Policy and Management, Johns Hopkins Bloomberg School of Public Health (JHSPH), Baltimore, Maryland, USA.
5. Biometrics Department, Chugai Pharmaceutical Co., Ltd., Tokyo, Japan.
6. Medical Science Department, Chugai Pharmaceutical Co., Ltd., Tokyo, Japan.
7. Department of Obstetrics and Gynecology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.