1. Department of Obstetrics and Gynecology, Keio University School of Medicine, Tokyo, Japan
2. Perinatology Committee of the Japan Society of Obstetrics and Gynecology, Kanagawa, Japan
3. Department of Obstetrics and Gynecology, Faculty of Medicine, Juntendo University, Tokyo, Japan
4. Biostatistics at Clinical Translational Research Center, Keio University School of Medicine, Tokyo, Japan
5. School of Data Science, Yokohama City University, Kanagawa, Japan
6. Department of Gynecology and Obstetrics, Kyoto University, Kyoto, Japan
7. Department of Obstetrics and Gynecology, Faculty of Medicine, Mie University, Mie, Japan
8. Department of Obstetrics and Gynecology, University of Tsukuba, Ibaraki, Japan
9. Department of Obstetrics and Gynecology, Toho University Medical Center Ohashi Hospital, Tokyo, Japan
10. Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, Shizuoka, Japan