1. Department of Obstetrics and Gynecology, Sakakibara Heart Institute, Tokyo, Japan
2. Department of Obstetrics and Gynecology, Mie University School of Medicine, Mie, Japan
3. Department of Obstetrics and Gynecology, St. Marianna University School of Medicine, Kanagawa, Japan
4. Department of Obstetrics and Gynecology, Showa University School of Medicine, Tokyo, Japan
5. Department of Obstetrics and Gynecology, Hamamatsu University School of Medicine, Hamamatsu, Japan
6. Department of Obstetrics and Gynecology, Toho University, Tokyo, Japan
7. Division of Perinatology, Maternal and Perinatal Care Center, Seirei Hamamatsu General Hospital, Hamamatsu, Japan
8. Department of Perinatology and Gynecology, National Cerebral Cardiovascular Center, Osaka, Japan
9. Department of Obstetrics and Gynecology, Sagamihara National Hospital, Kanagawa, Japan
10. Ishiwata Obstetrics and Gynecology Hospital, Ibaraki, Japan
11. Department of Neurosurgery, National Cerebral and Cardiovascular Center, Osaka, Japan