1 Department of Obstetrics and Gynecology, Saitama Medical Center, Jichi Medical University School of Medicine, Saitama (Drs. Chikazawa, Imai, Ito, Kuwata, and Konno). Electronic address: kendokenro@hotmail.com.
2 Department of Obstetrics and Gynecology, Saitama Medical Center, Jichi Medical University School of Medicine, Saitama (Drs. Chikazawa, Imai, Ito, Kuwata, and Konno).
3 Department of Obstetrics and Gynecology, Keio University, Tokyo (Dr. Hayashi), Japan.