1 Department of Obstetrics and Gynecology, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abenoku, Osaka, Japan.
2 Department of Obstetrics and Gynecology, Osaka City University Graduate School of Medicine, 1-4-3 Asahimachi, Abenoku, Osaka, Japan. dtachibana@med.osaka-cu.ac.jp.