1 Department of Obstetrics and Gynecology, Kuo General Hospital, Taipei, Tainan, Taiwan. Electronic address: drgynobs@yahoo.com.tw.
2 Department of Obstetrics and Gynecology, Cardinal Tien Hospital-Hsintien, New Taipei City, Taiwan; Department of Obstetrics and Gynecology, Fu Jen Catholic University, New Taipei City, Taiwan.