1 Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, Keelung, Taiwan.
2 Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, Keelung, Taiwan; Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, Taipei, Taiwan; Department of Medicine, College of Medicine, Chang Gung University, Taoyuan, Taiwan. Electronic address: thh20@cgmh.org.tw.