1. Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital; Department of Physical Medicine and Rehabilitation, Cheng Hsin Medical Center; Institute of Epidemiology, College of Public Health, National Taiwan University, Taipei, Taiwan
2. Department of Obstetrics and Gynecology, Chang Gung Memorinal Hospital, 199 Dun-hua North Rd, Taipei 105, Taiwan; Department of Physical Medicine and Rehabilitation, Cheng Hsin Medical Center; Institute of Epidemiology, College of Public Health, National Taiwan University, Taipei, Taiwan;