Ming-Cheh Ou1, Dennis Ou2, Chung-Chu Pang3. 1. Department of Obstetrics and Gynecology, Taipei City Hospital, Taipei City, Taiwan; Department of Obstetrics and Gynecology, Taipei Medical University, Taipei City, Taiwan. Electronic address: mcou@ym.edu.tw. 2. Department of Mechanical Engineering and Biomedical Engineering, Carnegie Mellon University, Pittsburgh, PA, USA. 3. Department of Obstetrics and Gynecology, Su Women Hospital, Taipei City, Taiwan.