Sa Ra Lee1, Soo Yeon Park2, Mi Hye Park2. 1. Department of Obstetrics and Gynecology, Ewha Womans University, School of Medicine, Seoul, Republic of Korea. Electronic address: sarahmd@ewha.ac.kr. 2. Department of Obstetrics and Gynecology, Ewha Womans University, School of Medicine, Seoul, Republic of Korea.