1. Department of Obstetrics and Gynecology, Chengdu Wenjiang Jingliang Hospital, Chengdu, China
2. School of Clinical Medicine, The First Affiliated Hospital of Henan University of Science and Technology, Luoyang, China
3. Department of Obstetrics and Gynecology, The Seventh Affiliated Hospital of Xinjiang Medical University, Urumqi, China
4. Department of Obstetrics and Gynecology, Shanghai East Hospital, School of Medicine, Tongji University, Shanghai, China