1. Department of Obstetrics and Gynecology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, PR China
2. Department of Obstetrics and Gynecology, Chongqing Yubei District Maternal and Child Health Care Hospital, Chongqing, PR China
3. State Key Laboratory of Ultrasound in Medicine and Engineering, Chongqing Key Laboratory of Ultrasound in Medicine and Engineering, College of Biomedical Engineering, Chongqing Medical University, Chongqing, PR China
4. Department of Obstetrics and Gynecology of Chongqing, Nanchuan People’s Hospital, Chongqing, PR China