1. Department of Ultrasound, Jiaojiang Maternal and Child Health Hospital, Taizhou, China
2. Department of Gynecology, Changxing People’s Hospital of Chongming District, Shanghai, China
3. Department of gynaecology, Lishui Hospital of Traditional Chinese Medicine, Lishui, China
4. Department of Gynecology, Huzhou Maternity & Child Health Care Hospital, Huzhou, China
5. Department of obstetrics and gynecology, Hospital Affiliated to Zhejiang Chinese Medical University, Hangzhou, China
6. Department of Gynecology, Jiaojiang Maternal and Child Health Hospital, Taizhou, China