1. Department of Obstetrics and Gynecology, The First Affiliated Hospital of Soochow University, Suzhou, China.
2. Department of Obstetrics and Gynecology, The People's Hospital of Suzhou National New & Hi-Tech Development Zone, Suzhou, China.
3. Department of Obstetrics and Gynecology, Taixing People's Hospital, Taizhou, China.