1. Department of Reproduction, The Affiliated Changzhou Maternity and Child Health Care Hospital of Nanjing Medical University, Changzhou, PR China
2. Department of Gynaecology and Obstetrics, Wuxi People’s Hospital affiliated to Nanjing Medical University, Wuxi, PR China
3. Department of Obstetrics, The Affiliated Wuxi Maternity and Child Health Care Hospital of Nanjing Medical University, Wuxi, PR China
4. Department of Obstetrics, Nanjing Maternity and Child Health Care Hospital, Women’s Hospital of Nanjing Medical University, Nanjing, PR China
5. Nanjing Maternity and Child Health Care Institute, Nanjing Maternity and Child Health Care Hospital, Women’s Hospital of Nanjing Medical University, Nanjing, PR China