1. Jiaxing Maternity and Child Health Care Hospital, Jiaxing, Zhejiang, China;
2. Department of Obstetrics and Gynecology, College of Medicine, Jiaxing University, Jiaxing, Zhejiang ,China;
3. Department of Obstetrics and Gynecology, The Affiliated Changzhou NO. 2 People’s Hospital with Nanjing Medical University, Changzhou, Jiangsu, China