1. Obstetrics and Gynecology Department, Hangzhou First People's Hospital, Hangzhou, Zhejiang 310006, PR China
2. Obstetrics and Gynecology Department, The First Affiliated Hospital of Zhejiang Chinese Medical University Zhejiang Provincial Hospital of TCM, Hangzhou, Zhejiang 310016, PR China
3. Department of Obstetrics and Gynecology, Central Hospital of Wenzhou, Luchengqu, Wenzhou, Zhejiang 325000, PR China