1. Taizhou Hospital of Zhejiang Province affiliated to Wenzhou Medical University, Luqiao, Zhejiang 318050, China
2. Wuhan Economic Development Zone (Hannan) People's Hospital, The department of obstetrics and gynecology, Wuhan, Hubei 430090, China
3. Gaochun people's Hospital of Nanjing City, The department of obstetrics and gynecology, Nanjing, Jiangsu 211302, China