1. Department of Clinical Laboratory, Yantaishan Hospital, Yantai 26400, China
2. Department of Obstetrics, The Third People’s Hospital of Qingdao, Qingdao 266041, China
3. ICU, Affiliated Qingdao Central Hospital, Qingdao University, Qingdao 266000, China
4. Department of Gynaecology, People’s Hospital of Huakang, Rizhao 276800, China
5. Department of Obstetrics, Zhangqiu District People’s Hospital, Jinan 250200, China