1. Department of Obstetrics, Yantaishan Hospital, Yantai 264000, China
2. Department of Clinical Laboratory, Zhangqiu District People’s Hospital, Jinan 250200, China
3. ICU, The Affiliated Qingdao Central Hospital of Qingdao University, The Second Affiliated Hospital of Medical College of Qingdao University, Qingdao 266042, China
4. Department of Gynaecology, Zhangqiu District Maternity and Child Care Hospital, Jinan 250200, China
5. Medical Laboratory and Diagnostic Center, Jinan Central Hospital, Jinan 250013, China