1. Center for Laboratory Diagnosis, Yantai Yuhuangding Hospital Affiliated to Medical College of Qingdao University, Yantai, Shandong, P.R. China
2. Department of Obstetrics, Yantai Yuhuangding Hospital Affiliated to Medical College of Qingdao University, Yantai, Shandong, P.R. China
3. Department of Gynaecology, Yantai Yuhuangding Hospital Affiliated to Medical College of Qingdao University, Yantai, Shandong, P.R. China