1. Obstetrical Department, Maternal and Child Health Care of Zaozhuang, Zaozhuang, China
2. Department of Blood Transfusion, The Affiliated Hospital of Qingdao University, Qingdao, China
3. Biology Department, The Medical College of Qingdao University, Qingdao, China
4. Department of Clinical Laboratory, Chongqing Health for Women and Children, Chongqing, China
5. Department of Clinical Laboratory, Qingdao Municipal Hospital (Group), Qingdao, China
6. Prenatal Diagnosis Center, The Affiliated Hospital of Qingdao University, Qingdao, China