1. Department of Clinical Laboratory, Women and Children's Hospital of Chongqing Medical University, Chongqing Health Center for Women and Children, Chongqing 401174, P.R. China
2. Department of Obstetrics and Gynecology, Women and Children's Hospital of Chongqing Medical University, Chongqing Health Center for Women and Children, Chongqing 401174, P.R. China