1. Department of Obstetrics and gynecology, The Second Hospital of Jinlin Univsity, Changchun, China
2. Emergency Department, The Affiliated Hospital to Changchun University of Chinese Medicine, Changchun, China
3. Department of Pathology, The First Hospital of Jilin University, Changchun, China
4. Department of Electrical diagnosis, Jilin Maternal and Child Health Hospital, Changchun, China