1 Department of Obstetrics and Gynecology, The First Hospital of Jilin University, 1 Xinmin Road, Changchun, 130000, Jilin, China.
2 Department of Obstetrics and Gynecology, The First Hospital of Jilin University, 1 Xinmin Road, Changchun, 130000, Jilin, China. Electronic address: hejin@jlu.edu.cn.