1 Inner Mongolia Medical University, Department of Obstetrics and Gynecology, Affiliated Hospital of Inner Mongolia Medical University, Hohhot North Street, Inner Mongolia 010050, China.
2 Inner Mongolia Medical University, Department of Obstetrics and Gynecology, Affiliated Hospital of Inner Mongolia Medical University, Hohhot North Street, Inner Mongolia 010050, China. Electronic address: sjd123@163.com.
3 Inner Mongolia Medical University, Department of Orthopedics, Affiliated Hospital of Inner Mongolia Medical University, Hohhot North Street, Inner Mongolia 010050, China.