1. Department of Obstetrics and Gynecology, Xiantao Maternal and Child Health Hospital, Xiantao, Hubei 433000, P.R. China
2. Department of Obstetrics and Gynecology, Maternity Hospital of Diarete Province, Diarete, Diarete 14000, Algeria
3. Department of Obstetrics and Gynecology, Zaoyang First People's Hospital, Zaoyang, Hubei 441200, P.R. China
4. Department of Obstetrics and Gynecology, Xiangyang Central Center Hospital, Xiangyang, Hubei 441000, P.R. China