[1] Cent South Univ, Xiangya Hosp 2, Dept Gynecol & Obstet, Changsha 410011, Hunan, Peoples R China
[2] Cent South Univ, Xiangya Hosp 2, Dept Ultrasound Diag, Changsha 410011, Hunan, Peoples R China
[3] Hunan Univ Tradit Chinese Med, Ningxiang Hosp, Dept Gynecol & Obstet, Ningxiang 410600, Hunan, Peoples R China
[4] Yuanjiang Maternal & Child Hlth Care Hosp, Dept Gynecol & Obstet, Yuanjiang 413100, Hunan, Peoples R China
[5] Xiangnan Univ, Affiliated Hosp, Dept Gynecol & Obstet, Chenzhou 423000, Hunan, Peoples R China