[1] Xi An Jiao Tong Univ, Affiliated Hosp 1, Dept Gynecol & Obstet, Xian 710061, Shaanxi, Peoples R China
[2] Northwest Women & Children Hosp, Dept Gynecol 2, Xian 710061, Shaanxi, Peoples R China
[3] Xian Med Univ, Affiliated Hosp 1, Dept Gynecol & Obstet, Xian 710077, Shaanxi, Peoples R China