[1] Hebei Med Univ, Dept Obstet & Gynecol, Hosp 2, Shijiazhuang 050000, Hebei, Peoples R China
[2] Capital Med Univ, Beijing Obstet & Gynecol Hosp, Dept Gynecol Endocrinol, Beijing 100026, Peoples R China
[3] Shandong First Med Univ & Shandong Acad Med Sci, Dept Gynecol Oncol, Shandong Canc Hosp & Inst, Jinan 250021, Shandong, Peoples R China
[4] Zhengzhou Univ, Affiliated Hosp 1, Dept Obstet & Gynecol, Zhengzhou 450000, Henan, Peoples R China