[1] Southern Med Univ, Nanfang Hosp, Dept Obstet & Gynecol, Guangzhou 510000, Guangdong, Peoples R China
[2] Jiangmen Cent Hosp, Dept Gynecol, Jiangmen 529030, Guangdong, Peoples R China
[3] Liaoning Canc Hosp, Dept Gynecol, Shenyang 110801, Liaoning, Peoples R China
[4] China Med Univ, Hosp 1, Dept Gynecol, Shenyang 110001, Liaoning, Peoples R China
[5] Foshan Women & Children Hosp, Dept Obstet & Gynecol, Foshan 528099, Guangdong, Peoples R China
[6] Airforce Med Univ, Xijing Hosp, Dept Obstet & Gynecol, Xian 710032, Shaanxi, Peoples R China
[7] Qingdao Univ, Dept Gynecol, Affiliated Hosp, Qingdao 266003, Shandong, Peoples R China
[8] Beijing Hosp, Dept Obstet & Gynecol, Beijing 100730, Peoples R China
[9] Gansu Prov Hosp, Dept Obstet & Gynecol, Lanzhou 730020, Gansu, Peoples R China
[10] Guangzhou Med Univ, Coll Publ Hlth, Dept Epidemiol, Guangzhou 511495, Guangdong, Peoples R China
[11] Peking Union Med Coll Hosp, Peking Union Med Coll, Dept Obstet & Gynecol, Beijing 100005, Peoples R China