[1] Sichuan Univ, West China Univ Hosp 2, Dept Obstet & Gynecol, Chengdu, Peoples R China
[2] Sichuan Univ, Key Lab Birth Defects & Related Dis Women & Childr, Minist Educ, Chengdu, Peoples R China
[3] Zhejiang Univ, Affiliated Hosp 4, Dept Obstet & Gynecol, Sch Med, Yiwu, Peoples R China
[4] Sichuan Univ, West China Univ Hosp 2, 20,Sect 3,Renmin South Rd, Chengdu 610041, Sichuan, Peoples R China