[1] Sichuan Univ, West China Univ Hosp 2, Dept Obstet & Gynecol, Chengdu, Peoples R China
[2] Sichuan Univ, Minist Educ, Key Lab Birth Defects & Related Dis Women & Childr, Chengdu, Peoples R China
[3] Sichuan Univ, West China Hosp 2, Dept Gynecol & Obstet, 3 Sect People South St, Chengdu 610041, Peoples R China