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