[1] Xi An Jiao Tong Univ, Sch Publ Hlth, Xian 710061, Shaanxi, Peoples R China
[2] Shaanxi SANZ Pharmaceut Co Ltd, Xian 710086, Shaanxi, Peoples R China
[3] CAMS & PUMC, PUMC Hosp, Dept Obstet & Gynecol, Natl Clin Res Ctr Obstet & Gynecol Dis, Beijing, Peoples R China
[4] Northwest Womens & Childrens Hosp, Xian 710061, Shaanxi, Peoples R China
[5] Pingyao Agr & Rural Bur, Pingyao 031100, Shanxi, Peoples R China
[6] Maternal & Child Hlth Care Hosp HaiDian Dist, Nutr Dept, Beijing 100000, Peoples R China
[7] Shaanxi Univ Chinese Med, Sch Publ Hlth, Xianyang 712046, Peoples R China
[8] Zhengzhou Univ, Affiliated Hosp 2, Dept Adv Med Res, Jingba Rd, Zhengzhou 450014, Peoples R China