[1] Peking Univ, Sch Publ Hlth, Dept Nutr & Food Hyg, 38 Xue Yuan Rd, Beijing 100191, Peoples R China
[2] Capital Med Univ, Beijing Childrens Hosp, Natl Ctr Childrens Hlth, Dept Sci Res, Beijing 100045, Peoples R China
[3] Peking Univ, Sch Nursing, 38 Xue Yuan Rd, Beijing 100191, Peoples R China
[4] Shijiazhuang Obstet & Gynecol Hosp, Dept Obstet 3, Shijiazhuang 050011, Peoples R China
[5] Shijiazhuang Obstet & Gynecol Hosp, Dept Obstet 7, Shijiazhuang 050011, Peoples R China
[6] Peking Univ, Lab Toxicol Res & Risk Assessment Food Safety, 38 Xue Yuan Rd, Beijing 100191, Peoples R China