[1] Cent South Univ, Xiangya Sch Publ Hlth, Changsha 410008, Hunan, Peoples R China
[2] Peking Univ, Inst Child & Adolescent Hlth, Sch Publ Hlth, Natl Hlth Commiss,Key Lab Reprod Hlth, Beijing 100191, Peoples R China
[3] Sun Yat Sen Univ, Sch Publ Hlth, Dept Maternal & Child Hlth, Guangzhou 510080, Guangdong, Peoples R China
[4] Tianjin Med Univ, Sch Publ Hlth, Tianjin 300070, Peoples R China
[5] Shanghai Municipal Ctr Dis Control & Prevent, Dept Sch Hlth, Shanghai 200336, Peoples R China
[6] Shanghai Inst Prevent Med, Shanghai 200336, Peoples R China
[7] Chongqing Med Univ, Sch Publ Hlth & Management, Chongqing 400016, Peoples R China
[8] Ningxia Med Univ, Sch Publ Hlth & Management, Yinchuan 750004, Ningxia, Peoples R China
[9] Liaoning Hlth Supervis Bur, Shenyang 110000, Liaoning, Peoples R China