[Peng, Chang; Yang, Mengsi; Liu, Xiaoqun] Cent South Univ, Xiangya Sch Publ Hlth, Dept Maternal & Child Hlth, Changsha, Peoples R China.
[Peng, Chang; Yu, Yizhen] Huazhong Univ Sci & Technol, Tongji Med Coll, Sch Publ Hlth, Dept Maternal Child & Adolescent Hlth, Wuhan, Peoples R China.
[Qing, Zaihua] Hunan Univ Finance & Econ, Dept Student Affairs, Changsha, Peoples R China.
[Qiu, Xiaoyan] Hunan Univ Sci & Engn, Inst Higher Educ, Yongzhou, Peoples R China.
[Yang, Xinhua] Hunan Agr Univ, Inst Educ, Changsha, Peoples R China.