Published on in Vol 6 , No 11 (2018) :November
Preprints (earlier versions) of this paper are available at https://preprints.jmir.org/preprint/11508, first published .
1 XiangYa School of Public Health, Central South University, Changsha, CN
2 Hunan Provincial Maternal and Child Health Hospital, Changsha, CN
3 Sun Yat-sen Global Health Institute, School of Public Health and Institute of State Governance, Sun Yat-sen University, Guangzhou, CN