1. School of Nursing, Peking University, Beijing, China
2. Department of Maternal and Child Health, School of Public Health, Peking University, Beijing, China
3. Chinese Maternal and Child Health Association, Beijing, China
4. Department of Women’s Health, Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, China
5. School of Nursing, Hebei Medical University, Hebei Province, China