1. School of Nursing Peking University Beijing China
2. School of Nursing Capital Medical University Beijing China
3. School of Florence Nightingale Faculty of Nursing, Midwifery and Palliative Care King's College London London UK
4. Department of Obstetrics and Gynecology First Affiliated Hospital of Kunming Medical University Kunming China
5. Department of Obstetrics and Gynecology Peking University Third Hospital Beijing China
6. National Clinical Research Center for Obstetrics and Gynecology (Peking University Third Hospital) Beijing China