1. First Department of Obstetrics, Shijiazhuang Obstetrics and Gynecology Hospital, Shijiazhuang, Hebei, China
2. Nursing Department, Shijiazhuang Fourth Hospital, Shijiazhuang, Hebei, China
3. Seventh Department of Obstetrics, Shijiazhuang Fourth Hospital, Shijiazhuang, Hebei, China
4. Third Department of Obstetrics, Shijiazhuang Fourth Hospital, Shijiazhuang, Hebei, China
5. Ward Management Center, Shijiazhuang Fourth Hospital, Shijiazhuang, Hebei, China