1. Department of Anesthesiology, Baotou Obstetrics and Gynecology Hospital, Inner Mongolia (the Third Hospital of Inner Mongolia Baotou Iron and Steel Group), Gaotou 014010, China
2. Department of Neonatal Pediatrics, Baotou Obstetrics and Gynecology Hospital, Inner Mongolia (the Third Hospital of Inner Mongolia Baotou Iron and Steel Group), Gaotou 014010, China
3. School of Public Health Baotou Medical College, Gaotou 014010, China
4. Department of Gynecology and Obstetrics, Baotou Obstetrics and Gynecology Hospital, Inner Mongolia (the Third Hospital of Inner Mongolia Baotou Iron and Steel Group), Gaotou 014010, China
5. Chuka University, Chuka 60400, Kenya