1. Department of Obstetrics and Gynaecology Khon Kaen Hospital Khon Kaen Thailand
2. Department of Obstetrics and Gynaecology Faculty of Medicine Khon Kaen University Khon Kaen Thailand
3. Department of Obstetrics and Gynaecology Kalasin Hospital Kalasin Thailand
4. Department of Obstetrics and Gynaecology Lamphun Hospital Lamphun Thailand
5. Clinical Epidemiology Unit Faculty of Medicine Khon Kaen University Khon Kaen Thailand
6. Cochrane Thailand Faculty of Medicine Khon Kaen University Khon Kaen Thailand