1. Faculty of Medicine, Chiang Mai University; Department of Obstetrics and Gynecology; 110 Intawaroros Road Chiang Mai Thailand 50200
2. The University of Manchester, Manchester Academic Health Science Centre; Division of Nursing, Midwifery and Social Work, School of Health Sciences, Faculty of Biology, Medicine and Health; Jean McFarlane Building Oxford Road Manchester UK M13 9PL
3. Chiang Mai University; Division of Vascular and Endovascular Surgery, Department of Surgery, Faculty of Medicine; Chiang Mai Thailand
4. Chiang Mai University; Faculty of Medicine; Chiang Mai Thailand