1. Department of Obstetrics and Gynecology, Faculty of Medicine; Chiang Mai University; Chiang Mai 50200 Thailand
2. Department of Pathology, Faculty of Medicine; Chiang Mai University; Chiang Mai 50200 Thailand
3. Department of Surgery, Faculty of Medicine; Chiang Mai University; Chiang Mai 50200 Thailand
4. Department of Pediatrics, Faculty of Medicine; Chiang Mai University; Chiang Mai 50200 Thailand