1. School of Medicine, Walailak University, Nakhon Si Thammarat 80160, Thailand
2. Department of Obstetrics and Gynaecology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok 10400, Thailand
3. Department of Tropical Pathology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
4. Walailak University Hospital, Walailak University, Nakhon Si Thammarat 80160, Thailand
5. The Center for Scientific and Technological Equipment, Walailak University, Nakhon Si Thammarat 80160, Thailand