1. Kalasin Hospital; Department of Obstetrics and Gynaecology; 202/1 Thedban 23rd Road Amphur Muang Kalasin Province Thailand 46000
2. Khon Kaen University; Department of Obstetrics and Gynaecology, Faculty of Medicine; 123 Mitraparb Road Amphur Muang Khon Kaen Thailand 40002
3. Khon Kaen University; Department of Biostatistics and Demography, Faculty of Public Health; Khon Kaen Thailand 40002