1. Faculty of Medicine Vajira Hospital, Navamindradhiraj University; Department of Obstetrics and Gynecology; Samsen Road Dusit Bangkok Thailand 10300
2. Chulalongkorn University; Department of Obstetrics and Gynecology, Faculty of Medicine; Rama IV Road, Pathumwan Bangkok Thailand 10330
3. Oregon Health and Science University; Department of Obstetrics and Gynecology; 3181 S.W. Sam Jackson Park Road Portland Oregon USA 97239
4. Khon Kaen University; Department of Obstetrics and Gynaecology, Faculty of Medicine; 123 Mitraparb Road Amphur Muang Khon Kaen Thailand 40002