1. Department of Obstetrics and Gynecology, Faculty of Medicine, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand
2. Department of Obstetrics and Gynaecology, Srinakharinwirot University, Ongkharak, Nakhon Nayok, Thailand
3. Department of Obstetrics and Gynecology, Faculty of Medicine, King Chulalongkorn Memorial Hospital, Bangkok, Thailand