1. Division of Maternal-Fetal Medicine, Department of Obstetrics & Gynecology, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
2. Department of Social Sciences, Faculty of Social Sciences and Humanities, Mahidol University, Nakhon Pathom 73170, Thailand
3. Clinical Epidemiological Unit, Office for Research and Development, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand