1. Department of Obstetrics and Gynaecology, Faculty of Medicine, Ramathidodi Hospital, Mahidol University, Bangkok, Thailand.
2. Section for Clinical Epidemiology and Biostatistics, and Faculty of Medicine, Ramathidodi Hospital, Mahidol University, Bangkok, Thailand.
3. Reproductive Endocrinology and Infertility Unit, Faculty of Medicine, Ramathidodi Hospital, Mahidol University, Bangkok, Thailand.