1. Doctoral Program of Biomedicine, Faculty of Medicine, Andalas University, Padang, Indonesia
2. Departement of Anesthesiology and Critical Care, Faculty of Medicine, Riau University, Riau, Indonesia
3. Departement of Obstetrics and Gynecology, Faculty of Medicine, Andalas University, Padang, Indonesia
4. Departement of Obstetrics and Gynecology, Faculty of Medicine, Sumatera Utara University, Medan, Indonesia
5. Departement of Anaesthesiology and Critical Care, Faculty of Medicine, Padjadjaran University, Bandung, Indonesia