1. Department of Anaesthesia and Pain Medicine, King Edward Memorial Hospital for Women, Subiaco, Western Australia
2. University of Western Australia, Perth, Western Australia
3. Department of Anaesthesia and Pain Medicine, King Edward Memorial Hospital for Women, Subiaco, Western Australia and Clinical Associate Professor, School of Medicine and Pharmacology and School of Women's and Infants’ Health, University of Western Australia, Perth, Western Australia
4. Biostatistics and Research Design Unit, Women and Infants Research Foundation, Perth, Western Australia
5. School of Medicine and Pharmacology, University of Western Australia, Perth, Western Australia, Department of Anaesthesia and Pain Medicine, King Edward Memorial Hospital for Women, Subiaco, Western Australia