1. Division of Obstetrics and Gynaecology, The University of Western Australia, Perth, Australia;
2. Obstetrics and Gynaecology, King Edward Memorial Hospital, Perth, Australia;
3. Fiona Stanley Hospital, Perth, Australia;
4. Faculty of Medicine, Dentistry and Health Sciences, The University of Western Australia, Perth, Australia;
5. School of Medicine and Public Health, Newcastle University, Australia