1. Department of Obstetrics and Gynaecology Prince of Wales Hospital, The Chinese University of Hong Kong Hong Kong China
2. Obstetrics & Gynecology, Department of Obstetrics & Gynecology Kingston Health Sciences Centre, Queen's University Kingston Ontario Canada
3. Department of Obstetrics and Gynecology, Institute of clinical sciences Sahlgrenska Academy, University of Gothenburg Gothenburg Sweden
4. Department of Obstetrics and Gynecology Stellenbosch University Cape Town South Africa
5. Department of Women's and Children's Health Uppsala University Uppsala Sweden
6. UCD Perinatal Research Centre, School of Medicine University College Dublin, National Maternity Hospital Dublin Ireland