1. Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynaecology, Lunenfeld-Tanenbaum Research Institute, Sinai Health System, Toronto, Canada
2. Department of Obstetrics and Gynaecology, University of Toronto, Toronto, Canada
3. Department of Obstetrics and Gynaecology and Katharine Dormandy Haemophilia and Thrombosis Centre, The Royal Free NHS Foundation Hospital, London, United Kingdom
4. Institute for Women's Health, University College London, London, United Kingdom