1. Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Canada
2. School of Medicine, University of Galway, Galway, Ireland
3. Department of Obstetrics, Gynecology and Newborn Care, The Ottawa Hospital, Ottawa, Canada
4. Department of Obstetrics and Gynecology, University of Toronto, Toronto, Canada
5. Faculty of Science, University of Ottawa, Ottawa, Canada
6. Faculty of Medicine, University of Ottawa, Ottawa, Canada
7. Department of Obstetrics and Gynecology, University of Ottawa, Ottawa, Canada
8. School of Epidemiology and Public Health, University of Ottawa, Ottawa, Canada