1. Department of Obstetrics and Gynecology, McMaster University, Hamilton, Ontario, Canada
2. Department of Obstetrics and Gynecology, University of British Columbia, Vancouver, British Columbia, Canada
3. Michael G. DeGroote School of Medicine, McMaster University, Hamilton, Ontario, Canada
4. Faculty of Health Sciences, McMaster University, Hamilton, Ontario, Canada
5. ICES, Toronto, Ontario, Canada
6. Department of Family Medicine, McMaster University, Hamilton, Ontario, Canada