1 Clinical Epidemiology Program, Ottawa Hospital Research Institute, 501 Smyth Rd., CPCR, Box 241, Ottawa, Ontario, Canada K1H 8L6; Department of Obstetrics and Gynecology, University of Ottawa, Ottawa, Ontario, Canada; School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada. Electronic address: swwen@ohri.ca.
2 Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
3 Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; Department of Obstetrics and Gynecology, University of Ottawa, Ottawa, Ontario, Canada; School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada; Department of Obstetrics, Gynecology & Newborn Care, The Ottawa Hospital, Ottawa, Canada; Better Outcomes Registry & Network Ontario, Children's Hospital of Eastern Ontario, Ottawa, Canada.
4 Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; Department of Obstetrics and Gynecology, University of Ottawa, Ottawa, Ontario, Canada; School of Epidemiology and Public Health, University of Ottawa, Ottawa, Ontario, Canada; Department of Obstetrics, Gynecology & Newborn Care, The Ottawa Hospital, Ottawa, Canada.