1 Department of Obstetrics and Gynaecology (Christakis, Shirreff), University of Toronto; Department of Obstetrics & Gynaecology (Christakis), St. Michael's Hospital; Department of Obstetrics & Gynaecology (Shirreff), Mount Sinai Hospital, Toronto, Ont. marie.christakis@unityhealth.to.
2 Department of Obstetrics and Gynaecology (Christakis, Shirreff), University of Toronto; Department of Obstetrics & Gynaecology (Christakis), St. Michael's Hospital; Department of Obstetrics & Gynaecology (Shirreff), Mount Sinai Hospital, Toronto, Ont.