1 Department of Obstetrics and Gynaecology (Brent, Christakis, Shirreff), University of Toronto; Department of Obstetrics and Gynecology (Christakis), St. Michael's Hospital; Department of Obstetrics and Gynaecology (Shirreff), Mount Sinai Hospital, Toronto, Ont. shannon.brent@mail.utoronto.ca.
2 Department of Obstetrics and Gynaecology (Brent, Christakis, Shirreff), University of Toronto; Department of Obstetrics and Gynecology (Christakis), St. Michael's Hospital; Department of Obstetrics and Gynaecology (Shirreff), Mount Sinai Hospital, Toronto, Ont.