1 Department of Obstetrics and Department of Gynecology, Division of Maternal-Fetal Medicine Radiology and Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, ON L8S 4K1, Canada. Electronic address: mcdonals@mcmaster.ca.
2 Department of Obstetrics and Gynaecology, Division of Maternal Fetal Medicine, Mount Sinai Hospital and University of Toronto, Toronto, ON, Canada.