[1] McMaster Univ, McMaster Midwifery Res Ctr, Dept Obstet & Gynecol, Hamilton, ON, Canada
[2] McMaster Univ, Dept Obstet & Gynecol, Div Maternal Fetal Med, Hamilton, ON, Canada
[3] McMaster Univ, Dept Radiol, Div Maternal Fetal Med, Hamilton, ON, Canada
[4] McMaster Univ, Dept Clin Epidemiol, Div Maternal Fetal Med, Hamilton, ON, Canada
[5] McMaster Univ, Dept Biostat, Div Maternal Fetal Med, Hamilton, ON, Canada
[6] Univ Toronto, St Michaels Hosp, Dept Obstet & Gynecol, Div Maternal Fetal Med, Toronto, ON, Canada
[7] Univ Toronto, Sunnybrook Hlth Sci Ctr, Dept Obstet & Gynecol, Div Maternal Fetal Med, Toronto, ON, Canada
[8] Rotunda Hosp, Dept Obstet & Gynaecol, Dublin, Ireland