[1] McMaster Univ, Fac Sci, Hamilton, ON, Canada
[2] McGill Univ, Dept Epidemiol Biostat & Occupat Hlth, Montreal, PQ, Canada
[3] McMaster Univ, Div Maternal Fetal Med, Dept Obstet & Gynecol, Hamilton, ON, Canada
[4] McMaster Univ, Div Maternal Fetal Med, Dept Radiol, Hamilton, ON, Canada
[5] McMaster Univ, Div Maternal Fetal Med, Dept Hlth Res Methods Evidence & Impact, Hamilton, ON, Canada