[1] Univ Toronto, Dept Obstet & Gynecol, 123 Edward St,12th Floor, Toronto, ON M5G 1E2, Canada
[2] Univ Toronto, Dept Obstet & Gynecol, Prenatal Diag & Med Genet Program, Toronto, ON, Canada
[3] Univ Toronto, St Michaels Hosp, Dept Obstet & Gynaecol, Maternal Fetal Med, Toronto, ON, Canada