[1] McGill Univ, Hlth Ctr, Dept Obstet & Gynecol, Montreal, PQ, Canada
[2] Sidney Liswood Hlth Sci Lib, Dept Mt Sinai Hosp, Toronto, ON, Canada
[3] Univ Toronto, Biostat Res Unit, Univ Hlth Network, Mt Sinai Hosp, Toronto, ON, Canada
[4] Queens Univ, Kingston Gen Hosp, Dept Obstet & Gynecol, Kingston, ON, Canada