[1] Canc Care Ontario, Toronto, ON M5G 2L7, Canada
[2] Univ Toronto, Fac Med, Dalla Lana Sch Publ Hlth, Div Epidemiol, Toronto, ON, Canada
[3] Mt Sinai Hosp, Samuel Lunenfeld Res Inst, Toronto, ON M5G 1X5, Canada
[4] Mt Sinai Hosp, Maternal Infant Care Res Ctr, Toronto, ON M5G 1X5, Canada
[5] Univ Toronto, Fac Med, Dalla Lana Sch Publ Hlth, Div Biostat, Toronto, ON, Canada
[6] York Univ, Sch Kinesiol & Hlth Sci, Fac Hlth, Toronto, ON M3J 2R7, Canada