[1] Univ Bristol, MRC Integrat Epidemiol Unit, Bristol, Avon, England
[2] Univ Bristol, Sch Social & Community Med, Bristol, Avon, England
[3] Univ Western Australia, Sch Womens & Infants Hlth, Perth, WA 6009, Australia
[4] Univ Western Australia, Sch Med & Pharmacol, Royal Perth Hosp Unit, Perth, WA 6009, Australia
[5] Univ Toronto, Samuel Lunenfeld Res Inst, Toronto, ON M5S 1A1, Canada
[6] Univ Toronto, Ontario Inst Canc Res, Toronto, ON M5S 1A1, Canada