[1] Univ Oxford, Natl Perinatal Epidemiol Unit, Nuffield Dept Populat Hlth, Oxford, England
[2] Univ Oxford, Mill Women Study, Nuffield Dept Populat Hlth, Canc Epidemiol Unit, Oxford, England
[3] Birmingham City Univ, Nursing & Family Hlth, Birmingham, W Midlands, England