[1] Univ Oxford, Nuffield Dept Populat Hlth, Natl Perinatal Epidemiol Unit, Oxford, England
[2] Univ Oxford, Populat Hlth Res Unit, Nuffield Dept Populat Hlth, MRC, Oxford, England
[3] Univ Oxford, Nuffield Dept Med, Oxford, England
[4] Kings Coll London, Fac Life Sci & Med, Sch Life Course Sci, Dept Women & Childrens Hlth, London, England