[1] Univ Manchester, ARC Epidemiol Unit, Manchester, Lancs, England
[2] Univ Southampton, MRC Environm Epidemiol Unit, Southampton, Hants, England
[3] Univ Manchester, Sch Nursing Midwifery & Hlth Visiting, Manchester, Lancs, England
[4] VU Acad Ziekenkuis, Dept Endocrinol, Amsterdam, Netherlands
[5] Inst Publ Hlth, Cambridge, England