[1] UCL, GOS Inst Child Hlth, 30 Guildford St, London WC1 1EH, England
[2] Karolinska Inst, Inst Environm Med, S-17177 Stockholm, Sweden
[3] Univ Liverpool, Dept Publ Hlth & Policy, Liverpool L69 3BX, Merseyside, England
[4] Childrens Hosp Wales, Dept Child Hlth, Cardiff CF14 4XW, S Glam, Wales
[5] Queen Mary Univ London, William Harvey Res Inst, Ctr Endocrinol, London EV1M 6BQ, England
[6] Barts Hlth NHS Trust Royal London Childrens Hosp, Dept Paediat Endocrinol, London E1 1BB, England