1. Medical Research Council (MRC) Epidemiology Unit (K.K.O.), Cambridge CB2 0QQ, United Kingdom
2. Department of Paediatrics (K.K.O., D.B.D.), University of Cambridge, Cambridge CB2 0QQ, United Kingdom
3. Department of Community Based Medicine (P.E., J.G., I.R.), University of Bristol, Bristol BS8 2BN, United Kingdom
4. Department of Social Medicine (K.N., A.R.N.), University of Bristol, Bristol BS8 2BN, United Kingdom
5. Department of Oral and Dental Science (A.R.N.), University of Bristol, Bristol BS1 2LY, United Kingdom
6. MRC Childhood Nutrition Research Centre (J.C.W.), Institute of Child Health, London WC1N 1EH, United Kingdom