title: Behavioural early-life exposures and body composition at age 15 years.
abstract: OBJECTIVE
  Previous studies have demonstrated associations between some early-life exposures and later obesity, but most have used body mass index in childhood or adulthood as the outcome. The objective of this study was to investigate whether early-life exposures were associated with directly measured fat and lean mass in adolescence.
  
  
  METHODS
  This study used data on 4750 mother-offspring pairs, collected as a part of the Avon Longitudinal Study of Parents and Children, Bristol, UK between 1991 and 1992; associations between behavioural exposures occurring from conception up to 5 years of age (maternal and paternal smoking during pregnancy, breastfeeding, age at introduction to solids, dietary patterns and physical inactivity during early childhood) and offspring body composition measured by dual-energy X-ray absorptiometry at ~15 years were assessed.
  
  
  RESULTS
  After full adjustment for potential confounders, maternal smoking during pregnancy, having a junk food diet and spending more time watching television in early childhood were all associated with higher fat mass at age 15, whereas maternal smoking, having a healthy diet and playing computer games more frequently in early childhood were all associated with a higher lean mass at age 15. Associations with paternal smoking were generally weaker for both fat and lean mass, but as there was no strong statistical evidence for maternal vs paternal differences, confounding by social factors rather than a direct effect of maternal smoking cannot be ruled out. Early feeding was not associated with fat or lean mass at age 15.
  
  
  CONCLUSIONS
  This study does not provide compelling evidence for associations between most early-life factors and body composition in adolescence. However, possible associations with dietary patterns and physical inactivity in early childhood require further investigation in other cohorts that have direct measurements of adolescent body composition.
authors: Biomedical Research Unit in Nutrition, Diet and Lifestyle, School of Oral and Dental Sciences, University of Bristol, Bristol, UK.
authors: S D
authors: SD
authors: Leary
authors: Medical Research Council Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors: D A
authors: DA
authors: Lawlor
authors: Medical Research Council Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors: G
authors: G
authors: Davey Smith
authors: Medical Research Council Centre for Causal Analyses in Translational Epidemiology, School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors: M J
authors: MJ
authors: Brion
authors: Biomedical Research Unit in Nutrition, Diet and Lifestyle, School of Oral and Dental Sciences, University of Bristol, Bristol, UK.
authors: A R
authors: AR
authors: Ness