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Early life risk factors for obesity in childhood: cohort study

BMJ 2005; 330 doi: (Published 09 June 2005) Cite this as: BMJ 2005;330:1357
  1. John J Reilly (jjr2y{at}, reader in paediatric energy metabolism1,
  2. Julie Armstrong, senior lecturer in nutrition1,
  3. Ahmad R Dorosty, assistant professor3,
  4. Pauline M Emmett, senior research fellow in nutrition2,
  5. A Ness, senior lecturer in epidemiology2,
  6. I Rogers, research fellow in nutrition2,
  7. Colin Steer, research fellow in statistics2,
  8. Andrea Sherriff, research fellow in medical statistics, for the Avon Longitudinal Study of Parents and Children Study Team2
  1. 1University of Glasgow Division of Developmental Medicine, Yorkhill Hospitals, Glasgow G3 8SJ
  2. 2 Unit of Paediatric and Perinatal Epidemiology, Institute of Child Health, University of Bristol
  3. 3School of Public Health, Tehran University of Medical Sciences, Islamic Republic of Iran
  1. Correspondence to: J J Reilly
  • Accepted 19 April 2005


Objective To identify risk factors in early life (up to 3 years of age) for obesity in children in the United Kingdom.

Design Prospective cohort study.

Setting Avon longitudinal study of parents and children, United Kingdom.

Participants 8234 children in cohort aged 7 years and a subsample of 909 children (children in focus) with data on additional early growth related risk factors for obesity.

Main outcome measures Obesity at age 7 years, defined as a body mass index 3 95th centile relative to reference data for the UK population in 1990.

Results Eight of 25 putative risk factors were associated with a risk of obesity in the final models: parental obesity (both parents: adjusted odds ratio, 10.44, 95% confidence interval 5.11 to 21.32), very early (by 43 months) body mass index or adiposity rebound (15.00, 5.32 to 42.30), more than eight hours spent watching television per week at age 3 years (1.55, 1.13 to 2.12), catch-up growth (2.60, 1.09 to 6.16), standard deviation score for weight at age 8 months (3.13, 1.43 to 6.85) and 18 months (2.65, 1.25 to 5.59); weight gain in first year (1.06, 1.02 to 1.10 per 100 g increase); birth weight, per 100 g (1.05, 1.03 to 1.07); and short (< 10.5 hours) sleep duration at age 3 years (1.45, 1.10 to 1.89).

Conclusion Eight factors in early life are associated with an increased risk of obesity in childhood.


  • Contributors JJR, AS, JA, and PME obtained funding. JJR, ARD, AS, JA, and AN were responsible for the concept and design of the study. PME, IR, and CS collected the data. JJR, AS, and JA drafted the manuscript. AS, CS, and AN provided statistical expertise. All the authors were responsible for the analysis and interpretation of data and for critical revision of the manuscript. The funding bodies had no role in the decision to publish or the content of this article.

  • Funding This secondary analysis was funded by the Scottish Executive Health Department. The Avon longitudinal study of parents and children is funded by the Medical Research Council, Wellcome Trust, and various UK government departments, the US National Institutes of Health, a variety of medical research charities and commercial companies. ARD was funded by the Iranian Ministry of Health and Medical Education.

  • Conflict of interest None declared.

  • Ethical approval Law and ethics committee of the Avon longitudinal study of parents and children and the local research ethics committees.

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