title: Timing of excess weight gain in the Avon Longitudinal Study of Parents and Children (ALSPAC).
abstract: OBJECTIVE
  To test the hypothesis that most excess weight gain occurs by school entry in a large sample of English children, and to determine when the greatest gain in excess weight occurred between birth and 15 years.
  
  
  METHODS
  Longitudinal data were collected annually from birth to 15 years in 625 children. Weight and BMI at each time point were expressed relative to UK 1990 growth reference as z scores. Excess weight gain was calculated as the group increase in weight and BMI z scores between specific time periods.
  
  
  RESULTS
  Weight z score did not increase from birth to 5 years (mean difference: 0.04 [95% confidence interval (CI): -0.03-0.12] P = .30) but increased from 5 to 9 years (mean difference: 0.19 [95% CI: 0.14-0.23] P < .001). BMI z score increased from 7 to 9 years (mean difference: 0.22 [95% CI: 0.18-0.26] P < .001), with no evidence of a large increase before 7 years and after 9 years.
  
  
  CONCLUSIONS
  Our results do not support the hypothesis that most excess weight gain occurs in early childhood in contemporary English children. Excess weight gain was substantial in mid-childhood, with more gradual increases in early childhood and adolescence, which indicates that interventions to prevent excess weight should focus on school-aged children and adolescents as well as the preschool years.
authors.affiliation: Department of Sports Studies, University of Stirling, Stirling, Scotland.
authors.forename: Adrienne R
authors.initials: AR
authors.lastname: Hughes
authors.forename: Andrea
authors.initials: A
authors.lastname: Sherriff
authors.forename: Debbie A
authors.initials: DA
authors.lastname: Lawlor
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Ness
authors.forename: John J
authors.initials: JJ
authors.lastname: Reilly
mesh_terms: D000293:Adolescent; D001724:Birth Weight / Q000502:physiology*; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D004739:England / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009765:Obesity / Q000453:epidemiology*; D015995:Prevalence; D012307:Risk Factors; D013997:Time Factors; D015430:Weight Gain