title: Effects of body size and change in body size from infancy through childhood on body mass index in adulthood.
abstract: BACKGROUND
  Weight and weight gain throughout infancy are related to later obesity, but whether the strength of the associations varies during the infancy period is uncertain.
  
  
  OBJECTIVE
  Our aims were to identify the period of infancy when change in body weight has the strongest association with adult body mass index (BMI) and also the extent to which these associations during infancy are mediated through childhood BMI.
  
  
  METHODS
  The Copenhagen Perinatal Cohort, in which participants were followed from birth through 42 years of age, provided information on weight at 12 months and BMI at 42 years for 1633 individuals. Information on weight at birth, 2 weeks, 1, 2, 3, 4 and 6 months was retrieved from health visitors' records and information on BMI at ages 7 and 13 years from school health records. The associations of infant weight and weight gain standard deviation scores (SDS) with adult BMI-SDS were analyzed using multiple linear regression and path analysis.
  
  
  RESULTS
  Higher-weight-SDS at all ages from birth to an age 12 months were associated with higher-BMI-SDS at 42 years (regression coefficients 0.08-0.12). Infant weight gain-SDS was associated with greater BMI-SDS at 42 years only between birth and 3 months (0.09, 95% confidence intervals (CI) 0.04, 0.15) driven by an association between 2 and 3 months (0.12, 95% CI: 0.04, 0.20). The latter was partly mediated through later BMI in the path analysis. Infant weight gain-SDS between 3 and 12 months was not associated with greater BMI-SDS at 42 years.
  
  
  CONCLUSIONS
  Faster weight gain during only the first 3 months of infancy was associated with increased adult BMI, although not in a consistent monthly pattern. Adult BMI is more sensitive to high weight gain during early infancy than late infancy, but not specifically to the first month of life.
authors.affiliation: Institute of Preventive Medicine, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark.
authors.forename: L G
authors.initials: LG
authors.lastname: Bjerregaard
authors.affiliation: Division of Nutritional Sciences, Cornell University, Ithaca, NY, USA.
authors.forename: K M
authors.initials: KM
authors.lastname: Rasmussen
authors.affiliation: Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Copenhagen, Denmark.
authors.forename: K F
authors.initials: KF
authors.lastname: Michaelsen
authors.affiliation: Institute of Public Health, University of Southern Denmark, Odense, Denmark.
authors.forename: A
authors.initials: A
authors.lastname: Skytthe
authors.affiliation: 1] Institute of Preventive Medicine, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark [2] Institute of Public Health and Center for Healthy Aging, University of Copenhagen, Copenhagen, Denmark.
authors.forename: E L
authors.initials: EL
authors.lastname: Mortensen
authors.affiliation: 1] Institute of Preventive Medicine, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark [2] Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: J L
authors.initials: JL
authors.lastname: Baker
authors.affiliation: 1] Institute of Preventive Medicine, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark [2] Novo Nordisk Foundation Center for Basic Metabolic Research, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: T I A
authors.initials: TI
authors.lastname: Sørensen
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D001823:Body Composition; D015992:Body Mass Index; D001942:Breast Feeding / Q000706:statistics & numerical data*; D002648:Child; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D007227:Infant Nutritional Physiological Phenomena; D008297:Male; D009765:Obesity / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D011237:Predictive Value of Tests; D012307:Risk Factors; D013997:Time Factors; D055105:Waist Circumference; D015430:Weight Gain