title: Growth in early life and the development of obesity by age 9 years: are there critical periods and a role for an early life stressor?
abstract: OBJECTIVE
  Rapid growth, possibly occurring in critical periods in early life, may be important for the development of obesity. It is unknown whether this is influenced by postnatal exposures such as age-relevant sources of stress. Frequent house moves may be one such stressor. We aimed to examine if there is a period of growth in early life critical for the development of child obesity by age 9 years and assess the role of house moves in modifying any relationships between early life growth and obesity at age 9 years.
  
  
  METHODS
  Prospective Australian birth cohort study.
  
  
  METHODS
  In all, 392 children with serial body size measurements from birth to age 9 years.
  
  
  METHODS
  Standardized body mass index (z-BMI) was available for six time points (spanning birth to 3½ years), and the total number of house moves between birth and 3½ years. The outcomes considered were z-BMI and % body fat (%BF) at age 9 years. Linear regression models were used to estimate the effects of serial measurements of z-BMI and number of house moves on the outcomes.
  
  
  RESULTS
  Life-course plots showed that z-BMI at 3½ years was a statistically significant predictor of z-BMI at 9 years (β=0.80; standard error (s.e.), 0.04), whereas z-BMI at 9 months (β=-1.13; s.e., 0.40) and 3½ years (β=4.82; s.e., 0.42) were significant predictors of %BF at age 9 years. There were statistically significant interactions between the number of house moves and change in z-BMI between 9 and 12 months, such that ≥ 3 house moves in early life amplified the detrimental effects of earlier rapid growth on both body size and composition at age 9 years.
  
  
  CONCLUSIONS
  In the absence of evidence for a single critical period, efforts to prevent overweight and obesity are required throughout childhood. In addition, modifiable postnatal stressors may exacerbate effects of early growth on obesity in later childhood.
authors: Discipline of Public Health, School of Population Health, The University of Adelaide, Adelaide, South Australia, Australia. lynne.giles@adelaide.edu.au
authors: L C
authors: LC
authors: Giles
authors: M J
authors: MJ
authors: Whitrow
authors: A R
authors: AR
authors: Rumbold
authors: C E
authors: CE
authors: Davies
authors: B
authors: B
authors: de Stavola
authors: J B
authors: JB
authors: Pitcher
authors: M J
authors: MJ
authors: Davies
authors: V M
authors: VM
authors: Moore
mesh_terms: D000223:Adaptation, Psychological; D000328:Adult; D017668:Age of Onset; D001315:Australia / Q000453:epidemiology; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003423:Critical Period, Psychological; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008016:Life Change Events; D008297:Male; D009765:Obesity / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D011446:Prospective Studies; D012931:Social Environment; D012959:Socioeconomic Factors