title: Developmental trajectories of body mass index in early childhood and their risk factors: an 8-year longitudinal study.
abstract: OBJECTIVE
  To identify groups of children with distinct developmental trajectories of body mass index (BMI), calculated as weight in kilograms divided by height in meters squared, between the ages of 5 months and 8 years and identify early-life risk factors that distinguish children in an atypically elevated BMI trajectory group.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Families with a child born between October 1997 and July 1998 in the province of Quebec, Canada.
  
  
  METHODS
  A representative sample of children (N = 2120) selected through birth registries for the Quebec Longitudinal Study of Child Development. Children for whom BMI data were available for at least 5 time points were retained in the present study (n = 1957).
  
  
  METHODS
  Early-life factors putatively associated with BMI, assessed by maternal report.
  
  
  METHODS
  Group-based trajectories of children's BMI, identified with a semiparametric modeling method from raw BMI values at each age.
  
  
  RESULTS
  Three trajectories of BMI were identified: low-stable (54.5% of children), moderate (41.0%), and high-rising (4.5%). The high-rising group was characterized by an increasing average BMI, which exceeded international cutoff values for obesity by age 8 years. Two maternal risk factors were associated with the high-rising group as compared with the low-stable and moderate groups combined: maternal BMI (odds ratio, 2.38; 95% confidence interval, 1.38-4.54 for maternal overweight and 6.33; 3.82-11.85 for maternal obesity) and maternal smoking during pregnancy (2.28; 1.49-4.04).
  
  
  CONCLUSIONS
  Children continuing on an elevated BMI trajectory leading to obesity in middle childhood can be distinguished from children on a normative BMI trajectory as early as age 3.5 years. Important and preventable risk factors for childhood obesity are in place before birth.
authors.affiliation: Groupe de Recherchesur l’inadaptation psychosociale chez l’enfant [GRIP], Université de Montréal, 3050 Edouard-Montpetit, Montréal, Quebec, Canada.
authors.forename: Laura E
authors.initials: LE
authors.lastname: Pryor
authors.forename: Richard E
authors.initials: RE
authors.lastname: Tremblay
authors.forename: Michel
authors.initials: M
authors.lastname: Boivin
authors.forename: Evelyne
authors.initials: E
authors.lastname: Touchette
authors.forename: Lise
authors.initials: L
authors.lastname: Dubois
authors.forename: Christophe
authors.initials: C
authors.lastname: Genolini
authors.forename: Xuecheng
authors.initials: X
authors.lastname: Liu
authors.forename: Bruno
authors.initials: B
authors.lastname: Falissard
authors.forename: Sylvana M
authors.initials: SM
authors.lastname: Côté
mesh_terms: D015992:Body Mass Index; D002648:Child; D002657:Child Development / Q000502:physiology*; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008137:Longitudinal Studies; D008297:Male; D008425:Maternal Behavior; D008429:Maternal Welfare; D050177:Overweight / Q000453:epidemiology* / Q000503:physiopathology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000453:epidemiology*; D011446:Prospective Studies; D011792:Quebec / Q000453:epidemiology; D012307:Risk Factors; D012907:Smoking / Q000453:epidemiology; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires