title: Perinatal and early childhood factors for overweight and obesity in young Canadian children.
abstract: BACKGROUND
  This study assessed potential early-life factors and their interrelationships with obesity among young Canadian children.
  
  
  METHODS
  Data from a nationally representative sample of children aged 6 to 11 years in the Canadian Health Measures Survey were analyzed. The associations of perinatal and early childhood behaviours and socio-economic factors with overweight or obesity were evaluated using multivariate logistic regression models. Adjusted population attributable risk fractions (PARFs) were calculated using multivariate logistic regression models.
  
  
  RESULTS
  Of 968 term-born children, 21% were overweight and another 13% were obese. Maternal smoking during pregnancy (adjusted odds ratio, 2.26; 95% confidence interval, 1.23-4.15) was positively associated with obesity. This association was mediated by birth weight (suppression effect); once controlled, the strength of the association between smoking and child obesity increased by 12%. Birth weight per 100 g (1.05; 1.005-1.09) was significantly associated with obesity. Exclusive breastfeeding for 6 months (0.44; 0.31-0.61), adequate sleep hours (0.39; 0.16-0.94) and being physically active (0.50; 0.26-0.93) were found to be protective. Breastfeeding, whether exclusive or not, significantly reduced obesity risk among children whose mothers never smoked in pregnancy. PARFs indicated that 24.4%, 11.5%, 11.3% and 6.0% prevalent cases of child obesity might be prevented by exclusive breastfeeding, smoking cessation during pregnancy, adequate sleep during childhood, and avoiding high birth weight, respectively.
  
  
  CONCLUSIONS
  This study identified multiple perinatal and childhood factors associated with obesity in young Canadian children. Effective prevention strategies targeting four modifiable maternal and child risk factors may reduce childhood obesity by up to 54% in Canada.
authors.affiliation: Social Determinants and Science Integration Directorate, Public Health Agency of Canada, Ottawa, ON. yipu.shi@phac-aspc.gc.ca
authors.forename: Yipu
authors.initials: Y
authors.lastname: Shi
authors.forename: Margaret
authors.initials: M
authors.lastname: De Groh
authors.forename: Howard
authors.initials: H
authors.lastname: Morrison
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001724:Birth Weight; D001942:Breast Feeding / Q000706:statistics & numerical data; D002170:Canada / Q000453:epidemiology; D002648:Child; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008423:Maternal Age; D008875:Middle Aged; D009043:Motor Activity; D009765:Obesity / Q000453:epidemiology* / Q000517:prevention & control; D050177:Overweight / Q000453:epidemiology* / Q000517:prevention & control; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012307:Risk Factors; D012890:Sleep; D012907:Smoking / Q000009:adverse effects*; D012959:Socioeconomic Factors; D055815:Young Adult
keywords: Canadian Health Measures Survey; Childhood obesity; birth weight; breastfeeding; maternal smoking