title: Birth weight and childhood obesity: a 12-country study.
abstract: OBJECTIVE
  Few studies have investigated the association between the full range of birth weight and the risk of childhood obesity in high-, middle- and low-income countries. The aim of the present study is to assess the association between different levels of birth weight and the risk of obesity among children aged 9-11 years in 12 countries.
  
  
  METHODS
  A multinational, cross-sectional study of 5141 children aged 9-11 years was conducted in 12 countries. Height and weight were obtained using standardized methods. Time spent in moderate-to-vigorous physical activity (MVPA), sedentary and sleeping were objectively measured using 24-h, waist-worn accelerometer (Actigraph GT3X+) monitored for 7 days. Birth weight and other factors (regions, parental education, maternal history of gestational diabetes, children age, gender, breast feeding, gestational age, unhealthy diet scores and healthy diet scores) were collected by parental and children's questionnaires. Multilevel modeling was used to account for the nested nature of the data.
  
  
  RESULTS
  The overall prevalence of obesity (BMI z-score>+2 s.d.) was 15.4% for boys and 10.0% for girls. There was a positive association between birth weight and BMI z-scores. The multivariable-adjusted odds ratios (ORs) of childhood obesity were significantly higher among children whose birth weights were 3500-3999 g (OR 1.45; 95% confidence interval (CI): 1.10-1.92), and >4000 g (OR 2.08; 95% CI: 1.47-2.93), compared with the reference group (2500-2999 g). The positive association between birth weight and the odds of childhood obesity was seen in girls, whereas a U-shaped association appeared in boys.
  
  
  CONCLUSIONS
  High levels of birth weight, defined as birth weight ⩾3500 g, were associated with increased odds of obesity among 9-11-year-old children in 12 countries. However, sex differences in the association between birth weight and the risk of obesity need to be considered when planning interventions to reduce childhood obesity.
authors.affiliation: Tianjin Women's and Children's Health Center, Tianjin, China; Pennington Biomedical Research Center, Baton Rouge, LA, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Qiao
authors.affiliation: Tianjin Women's and Children's Health Center , Tianjin, China.
authors.forename: J
authors.initials: J
authors.lastname: Ma
authors.affiliation: Tianjin Women's and Children's Health Center , Tianjin, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Tianjin Women's and Children's Health Center , Tianjin, China.
authors.forename: W
authors.initials: W
authors.lastname: Li
authors.affiliation: Pennington Biomedical Research Center , Baton Rouge, LA, USA.
authors.forename: P T
authors.initials: PT
authors.lastname: Katzmarzyk
authors.affiliation: Children's Hospital of Eastern Ontario Research Institute , Ottawa, Ontario, Canada.
authors.forename: J-P
authors.initials: JP
authors.lastname: Chaput
authors.affiliation: Department of Food and Environmental Sciences, University of Helsinki , Helsinki, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Fogelholm
authors.affiliation: Pennington Biomedical Research Center , Baton Rouge, LA, USA.
authors.forename: W D
authors.initials: WD
authors.lastname: Johnson
authors.affiliation: St Johns Research Institute , Bangalore, India.
authors.forename: R
authors.initials: R
authors.lastname: Kuriyan
authors.affiliation: St Johns Research Institute , Bangalore, India.
authors.forename: A
authors.initials: A
authors.lastname: Kurpad
authors.affiliation: Department of Human Biology, Faculty of Health Sciences, Division of Exercise Science and Sports Medicine, University of Cape Town , Cape Town, South Africa.
authors.forename: E V
authors.initials: EV
authors.lastname: Lambert
authors.affiliation: Alliance for Research in Exercise Nutrition and Activity (ARENA), School of Health Sciences, University of South Australia , Adelaide, South Australia, Australia.
authors.forename: C
authors.initials: C
authors.lastname: Maher
authors.affiliation: CIFI2D, Faculdade de Desporto, University of Porto , Porto, Portugal.
authors.forename: J
authors.initials: J
authors.lastname: Maia
authors.affiliation: Centro de Estudos do Laboratório de Aptidão Física de São Caetano do Sul (CELAFISCS) , Sao Paulo, Brazil.
authors.forename: V
authors.initials: V
authors.lastname: Matsudo
authors.affiliation: Alliance for Research in Exercise Nutrition and Activity (ARENA), School of Health Sciences, University of South Australia , Adelaide, South Australia, Australia.
authors.forename: T
authors.initials: T
authors.lastname: Olds
authors.affiliation: Department of Recreation Management and Exercise Science, Kenyatta University , Nairobi, Kenya.
authors.forename: V
authors.initials: V
authors.lastname: Onywera
authors.affiliation: School of Medicine, Universidad de los Andes , Bogota, Colombia.
authors.forename: O L
authors.initials: OL
authors.lastname: Sarmiento
authors.affiliation: University of Bath , Bath, UK.
authors.forename: M
authors.initials: M
authors.lastname: Standage
authors.affiliation: Children's Hospital of Eastern Ontario Research Institute , Ottawa, Ontario, Canada.
authors.forename: M S
authors.initials: MS
authors.lastname: Tremblay
authors.affiliation: Pennington Biomedical Research Center, Baton Rouge, LA, USA; Department of Kinesiology, University of Massachusetts Amherst, Amherst, MA, USA.
authors.forename: C
authors.initials: C
authors.lastname: Tudor-Locke
authors.affiliation: Pennington Biomedical Research Center , Baton Rouge, LA, USA.
authors.forename: T S
authors.initials: TS
authors.lastname: Church
authors.affiliation: Tianjin Women's and Children's Health Center , Tianjin, China.
authors.forename: P
authors.initials: P
authors.lastname: Zhao
authors.affiliation: Pennington Biomedical Research Center , Baton Rouge, LA, USA.
authors.forename: G
authors.initials: G
authors.lastname: Hu