title: Socioeconomic status and trajectory of overweight from birth to mid-childhood: the Early Childhood Longitudinal Study-Birth Cohort.
abstract: OBJECTIVE
  Our objective was to use longitudinal data from a US birth cohort to test whether the probability of overweight or obesity during the first 6 years of life varied according to socioeconomic status.
  
  
  METHODS
  Using six waves of longitudinal data from full-term children in the Early Childhood Longitudinal Study-Birth Cohort (2001-2007; n≈4,950), we examined the prevalence of overweight or obesity (Body Mass Index (BMI)>2 standard deviations above age- and sex- specific WHO Childhood Growth Standard reference mean; henceforth, "overweight/obesity") according to age, socioeconomic status, and race/ethnicity using generalized estimating equation models.
  
  
  RESULTS
  The association between socioeconomic status and overweight/obesity varied significantly by race/ethnicity, but not by sex. Overweight/obesity was significantly associated with socioeconomic status among whites, Hispanics and Asians; the adjusted odds of overweight/obesity began to diverge according to SES after the first 9 months of life. By approximately 4 years, children with the highest SES had a significantly lower odds of overweight/obesity. SES was not significantly related to overweight/obesity among African Americans and American Indians during early childhood.
  
  
  CONCLUSIONS
  Few studies have assessed the associations between SES and overweight/obesity within racial/ethnic groups in the US. We find that in contemporary, US-born children, SES was inversely associated with overweight/obesity among more racial/ethnic groups (whites, Hispanics, and Asians) than previously reported.
authors.affiliation: Department of International Health (Human Nutrition), Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America; School of Public Health, University of California Berkeley, Berkeley, California, United States of America.
authors.forename: Jessica C
authors.initials: JC
authors.lastname: Jones-Smith
authors.affiliation: School of Public Health, University of California Berkeley, Berkeley, California, United States of America; School of Medicine, University of Louisville, Louisville, Kentucky, United States of America.
authors.forename: Marlowe Gates
authors.initials: MG
authors.lastname: Dieckmann
authors.affiliation: Department of Family and Community Medicine and Center for Health and Community, University of California San Francisco, San Francisco, California, United States of America.
authors.forename: Laura
authors.initials: L
authors.lastname: Gottlieb
authors.affiliation: University of California Berkeley University of California San Francisco Joint Medical Program (JMP), Berkeley, California, United States of America.
authors.forename: Jessica
authors.initials: J
authors.lastname: Chow
authors.affiliation: School of Public Health, University of California Berkeley, Berkeley, California, United States of America.
authors.forename: Lia C H
authors.initials: LC
authors.lastname: Fernald
mesh_terms: D002675:Child, Preschool; D015331:Cohort Studies; D005006:Ethnicity / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D009765:Obesity / Q000453:epidemiology / Q000208:ethnology; D016017:Odds Ratio; D050177:Overweight / Q000453:epidemiology* / Q000208:ethnology*; D044469:Racial Groups / Q000706:statistics & numerical data; D017678:Sex Distribution; D012923:Social Class; D014481:United States / Q000453:epidemiology / Q000208:ethnology