title: Childcare before age 6 and body mass index at age 7 years in a cohort of Danish children.
abstract: Previous studies show inconsistent associations between childcare and obesity.
  
  
  
  Our prior work demonstrated that childcare in infancy was associated with higher weight in a cohort of Danish children. Here, we extend this work and examine childcare through 6 years and body mass index (BMI) at age 7 years.
  
  
  
  We examined 24 714 children in the Danish National Birth Cohort who were also in the Childcare Database. We conducted multivariable linear regressions examining children prior to age 6, overall and by type (daycare, crèche, age-integrated and kindergarten), and BMI z-score at 7 years, stratifying on maternal socio-occupational status.
  
  
  
  A total of 19 760 (80.0%) children attended childcare before age 6. Childcare prior to age 6 was associated with BMI z-score at 7 years (0.004 units per each additional 6 months of care; 95% CI: 0.001, 0.008; p = 0.01). Childcare in a kindergarten was the only type of care associated with BMI (0.009 units; 95% CI: 0.003, 0.02; p = 0.01). For children of higher socio-occupational status mothers, childcare was associated with a 0.008 unit increase in BMI (95% CI: 0.004, 0.01; p > 0.001).
  
  
  
  Childcare was weakly associated with later BMI. This relationship was more pronounced in children from higher socio-occupational status mothers and children in kindergarten care.
authors.affiliation: Department of Health, Behavior and Society, Johns Hopkins University, Baltimore, USA.
authors.forename: S E
authors.initials: SE
authors.lastname: Benjamin Neelon
authors.affiliation: Institute of Preventive Medicine, Bispebjerg Hospital, Copenhagen, Denmark.|Institute of Preventive Medicine, Frederiksberg Hospital, Copenhagen, Denmark.
authors.forename: C
authors.initials: C
authors.lastname: Schmidt Morgen
authors.affiliation: Section of Social Medicine, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Kamper-Jørgensen
authors.affiliation: Obesity Prevention Program, Department of Population Medicine, Harvard Medical School and Harvard Pilgrim Health Care Institute, Boston, USA.
authors.forename: E
authors.initials: E
authors.lastname: Oken
authors.affiliation: Environmental influences on Child Health Outcomes (ECHO) Program, National Institutes of Health, Rockville, USA.
authors.forename: M W
authors.initials: MW
authors.lastname: Gillman
authors.affiliation: Department of Biostatistics and Bioinformatics, Duke University Medical Center, Durham, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Gallis
authors.affiliation: Institute of Preventive Medicine, Bispebjerg Hospital, Copenhagen, Denmark.|Institute of Preventive Medicine, Frederiksberg Hospital, Copenhagen, Denmark.|Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark.|Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.|MRC Integrative Epidemiology Unit, Bristol University, Bristol, UK.
authors.forename: T I A
authors.initials: TIA
authors.lastname: Sørensen
mesh_terms: D015992:Body Mass Index; D002648:Child; D002654:Child Care / Q000706:statistics & numerical data*; D002675:Child, Preschool; D016208:Databases, Factual; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D050177:Overweight / Q000453:epidemiology / Q000209:etiology; D063766:Pediatric Obesity / Q000453:epidemiology / Q000209:etiology*
keywords: Childcare; Danish National Birth Cohort; Denmark; Obesity