title: Maternal pre-pregnancy BMI and intelligence quotient (IQ) in 5-year-old children: a cohort based study.
abstract: BACKGROUND
  An association between maternal pre-pregnancy BMI and childhood intelligence quotient (IQ) has repeatedly been found but it is unknown if this association is causal or due to confounding caused by genetic or social factors.
  
  
  METHODS
  We used a cohort of 1,783 mothers and their 5-year-old children sampled from the Danish National Birth Cohort. The children participated between 2003 and 2008 in a neuropsychological assessment of cognitive ability including IQ tests taken by both the mother and the child. Linear regression analyses were used to estimate the associations between parental BMI and child IQ adjusted for a comprehensive set of potential confounders. Child IQ was assessed with the Wechsler Primary and Preschool Scales of Intelligence--Revised (WPPSI-R).
  
  
  RESULTS
  The crude association between maternal BMI and child IQ showed that BMI was adversely associated with child IQ with a reduction in IQ of -0.40 point for each one unit increase in BMI. This association was attenuated after adjustment for social factors and maternal IQ to a value of -0.27 (-0.50 to -0.03). After mutual adjustment for the father's BMI and all other factors except maternal IQ, the association between paternal BMI and child IQ yielded a regression coefficient of -0.26 (-0.59 to 0.07), which was comparable to that seen for maternal BMI (-0.20 (-0.44 to 0.04)).
  
  
  CONCLUSIONS
  Although maternal pre-pregnancy BMI was inversely associated with the IQ of her child, the similar association with paternal BMI suggests that it is not a specific pregnancy related adiposity effect.
authors.affiliation: Department of Gynaecology and Obstetrics, Odense University Hospital, and Institute of Clinical Research, Research Unit of Gynaecology and Obstetrics, University of Southern Denmark, Odense, Denmark.
authors.forename: Mette
authors.initials: M
authors.lastname: Bliddal
authors.affiliation: Department of Public Health, Section for Epidemiology, Aarhus University, Aarhus, Denmark.
authors.forename: Jørn
authors.initials: J
authors.lastname: Olsen
authors.affiliation: Department of Public Health, Section for Biostatistics, Aarhus University, Aarhus, Denmark.
authors.forename: Henrik
authors.initials: H
authors.lastname: Støvring
authors.affiliation: Center of Functionally Integrative Neuroscience, Institute for Clinical Medicine, Aarhus University, Aarhus, Denmark.
authors.forename: Hanne-Lise F
authors.initials: HL
authors.lastname: Eriksen
authors.affiliation: Department of Obstetrics and Gynaecology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Ulrik S
authors.initials: US
authors.lastname: Kesmodel
authors.affiliation: Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Denmark; Institute of Preventive Medicine, Bispebjerg and Frederiksberg Hospitals - Part of Copenhagen University Hospital, Copenhagen, Denmark.
authors.forename: Thorkild I A
authors.initials: TI
authors.lastname: Sørensen
authors.affiliation: Department of Public Health, Section for Epidemiology, Aarhus University, Aarhus, Denmark.
authors.forename: Ellen A
authors.initials: EA
authors.lastname: Nøhr
mesh_terms: D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007361:Intelligence Tests; D008019:Life Style; D008297:Male; D011247:Pregnancy
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