title: Breastfeeding duration and non-verbal IQ in children.
abstract: BACKGROUND
  Breastfeeding has been related to better cognitive development in children. However, due to methodological challenges, such as confounding, recall bias or insufficient power, the mechanism and nature of the relation remains subject to debate.
  
  
  METHODS
  We included 3761 participants of a population-based cohort study from fetal life onwards and examined the association of breastfeeding duration with non-verbal intelligence in children of age 6 years. Maternal and paternal lifestyle, sociodemographic factors, child factors and maternal IQ were tested for their confounding effects on the association.
  
  
  RESULTS
  We observed an initial association between breastfeeding duration and child IQ conferring an advantage of 0.32 (0.20 to 0.44) points for each additional month of breastfeeding. This association strongly attenuated to 0.09 (-0.03 to 0.21) points after adjustment for child factors, sociodemographic factors, parental lifestyle factors and maternal IQ. Similarly, the associations with breastfeeding duration as a categorical variable largely disappeared after confounding factors were added to the models.
  
  
  CONCLUSIONS
  The association between breastfeeding and child IQ can be largely explained by sociodemographic factors, parental lifestyle and maternal IQ. Our results cannot confirm beneficial effects of breastfeeding on child intelligence.
authors.affiliation: The Generation R Study Group, Erasmus MC, Rotterdam, The Netherlands Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Ayesha
authors.initials: A
authors.lastname: Sajjad
authors.affiliation: Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands Department of Child and Adolescent Psychiatry & Psychology, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Anne
authors.initials: A
authors.lastname: Tharner
authors.affiliation: Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Jessica C
authors.identifier: http://orcid.org/0000-0002-8136-0918
authors.initials: JC
authors.lastname: Kiefte-de Jong
authors.affiliation: The Generation R Study Group, Erasmus MC, Rotterdam, The Netherlands Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands Department of Pediatrics, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Vincent V W
authors.initials: VV
authors.lastname: Jaddoe
authors.affiliation: The Generation R Study Group, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Albert
authors.initials: A
authors.lastname: Hofman
authors.affiliation: Department of Child and Adolescent Psychiatry & Psychology, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Frank C
authors.initials: FC
authors.lastname: Verhulst
authors.affiliation: Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Oscar H
authors.initials: OH
authors.lastname: Franco
authors.affiliation: Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands Department of Child and Adolescent Psychiatry & Psychology, Erasmus MC, Rotterdam, The Netherlands Department of Psychiatry, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Henning
authors.initials: H
authors.lastname: Tiemeier
authors.affiliation: Department of Child and Adolescent Psychiatry & Psychology, Erasmus MC, Rotterdam, The Netherlands Department of Psychiatry, Erasmus MC, Rotterdam, The Netherlands.
authors.forename: Sabine J
authors.initials: SJ
authors.lastname: Roza
mesh_terms: D001942:Breast Feeding / Q000706:statistics & numerical data*; D002648:Child; D002657:Child Development; D003071:Cognition; D015986:Confounding Factors, Epidemiologic; D005260:Female; D006801:Humans; D007360:Intelligence; D007361:Intelligence Tests; D016014:Linear Models; D008297:Male; D008895:Milk, Human / Q000737:chemistry* / Q000502:physiology; D009035:Mothers / Q000706:statistics & numerical data; D009426:Netherlands; D009633:Nonverbal Communication; D016487:Parenting; D012959:Socioeconomic Factors; D013997:Time Factors
keywords: BREAST FEEDING; CHILD HEALTH; COGNITION