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Breastfeeding duration and non-verbal IQ in children
  1. Ayesha Sajjad1,2,
  2. Anne Tharner2,3,
  3. Jessica C Kiefte-de Jong2,
  4. Vincent VW Jaddoe1,2,4,
  5. Albert Hofman1,
  6. Frank C Verhulst3,
  7. Oscar H Franco2,
  8. Henning Tiemeier2,3,5,
  9. Sabine J Roza3,5
  1. 1The Generation R Study Group, Erasmus MC, Rotterdam, The Netherlands
  2. 2Department of Epidemiology, Erasmus MC, Rotterdam, The Netherlands
  3. 3Department of Child and Adolescent Psychiatry & Psychology, Erasmus MC, Rotterdam, The Netherlands
  4. 4Department of Pediatrics, Erasmus MC, Rotterdam, The Netherlands
  5. 5Department of Psychiatry, Erasmus MC, Rotterdam, The Netherlands
  1. Correspondence to Sabine J Roza, Department of Psychiatry, Room Dp-0430, Erasmus MC, University Medical Center Rotterdam, P.O. Box 2040, Rotterdam 3000 CA, The Netherlands; s.roza{at}


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.


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