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Breastfeeding effects on intelligence quotient in 4- and 11-year-old children
S W Jacobson1, L M Chiodo, J L Jacobson
1Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI 48201, USA.
Insights
Breastfeeding may not directly boost child IQ. The apparent advantage is linked to genetics and home environment, not just nutrition. Further research is needed.
Area of Science:
- Child Development
- Pediatrics
- Neuroscience
Background:
- Previous studies indicated a correlation between breastfeeding and higher child IQ.
- This association was observed even after controlling for socioeconomic factors.
- However, potential confounding maternal factors like IQ and parenting skills were not fully explored.
Purpose of the Study:
- To investigate the relationship between breastfeeding and child IQ.
- To determine if the IQ advantage persists after accounting for maternal IQ and parenting skills.
- To explore the underlying factors contributing to the observed association.
Main Methods:
- IQ was assessed in children at 4 and 11 years using standardized tests.
- Maternal IQ was measured using the Peabody Picture Vocabulary Test-Revised.
- Parenting skills were evaluated using the Home Observation for Measurement of the Environment (HOME).
Main Results:
- Breastfed children showed higher IQ scores at both ages, even after adjusting for social class and education.
- This breastfeeding advantage became non-significant when maternal IQ and parenting skills were included in the analysis.
- Similar reductions in significance were observed for reading achievement scores.
Conclusions:
- The IQ advantage associated with breastfeeding appears to be mediated by genetic and socioenvironmental factors.
- These findings suggest that the benefits of breastfeeding on neurodevelopment may not be solely nutritional.
- The medical benefits of breastfeeding remain significant and should not be overlooked.
Objective:
A study of preterm children found an IQ advantage among those who were breastfed as infants after controlling for maternal social class and educational status. However, this advantage needs to be examined in light of other maternal characteristics, such as maternal IQ and parenting skills, which were not measured in that study and which have been found to be related to breastfeeding.
Methodology:
IQ was assessed in 323 children at 4 years of age on the McCarthy Scales of Children's Abilities and the Peabody Picture Vocabulary Test-Revised and in 280 children on the Wechsler Intelligence Test for Children-Revised at 11 years of age.
Results:
Children who were breastfed in infancy had significantly higher scores on IQ tests at both ages, even after adjusting for social class and education, confirming the earlier findings and extending them to a predominantly full-term sample. However, the effect of breastfeeding was no longer significant after adjusting for maternal IQ assessed on the Peabody Picture Vocabulary Test-Revised and for parenting skills assessed on the Home Observation for Measurement of the Environment. Significant relations between breastfeeding and Woodcock Reading Achievement scores at 11 years were also reduced to nonsignificant levels after the inclusion of maternal IQ and the Home Observation for Measurement of the Environment.
Conclusions:
These findings suggest that the observed advantage of breastfeeding on IQ is related to genetic and socioenvironmental factors rather than to the nutritional benefits of breastfeeding on neurodevelopment. They should not be interpreted as detracting from the medical benefits associated with breastfeeding.