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Longer breastfeeding duration associated with higher intelligence

In women of all socioeconomic statuses, breastfeeding was linked with increased intelligence and higher earning potential and educational attainment among adults, according to a recently published study in Lancet Global Health.

“What is unique about this study is the fact that, in the population we studied, breastfeeding was not more common among highly educated, high-income women, but was evenly distributed by social class. Previous studies from developed countries have been criticized for failing to disentangle the effect of breastfeeding from that of socioeconomic advantage, but our work addresses this issue for the first time,” Bernardo Lesso Horta, PhD, of the Universidade Federal de Pelotas in Brazil, said in a press release.

Between June 2014 and February 2013, Horta and colleagues assessed 3,493 participants who had been born in 1982 at one of five maternity hospitals in Pelotas, Brazil. Participants (mean age = 30 years) were evaluated for IQ using the Wechsler Adult Intelligence Scale, educational attainment and income, in relation to their breastfeeding duration.

Overall, the duration of total breastfeeding or predominant breastfeeding were positively linked to IQ, education level and income.

When adjusting for confounders, which included family income at birth, genomic ancestry, maternal smoking during pregnancy, maternal age, birth weight, delivery time and parental education, results demonstrated that participants who were breastfed for 12 or more months had higher IQ scores (3.76 point difference, 95% CI, 2.20-5.33), more years of education (0.91 years difference, 0.42-1.4) and higher monthly incomes (341 Brazilian reals, 93.8-588.3) compared with those who were breastfed for less than 1 month.

Researchers noted that analysis suggested that IQ was responsible for 72% of the increase on income.

In an accompanying editorial, Erikk L. Mortenson, of the department of public health and center for healthy aging at the University of Copenhagen, Denmark, noted that while the study does show an association between breastfeeding and cognitive development, analysis based on just income and intelligence may be a too simplified one.

“Victora and colleagues’ study suggests that the effects of breastfeeding on cognitive development persist into adulthood, and this has important public health implications…However, these findings need to be corroborated by future studies designed to focus on long-term effects and important life outcomes associated with breastfeeding,” Mortensen wrote. – by Casey Hower

Disclosure: The researchers report no relevant financial disclosures.