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Breastfeeding for longer linked to higher IQ claim

Baby breastfed for at least a year gained four IQ points, claims study

Adrian O'Dowd

Thursday, 19 March 2015

Babies who are breastfed for longer tend to have a higher IQ when they become adults and have better earning ability, according to a study* published today in The Lancet Global Health journal.

Researchers have now agreed that current recommendations that babies be breastfed exclusively for six months should be upheld.

Breastfeeding has short-term benefits for child survival through reduction of morbidity and mortality from infectious diseases, but previous studies have also shown that it has long-term benefits such as a positive effect on brain development and child intelligence. However, it is less clear as to whether these effects persist into adulthood.

Researchers, therefore, from Brazil set out to assess the associations between infant feeding and IQ, educational attainment, and income in participants aged 30 years from a large population-based birth cohort.

A team of researchers led by Dr Bernardo Lessa Horta from the Federal University of Pelotas in Brazil, analysed data from a prospective study of 5,914 infants born in Pelotas, Brazil in 1982.

Information on breastfeeding was collected in early childhood and participants were given an IQ test at the average age of 30 years old with information on educational achievement and income also being collected.

Information on IQ and breastfeeding was available for just over half (3,493) of the participants.

The researchers divided these subjects into five groups based on the length of time they were breastfed as infants, while taking into account 10 social and biological variables that might contribute to the IQ increase including family income at birth, parental schooling, genomic ancestry, maternal smoking during pregnancy, maternal age, birthweight, and delivery type.

While the study showed increased adult intelligence, longer schooling, and higher adult earnings at all duration levels of breastfeeding, the longer a child was breastfed for (up to 12 months), the greater the scale of the benefits.

An infant, for example, who had been breastfed for at least a year gained a full four IQ points, had 0.9 years more schooling, and a higher income of 341 reais (Brazilian currency) per month, compared to those breastfed for less than one month.

Dr Horta said: “Our study provides the first evidence that prolonged breastfeeding not only increases intelligence until at least the age of 30 years but also has an impact both at an individual and societal level by improving educational attainment and earning ability.

“Previous studies from developed countries have been criticised for failing to disentangle the effect of breastfeeding from that of socioeconomic advantage, but our work addresses this issue for the first time.”

The researchers theorised that the likely mechanism underlying the beneficial effects of breast milk on intelligence was the presence of long-chain saturated fatty acids (DHAs) found in breast milk, which are essential for brain development.

Writing in a linked comment**, Dr Erik Mortensen from the University of Copenhagen in Denmark said: “This 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.”

Royal College of Midwives professional policy advisor Janet Fyle said: “This is interesting research adding to what we already know about the benefits of breastfeeding lasting well into adulthood.”


* Prof Cesar G Victora, et al. Association between breastfeeding and intelligence, educational attainment, and income at 30 years of age: a prospective birth cohort study from Brazil. The Lancet Volume 3, No. 4, e199–e205, April 2015.  DOI: 10.1016/S2214-109X(15)70002-1

** Erik Lykke Mortensen. Life course consequences of breastfeeding. Volume 3, No. 4, e179–e180, April 2015. DOI: 10.1016/S2214-109X(15)70078-1

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