Longer duration of breastfeeding is linked with increased intelligence in adulthood, longer schooling, and higher adult earnings, according to a high profile study published earlier this week.
The study, published in The Lancet Global Health journal, followed a group of almost 3,500 newborns in Brazil for 30 years.
Researchers analysed data from infants born in 1982, collected information on breastfeeding during early childhood and gave participants an IQ test at around age of 30.
“Our study provides the first evidence that prolonged breastfeeding… increases intelligence until at least the age of 30 years”
Bernardo Lessa Horta
The researchers controlled for 10 factors that might contribute to the IQ increase – family income at birth, parental schooling, genomic ancestry, maternal smoking during pregnancy, maternal age, birthweight, and delivery type.
They said their study showed increased adult intelligence, longer schooling, and higher adult earnings at all duration levels of breastfeeding.
But the longer a child was breastfed for – up to 12 months – the greater the magnitude of the benefits, according to the researchers.
For example, an infant 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 per month at the age of 30 years, compared to those breastfed for less than one month.
The study authors suggested the “likely mechanism” underlying the beneficial effects of breast milk was the presence of long-chain saturated fatty acids (DHAs), which are essential for brain development.
“Health services need to make greater efforts to encourage new mothers to breastfeed and for longer”
“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,” said lead author Dr Bernardo Lessa Horta, from the Federal University of Pelotas.
“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,” he said.
“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,” he added.
Janet Fyle, professional policy advisor at the Royal College of Midwives, said the “interesting research” added to what was already known about the benefits of breastfeeding.
“Health services need to make greater efforts to encourage new mothers to breastfeed and for longer, through better support, considerate maternity leave and strengthening policies and legislative framework that enables women to breastfeed when out and about,” she said.
“This also highlights the importance of good postnatal support and access to midwives to give women the help they need to establish and continue breastfeeding,” she added.