Longer Breastfeeding Duration Linked To Higher Earning Ability, IQ

New findings published in The Lancet Global Health journal show that a longer duration of breastfeeding was linked to a higher adult IQ and earning ability, in some instances.

"The effect of breastfeeding on brain development and child intelligence is well established, but whether these effects persist into adulthood is less clear," said lead study author Dr Bernardo Lessa Horta from the Federal University of Pelotas in Brazil, in a news release.

"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. 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."

For the study, researchers analyzed data from a prospective study of close to 6,000 infants born in Pelotas, Brazil in 1982. Participants were given an IQ test at the average age of 30 and collected information on breastfeeding during the early childhood years. Information on educational achievement and income was also collected.

Breastfeeding and IQ information were available on just about half of the participants while researchers simultaneously divided the subjects into five groups that were based on the length of time the infants were breastfed. Ten social and biological variables that also contributed to the IQ were shown to increase, including parental school, maternal smoking during pregnancy, maternal age, birth weight, delivery type, and genomic ancestry.

The study showed an increase in adult intelligence and higher earnings overall. Yet the benefits were greater based on longer durations of breastfeeding (up to 12 months.)