New mothers need more studies into the merits of breastfeeding like fish need umbrellas.
Still, the developed world remains fascinated by the effects of mothers’ milk on the long-term development of children. A new study from Brazil, published in The Lancet, found that breastfed babies were more likely to have higher IQs, spend more time in school, and end up in higher-paying jobs.
A group of more than 5,000 mothers with babies born in 1982 in Pelotas, a medium-sized city in southern Brazil, were asked about their feeding regimes. The cohort was followed-up several times over the next 30 years, and 3,493 of those babies were available as adults for a concluding set of examinations.
The highest-achievers were those who were breastfed for between six and 11.9 months. They had a mean IQ of 101.3 points, compared with 96.4 for those who were breastfed for less than one month or not at all.
The six-to-11.9-month group also had a mean 12.1 years of schooling, compared with 10.9 years in the group that was fed by other methods. They also had a monthly income of 1,915 reais ($588), compared with 1,238 ($380) for the non-breastfed group.
The researchers took into account a number of factors, such as maternal health and family income. But there were also a number of limiting factors: it was rare that babies in Brazil were exclusively breastfed. Information was also obtained substantially after the fact, meaning that recall of events may not always have been accurate.
But the researchers were able to conclude with some confidence that alongside short-term benefits—like reducing child mortality and infectious diseases—breastfeeding also has long term financial benefits.
Bernardo Lessa Horta, one of the study’s coordinators, said (audio) that higher IQ was the main factor behind higher earnings, and that the higher IQ could be put down to early breastfeeding. He added that the study was the first to examine a population that was not already privileged, because in higher-income countries breastfeeding is more likely to be associated with greater wealth than in a lower-income country like Brazil.