Family life

Study links breastfeeding and higher IQs in adulthood

New research finds a connection between breastfeeding and higher IQs in adulthood—but Jennifer Pinarski is skeptical.

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Photo: iStockphoto

Sometimes it feels like a new study on raising smart kids is released every day. But a new research out of the Federal University of Pelotas in Brazil suggests that breastfeeding trumps all else when it comes to rearing a whip-smart child—resulting in adults who have higher IQs, are in school longer and earn more money. Lead study author Dr. Bernardo Lessa Horta published his findings in the April issue of The Lancet Global Health Journal.

“The effect of breastfeeding on brain development and child intelligence is well established, but whether these effects persist into adulthood is less clear,” Dr. Horta says in an interview with Nicholai Humphreys on The Lancet Global Health podcast. “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.”

Information on the duration of breastfeeding was collected from the parents of 5,914 Brazilian-born babies born in 1982. When the babies hit their 30s, they were given an IQ test and asked about their incomes and education achievements (however, data was only available for 3,493 of the 5,914). Other variables were also examined, including family income, birth weight, delivery type and maternal age. For babies breastfed for at least a year, researchers discovered that those adults scored four points higher on IQ tests, went to school 0.9 years longer and earned $100 more a month than those were were breastfed for less than a month.

“The likely mechanism underlying the beneficial effects of breast milk on intelligence is the presence of long-chain saturated fatty acids (DHAs) found in breast milk, which are essential for brain development,” Dr. Horta says. “Our finding that predominant breastfeeding is positively related to IQ in adulthood also suggests that the amount of milk consumed plays a role.”

Now, despite the fact that I breastfed both my children well into toddlerhood—which would make them wealthy geniuses in 25 years—I’m skeptical of this study for two reasons:

  • As pointed out by The Atlantic’s Adrienne Lafrance, the research is flawed. Researchers were able to follow up with only 59 percent of the study participants, far below the 80-90 percent that most researchers say is the optimal follow-up rate. Lafrance also cites another study that suggests that reports are often inaccurate when it comes to asking women to recall how long they breastfed their child.
  • My husband was formula-fed in the early 1970s, long before many of the new advances in formulas that make it nutritionally closer to breast milk. He has three college degrees, a well-paying job and scores better on IQ test scores than me—a breastfed-baby. I simply find it hard to believe that formula-fed babies will not be as successful or as smart as breastfed babies.

I consider myself lucky to have been able to breastfeed my children successfully for as long as I did, but in no way do I attribute their intelligence to breast milk. Rather, it’s thoughtful and intuitive parenting that oftentimes comes with trusting your gut and ignoring the latest research.

Follow along as Jennifer Pinarski shares her experiences about giving up her big city job and lifestyle to live in rural Ontario with her husband, while staying home to raise their two young children. Read more Run-at-home mom posts or follow her @JenPinarski.