Study: Breastfeeding Helps Protect Mothers from Cancer

(CNN) -- According to new research, the amount of time a baby is breastfed can have an impact on their test scores as a teenager.

The report, published Monday in the journal Archives of Disease in Childhood, followed about 5,000 British children from infancy in the early 2000s to their final year of secondary school, according to the study's lead author, Dr. Reneé Pereyra-Elias, a PhD student and researcher at the National Unit for Perinatal Epidemiology at the University of Oxford.

The children were divided into groups based on how long they were breastfed — nothing, a few months or for a year or more, according to the study. The researchers then compared the children's results on the UK General Certificate of Secondary Education tests in their final years of secondary school.

What the study team found was that there was a modest improvement in test scores associated with being breastfed longer, Pereyra-Elias said.

Compared to those who never breastfed, children who were breastfed for at least 12 months were 39% more likely to pass the GCSE maths and English exams and 25% less likely to fail the English exam.


But that doesn't mean every family should breastfeed their child, Pereyra-Elias said.

Not all families can breastfeed, and those who don't shouldn't be ashamed or feel guilty that they're putting their children at a disadvantage, she said.

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The analysis is careful and especially strong because of its sample size, said Kevin McConway, emeritus professor of applied statistics at England's Open University.

"While the results are certainly interesting, there are limitations to be taken into account that inevitably arise in research using observational data from major cohort studies," added McConway, who was not involved in the research.

The Link Between Breastfeeding and Test Scores

The fact that the study was observational means it followed people's behavior rather than randomly assigning the behavior in question, McConway noted.

Consequently, the results only show a correlation between breastfeeding and test scores, not causation. "It's not possible to be sure what's causing what," he said.

In the United Kingdom, mothers who have a higher socioeconomic position are more likely to breastfeed their children, and their children are more likely to do well in school, McConway said.

"That doesn't mean it's breastfeeding that makes kids do well in school; Obviously, it could be some other aspect of the fact that his family is doing relatively well," he added.

It could be that something about breastfeeding makes children more likely to do well on their exams, but it could also be that another independent factor influences both the child's chances of being breastfed and their tests, McConway said.

The researchers tried to control for many factors that could influence their results, such as the mother's cognitive ability, but couldn't explain everything in an observational study. "There may be some confounding factors. We did the best we could," Pereyra-Elias said.

The benefits of breastfeeding

The study showed the test results as one of many possible benefits of breastfeeding, said Dr. Andrew Whitelaw, professor emeritus of neonatal medicine at the University of Bristol, England. Whitelaw was not involved in the investigation.

The difference this study showed was modest, Pereyra-Elias added, meaning it doesn't make a big enough difference in test scores to worry parents, Pereyra-Elias said.

The bottom line is that families in general should be encouraged to breastfeed because of the multiple possible benefits, but that it still may not be in the best interest of each individual family, she said.

And more studies are needed to confirm the findings, especially those that take into account variables between families, Pereyra-Elias said.

"Although these questions have been around for nearly a century, we still don't have a definitive answer," he said.