Could breastfeeding lay the groundwork for good grades in high school?

That's what the findings of a new British study suggest, although the differences were small between those who were breastfed and those who weren't when it came to standardized test scores and grades.

"Breastfeeding promotes the development of the brain, which may account for better school performance," said lead researcher Dr. Renee Pereyra-Elías, from the national perinatal epidemiology unit in the Nuffield Department of Population Health at the University of Oxford, in the United Kingdom.

"Although we see that those children breastfed for longer do better than those children who were not breastfed at all, however, and this is something important, the difference between those who were breastfed for long and those who are not is not massive," he said.

Pereyra-Elías added that this study can't prove that breastfeeding causes students to do better in school, only that there appears to be an association.

"When possible, and when women decide to breastfeed, it should be supported because it could maybe increase the marks of the child a little bit, but it has a lot of other benefits as well," he said. "But if the women cannot breastfeed they should not be worried that their children are going to do worse in school, because these differences are very modest."

For the study, Pereyra-Elías and his colleagues collected data on nearly 5,000 children born in the United Kingdom between 2000 and 2002 who were part of the Millennium Cohort Study. The children were followed up at ages 3, 5, 7, 11, 14, 17 and 22. The researchers linked these data to the National Pupil Dataset, which keeps records of students enrolled in English public schools.

Specifically, the research team looked at the correlation between performance on standardized tests in English and mathematics at age 16 and the length of time the child was breastfed.

About 33% of the participants were never breastfed, and the remainder were breastfed for different periods. Only about 10% were breastfed for at least 12 months, the findings showed.

Only 19% of children who were breastfed for at least 12 months failed their English test, compared with 42% of those who were never breastfed, the researchers found. Also, 29% of those who were breastfed for at least 12 months passed with an A or an A+, compared with 10% who had not been breastfed.

In math, 24% of children who were breastfed for at least 12 months failed their test, compared with 42% of those who were never breastfed. And 31% of those who had been breastfed for at least 12 months passed with an A or A+, compared with 11% among non-breastfed children, Pereyra-Elías said.

Overall, after taking factors such as the parent's income and education into account, the researchers found that the children who had been breastfed for at least a year were 39% more likely to pass both exams with high marks and 25% less likely to fail the English exam.

The report was published online June 5 in the Archives of Disease in Childhood.

One expert thinks the findings, although modest, are another reason why breastfeeding is so important in the development of the body and mind of infants.

"Breastfeeding has been shown to have several benefits for families and children," said Dr. Adi Katz, director of gynecology at Northwell Lenox Hill Hospital in New York City. "Whenever possible, parents should be encouraged to breastfeed and provided resources to do so, such as breastfeeding classes, lactation consultants, breast pumps and lactation rooms."