DUBLIN — A major new study conducted by researchers at the University College Dublin (UCD) appears to have debunked a central claim advanced by advocates of breastfeeding –– that the practice boosts your child’s “intelligence” level.

The Irish research team, led by Dr. Lisa-Christine Girard of the UCD School of Public Health, Physiotherapy and Sports Science, examined the effects of breastfeeding on children’s cognitive abilities, including problem-solving and vocabulary, at ages three and five. They also tested whether breastfed children tended to display less hyperactivity.

To their surprise, only the effects of breastfeeding on hyperactivity were statistically significant – but they were also relatively weak. By age 5, there was no difference in the level of hyperactivity between children who breastfed and those that drank artificial bottled milk, the researchers found.

As for “intelligence,” once the researchers controlled for socio-economic status and other variables, there was no statistically significant difference at all between the two groups. Even prolonged breastfeeding – beyond six consecutive months between ages 3 and 5 — had no appreciable impact on an infant’s vocabulary or problem-solving abilities.

“We weren’t able to find a direct causal link between breast-feeding and children’s cognitive outcomes,” Girard told a National Public Radio interviewer.

The Irish team’s provocative findings do nothing to undermine past studies concluding that prolonged breastfeeding can reduce the incidence of infectious diseases in newborns as well as lower their risk of developing diabetes or cancer in adulthood.

But the study, published in the April 2017 issue of the journals Pediatrics, flatly contradicts a spate of studies, including one published in 2013, which found that breastfeeding improved infant cognitive abilities, including early comprehension of language and enhanced verbal and nonverbal IQ at school age.

Girard’s team drew on an unusually large and robust sample of children – nearly 8,000 — who formed the infant cohort of a larger longitudinal study known as “Growing Up in Ireland.” The children were tested using psychometric scales at age 3 and again at age 5 to assess their cognitive and emotional development. Girard’s team also drew on parental and teacher reports to gain deeper insights into the status of individual cases.

Their findings probably won’t do much to change the way many Irish women feed their babies. The country has one of the lowest breastfeeding rates in the world – just 56%. But many professional women that do not consistently breastfeed – citing workplace and societal pressures — have suffered something of a backlash from mothers that do, and from conservative ideologues who see their refusal as a lack of commitment to “motherhood.”

After this new study, today’s “Mommy Wars” may never be the same.