Pregnant mothers who take omega-3 fatty acid supplements to boost their baby’s brain power are probably wasting their time, according to a major Australian study.

Researchers found no benefit after following more than 600 children from before they were born until the age of four.

There was no difference in the cognition, language or motor scores of children whose mothers took supplements and those who were given a placebo, according to the study published in the Journal of the American Medical Association (JAMA).

“Given the amount of marketing that occurs around the use of fish oil supplements for brain development, these are significant findings,” says study leader Professor Maria Makrides of the South Australian Health and Medical Research Institute and the University of Adelaide.

The study did not test other health benefits of omega-3 fatty acids.

In the study, pregnant women received either DHA – an omega-3 fatty acid – supplements or a placebo.

The researchers found no difference in the two groups at 18 months.

In a follow-up at four years, the children were tested for differences in cognition, the ability to perform complex mental processing, language and executive functioning such as memory, reasoning and problem solving.

Again, there was no significant difference.

“Our research does not support prenatal DHA supplementation to enhance early-childhood development,” Prof Makrides says.