A mother’s diet during pregnancy can influence her child’s risk of ADHD and autism, a new study says.

In particular, the unhealthy hallmarks of a typical Western diet appeared to increase a child’s risk of developmental disorders, researchers reported in the journal Nature Metabolism.

“The greater a woman's adherence to a Western diet in pregnancy - high in fat, sugar, and refined products while low in fish, vegetables, and fruit — the greater the risk appears to be for her child developing ADHD or autism,” lead researcher Dr. David Horner of the University of Copenhagen in Denmark said in a news release.

Even slight moves toward a more Western diet were linked to a 66% increased risk of ADHD and a 122% increased risk of autism, researchers found.

But this also means that even small dietary adjustments away from a Western pattern of eating could potentially reduce a child’s risk of developmental disorders, researchers added.

For this study, researchers started by identifying more than 500 Norwegian 10-year-olds diagnosed with a developmental disorder, and then analyzed what their moms ate during pregnancy.

In that group, they found significant associations between an expecting mother’s diet and later ADHD and autism diagnoses among their children.

The team then tested those associations in larger groups of mother-child pairs, ultimately analyzing more than 60,000 Norwegian mothers and their kids.

Researchers found that the link between diet during pregnancy and developmental risk in children held firm.

“We observed the strongest associations in the first and second trimesters, suggesting that brain development during this period is particularly sensitive to maternal nutritional influences,” senior author Morten Arendt Rasmussen, a professor of food microbiology, gut health and fermentation at the University of Copenhagen, said in a news release.

Researchers identified 43 specific metabolites in maternal blood that were linked to a Western diet and could help explain the link between diet and neurodevelopmental disorders.

“We found that 15 of these 43 metabolites were particularly linked to the increased risk of ADHD,” Horner said. “Many of these metabolites are derived from dietary intake and play key roles in regulating inflammation and oxidative stress — factors believed to be critical in early neurodevelopment.”

These results call into question whether the current dietary recommendations for pregnant women are sufficient, given that they tend to largely mirror those of the general population, Horner said.

“We know that nutritional demands increase during pregnancy, and our study highlights just how crucial dietary composition is for fetal development,” Horner said. “While the Nordic diet is often considered healthy, our data show that many pregnant women follow dietary patterns that could be optimized to better support their child’s development.”

He said the study raises the question of whether existing dietary recommendations are followed sufficiently during pregnancy and whether the guidelines have the desired impact on child health.