Eating This Way in Pregnancy May Increase Autism Risk by 122%

New research from Denmark suggests that a mother’s diet during pregnancy—specifically a Western-style diet high…

New research from Denmark suggests that a mother’s diet during pregnancy—specifically a Western-style diet high in fat and sugar but low in fresh, whole foods—may contribute to an increased risk of neurodevelopmental disorders, including ADHD and autism, in children. Researchers highlight the potential for dietary interventions during pregnancy to help reduce this risk.

Smoking, alcohol consumption, and poor diet have long been recognized as factors affecting fetal development. Now, a comprehensive clinical study from the University of Copenhagen and the Copenhagen Prospective Studies on Asthma in Childhood (COPSAC) at the Danish Paediatric Asthma Centre, Herlev and Gentofte Hospital, has identified a link between a mother’s diet during pregnancy and the likelihood of her child developing ADHD or autism.

“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,” says lead author, Dr David Horner, MD, PhD.

The study used data-driven analysis to identify a Western dietary pattern and its impact on neurodevelopmental risks. Even moderate shifts toward this diet were linked to significantly higher risks. Specifically, a slight move toward a Western diet was associated with a 66% increased risk of ADHD and a 122% increased risk of autism. However, this also suggests a potential benefit: even small dietary changes away from a Western pattern may help lower the risk of these neurodevelopmental disorders.

Over 60,000 Mother-Child Pairs Analysed

To reach these findings, researchers analyzed dietary patterns, blood samples, and ADHD diagnoses across four large independent cohorts in Denmark and the United States, encompassing more than 60,000 mother-child pairs. Blood samples were analyzed using metabolomics, providing insights into the biological mechanisms linking diet to neurodevelopmental disorders and serving as a validation method for the results.

The link between Western dietary patterns and ADHD was observed across all four cohorts and validated in three of them using three different methods, reinforcing the study’s credibility, according to David Horner.

The study draws on a highly detailed and robust dataset where nearly 600 children were clinically assessed for neurodevelopmental disorders at age 10. To ensure the reliability of the findings, researchers accounted for a range of factors, including genetics, which is known to play a major role in neurodevelopmental disorders. Yet, a clear association between a maternal Western diet and the risk of ADHD and autism remained.

The study was recently published in the journal Nature Metabolism.

Greatest Risk in Early Pregnancy

One of the key strengths of this study is the high quality of the biological samples, which included repeated metabolomic measurements throughout pregnancy and childhood. This allowed researchers to demonstrate that the association between diet on ADHD risk was strongest in early and mid-pregnancy.

“When comparing across cohorts, 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,” explains senior author Professor Morten Arendt Rasmussen from the University of Copenhagen.

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

“We found that 15 of these 43 metabolites were particularly linked to the increased risk of ADHD. 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,” says David Horner.

Are Current Dietary Guidelines for Pregnant Women Effective?

According to David Horner, this study raises important questions about whether current dietary guidelines for pregnant women are sufficient.

In Denmark, dietary recommendations for pregnant women largely mirror those for the general population, emphasizing a balanced diet rich in vegetables, fruit, whole grains, and fish rather than red meat.

“We know that nutritional demands increase during pregnancy, and our study highlights just how crucial dietary composition is for fetal development. 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. This study raises the question of whether existing dietary recommendations are sufficiently followed during pregnancy—and whether they have the desired impact on child health,” says David Horner.

He adds that the study not only demonstrates an association between diet and ADHD risk but also provides insights into specific nutrients and food groups that could play a vital role in fetal brain development.

“Our analysis not only confirms a strong link between diet and ADHD risk but also identifies specific nutrients and foods that could serve as the foundation for improved dietary guidelines and preventative strategies. By understanding how maternal diet influences fetal development, we can better identify the key nutrients and dietary adjustments needed to reduce the risk of neurodevelopmental disorders. This opens new possibilities for refining dietary recommendations and promoting healthier outcomes for future generations.”

Key Findings:

The study finds a strong association between a Western dietary pattern during pregnancy and an increased risk of neurodevelopmental disorders, including ADHD and autism.

Findings for ADHD were validated in 3 independent mother-child cohorts.

The strongest associations between a Western diet and ADHD risk were observed in the first and second trimesters, suggesting that fetal brain development during this period is particularly sensitive to maternal nutrition.

Methodology:

Researchers used a combination of dietary records, blood analyses, genetic data, and clinical diagnoses from four large mother-child cohorts to investigate whether a Western diet during pregnancy was associated with an increased risk of ADHD and autism in children.

The Four Cohorts Analysed:

COPSAC2010 (Denmark, 508 mother-child pairs) – Primary cohort with detailed neurodevelopmental clinical assessments at 10 years, and five metabolomics time points in both mother and child, as well as fetal dry blood spot metabolomics.
Danish National Birth Cohort (DNBC, Denmark, 59,725 mother-child pairs) – Large population-based study used to validate FFQ-based dietary patterns against ADHD diagnoses in national registers.
VDAART (USA, 656 mother-child pairs) – Used to validate dietary patterns and blood metabolites from both pregnancy and childhood in relation to ADHD.
COPSAC2000 (Denmark, 348 mother-child pairs) – Used to analyze fetal dry blood spot metabolomes to identify a metabolic signature of a Western dietary pattern and validate its link to ADHD symptoms.

Limitations:

This is an observational study, meaning it shows a strong statistical association but does not conclusively prove that a Western diet causes ADHD or autism.

Dietary information was collected through self-reported food frequency questionnaires (FFQ), which may introduce recall bias and inaccuracies.
However, dietary patterns were identified using data-driven methods (minimizing bias), and machine-learning models were employed to identify metabolite scores as an objective biomarker.
Genetics also plays a major role. ADHD and autism have a high genetic component (up to 80% heritability).
Women with a more Western diet often had higher BMI, smoked during pregnancy, and used more antibiotics, which may independently affect child development. The study adjusted for these factors but cannot fully rule out other lifestyle influences.

Reference: “A western dietary pattern during pregnancy is associated with neurodevelopmental disorders in childhood and adolescence” by David Horner, Jens Richardt M. Jepsen, Bo Chawes, Kristina Aagaard, Julie B. Rosenberg, Parisa Mohammadzadeh, Astrid Sevelsted, Nilo Vahman, Rebecca Vinding, Birgitte Fagerlund, Christos Pantelis, Niels Bilenberg, Casper-Emil T. Pedersen, Anders Eliasen, Sarah Brandt, Yulu Chen, Nicole Prince, Su H. Chu, Rachel S. Kelly, Jessica Lasky-Su, Thorhallur I. Halldorsson, Marin Strøm, Katrine Strandberg-Larsen, Sjurdur F. Olsen, Birte Y. Glenthøj, Klaus Bønnelykke, Bjørn H. Ebdrup, Jakob Stokholm and Morten Arendt Rasmussen, 3 March 2025, Nature Metabolism.
DOI: 10.1038/s42255-025-01230-z