Seafood for Thought: The Role of Prenatal Fish Consumption on Autism Diagnosis

The Food and Drug Administration (FDA), the Environmental Protection Agency (EPA) and the Dietary Guidelines for Americans recommend that pregnant people eat at least two to three servings (about eight to 12 ounces) of a variety of seafood a week to obtain the important nutrients that aid in the baby’s brain development. However, prenatal fish consumption in the U.S. is generally low.

Led by researchers from Drexel University’s A.J. Drexel Autism Institute, Harvard Medical School and Harvard Pilgrim Health Care Institute, a recent study aimed to examine associations of prenatal fish consumption and omega-3 supplement use with autism diagnosis and broader autism-related traits in children. The NIH Environmental Influences on Child Health Outcomes (ECHO) program sponsored research was recently published in The American Journal of Clinical Nutrition.

“Studies examining how both prenatal fish consumption and omega-3 supplement use are associated with autism spectrum disorder (ASD) and related traits are lacking,” said Kristen Lyall, ScD, an associate professor in the A.J. Drexel Autism Institute and co-author of the study.

The study results showed a continuation of previous work that suggests that prenatal fish consumption, but not omega-3 supplement use, may be associated with a lower likelihood of both autism diagnosis and related traits. Lyall and co-author Emily Oken, MD, a professor in Harvard Medical School and Harvard Pilgrim Health Care Institute, added that given the low fish intake in the United States general population and the rising autism prevalence, these findings suggest the need for better public health messaging regarding guidelines on fish intake for pregnant individuals.

“This study provides yet more evidence for the safety and benefit of regular fish consumption during pregnancy,” said Oken. “Other proven benefits include lower risk for preterm birth and improved cognitive development. Pregnant people should aim to consume a variety of fish types at least twice weekly.”

The study also showed that the associations of fish intake and lower autism prevalence were somewhat stronger for female children. However, the associations did not show a dose-response pattern, suggesting a possible threshold effect of fish intake or the role of other nutrients in fish. Additionally, intake of supplements containing fish oil/omega-3 fatty acids during pregnancy was not associated with autism diagnosis or autism-related traits.

Researchers examined maternal fish consumption of 10,800 pregnant people, enrolled in 23 ECHO research sites, and omega-3/fish oil supplement use of 12,646 pregnant participants, at 35 ECHO research sites, for associations with clinician-diagnosed autism and parent-reported autism-related traits measured by parents or caregivers with the Social Responsiveness Scale (SRS)-Second Edition. Information on fish consumption and omega-3 supplement use was collected from pregnant participants between 1999 to 2020.

Analysis of the ECHO Cohort data found that around a quarter of the pregnant participants reported no fish intake during pregnancy. Even fewer participants reported taking omega-3 supplements.

Lyall and Oken said that the study suggests the need for continued public health efforts to encourage fish intake during pregnancy, accounting for types of fish with the lowest risk of toxicants (like mercury), and that the study supports the role of prenatal diet in autism-related outcomes in children.

Launched in 2016, the Environmental influences on Child Health Outcomes (ECHO) Program is a research program in the Office of the Director at the NIH with the mission to enhance the health of children for generations to come. ECHO investigators study the effects of a broad range of early environmental influences on child health and development. For more information, visit echochildren.org.