Research links prenatal fish intake to reduced chance of autism, but not omega-3 supplements

04 Sep 2024 --- Eating any amount of fish during pregnancy was linked to a 16% lower likelihood of autism spectrum disorder diagnosis in offspring, specifically in girls, and a slight reduction in autism-related traits, according to new research. However, the team did not find the same association from consuming supplements containing omega-3 fatty acids. 

The study was funded by the Environmental influences on Child Health Outcomes (ECHO) Program at the US National Institutes of Health. 

Fish is an important source of omega-3, essential nutrients during pregnancy to support maternal health and child neurodevelopment. However, a recent ECHO study indicated that around 25% of pregnant participants reported eating fish less than once a month or not at all during their pregnancy, with even fewer people taking omega-3 supplements. 

“Our study contributes to a growing body of evidence demonstrating the role that prenatal diet can play in autism-related outcomes in offspring,” says ECHO cohort researcher Emily Oken, MD, MPH, of Harvard Medical School, US.

She adds that the research results underscore the need for better public health messaging about guidelines for fish consumption for pregnant people, considering the low fish intake in the US and the rising diagnoses of autism.

Fish or omega-3 intake

The study, published in The American Journal of Clinical Nutrition, analyzes data from 32 ECHO cohorts, where participants follow a common protocol to assess the effects of exposures on child-focused outcomes, including neurodevelopment. 

For the analysis of autism diagnosis, the researchers included 3,939 individuals for fish intake and 4,537 people for supplement consumption. The research on autism traits included 3,609 people for fish consumption and 3,925 for supplement use. 

The research includes information on children born between 1999 and 2019, with ongoing follow-up data until 2022. The team used self-reported dietary details on fish and omega-3 supplement consumption. 

The authors categorized fish intake as less than once a month, more than once a month, but less than weekly, weekly and two or more servings per week. Around 20% of adult participants reported no fish intake, and most reported not using omega-3 or fish oil supplements. 

Any amount of fish was linked to consistent results on autism diagnosis.Autism spectrum

Autism diagnosis was based on a parent or caregiver report of physician-diagnosed autism spectrum disorder. At the same time, the researchers assessed autism-related traits using the Social Responsiveness Scale (SRS), “one of the most widely used quantitative measures of the autism-related phenotype.” A higher score on this scale indicates the presence of more autism-related behaviors. 

Consuming fish during pregnancy was associated with a lower likelihood of offspring being diagnosed with autism and a lower total SRS score compared to not eating fish. 

The researchers note that these results were consistent across all levels of fish consumption, from “any” amount or “less than once per week” to “more than twice per week.” They found no significant associations between omega-3 fish oil supplement use and autism diagnosis. 

“This study provides yet more evidence for the safety and benefit of regular fish consumption during pregnancy,” details Oken. “Other proven benefits include lower risk for preterm birth and improved cognitive development.”

A recent report by the Global Organization for EPA and DHA Omega-3s cautions that pregnant women eat less fish than women who are not expecting. The review points to an FDA guidance on fish consumption, citing mercury contamination concerns as the possible source of this limited consumption. 

At the same time, it concludes that “regardless of mercury intake levels, the higher the fish intake, the better the cognitive performance of the offspring.”