New study explores link between fish consumption in pregnancy and autism—here’s what experts say

As moms, we’re constantly thinking about how our choices during pregnancy can shape our children’s development. From prenatal vitamins to the debate about sushi (safe or not safe?), it can feel overwhelming. Now, a new study in the American Journal of Clinical Nutrition adds to the conversation: eating fish during pregnancy may be associated with developmental differences, including a 20% reduced likelihood of traits associated with autism spectrum disorder (ASD) in children.

For years, researchers have been exploring how prenatal nutrition shapes a child’s development, and fish has often been part of the conversation—loaded with omega-3 fatty acids like DHA, which support brain health. But this study breaks new ground by suggesting a connection between fish consumption during pregnancy and autism-related outcomes.

What this study found about fish and developmental traits

The U.S.-based ECHO study analyzed ≤32 cohorts of pregnant participants with children born before 2019, focusing on autism outcomes after age 3. Researchers observed that moms who consumed fish during pregnancy were more likely to report developmental outcomes associated with fewer autism-related traits in their children. Interestingly, eating more fish didn’t significantly increase the benefit, but the reduction in autism risk was more pronounced in daughters than in sons.

Dr. Kristen Lyall, the study’s lead author, tells Motherly, “We did see some evidence suggesting stronger effects of the association in female children as compared to male children. While this finding needs to be replicated, one possible explanation is if omega-3 fatty acids are specifically linked with reducing the likelihood of autism with co-occurring intellectual disability (and females are more likely to be diagnosed with autism with intellectual disability than without). There is also prior evidence linking these fatty acids to cognitive development and intellectual disability—further suggesting this could be a contributing factor to this finding.”

Researchers also found that children of moms who ate fish during pregnancy showed differences in traits commonly associated with autism, such as variations in social interaction and communication styles, compared to kids whose moms skipped the fish entirely.

Even more surprising? Omega-3 supplements, often marketed as a fish-free alternative for pregnant moms, didn’t show the same benefits. In fact, the study noted a slight increase in autism-related traits among children whose moms relied on supplements instead of fish.

Why fish is a key ingredient for neurodevelopment

Fish is rich in nutrients, like DHA and selenium, which support overall brain health and development. These nutrients may work together to support healthy neurodevelopment in ways that supplements alone can’t replicate.

So why don’t supplements measure up? Dr. Lyall suggests, “One [reason] may be that the bioavailability of the long-chain fatty acids may differ in supplements than in the natural whole food. Another may be that other nutrients in fish, such as vitamin D, iron, or others, or its overall health benefits in being rich in protein, may contribute to positive neurodevelopment. A final—though speculative—possible reason is that other additives in supplements may counteract the benefits of the omega-3 fatty acids.”

Related: New study finds no link between acetaminophen use during pregnancy and autism and ADHD

What about mercury?

If you’re nervous about fish because of mercury, you’re not alone. This has been a hot topic for years, with many pregnant moms avoiding fish altogether to steer clear of potential risks. But according to this study, the benefits of moderate fish consumption outweigh the risks, as long as you stick to low-mercury options like salmon, sardines, and trout.

Related: Yes, you can eat fish while pregnant—study offers new info about pregnancy & mercury exposure

High-mercury fish like shark, swordfish, and king mackerel are still on the “avoid” list for pregnant moms. For moms still concerned about mercury, consulting your doctor or using guides like the FDA’s fish recommendations can help you make safe, informed choices.

What does this mean for moms-to-be?

While this study doesn’t suggest fish consumption prevents autism or guarantees specific developmental outcomes—ASD arises from a complex mix of genetic and environmental factors—it highlights how prenatal nutrition might play a role in developmental outcomes.

This research also raises questions about whether supplements can really match the benefits of whole foods. For pregnant moms, it’s a gentle nudge to revisit what’s on your plate and consider safe, moderate fish consumption as part of a well-rounded prenatal diet.

Dr. Lyall summarized, “I think our findings broadly support current dietary guidelines—that is, to consume at least 1–2 fish meals per week—and the overall benefits of fish consumption. Pregnant persons should follow guidelines regarding choosing types of fish low in mercury.”

The bottom line

This study provides more insight into how prenatal nutrition might influence child development. For moms-to-be, it’s a reminder that safe, moderate fish consumption can be a valuable part of a balanced prenatal diet. Always consult your healthcare provider to determine the best nutritional approach for you and your baby.

Sources:

1. Fish consumption during pregnancy and baby’s autism. The American Journal of Clinical Nutrition. 2024. “Association of maternal fish consumption and ω-3 supplement use during pregnancy with child autism-related outcomes: results from a cohort consortium analysis”