Eat Seafood While Pregnant: All Benefits, No Harm Found in Body of Evidence Says Renown Harvard Professor

In a recent editorial in The American Journal of Clinical Nutrition, “Fresh fish findings?,” Dr. Emily Oken of Harvard Medical School responds to a new study in the journal and summarizes the total body of evidence on seafood during pregnancy and the impact on child brain development. She concludes that fish consumption by pregnant women is beneficial for baby brain development and shows no harm, and more observational studies demonstrating benefits or lack of harm from prenatal fish consumption will likely not contribute fresh knowledge to this topic.

The editorial was printed alongside a new paper, “Maternal dietary intake of fish and PUFAs and child neurodevelopment at 6 months and 1 year of age: a nationwide birth cohort—the Japan Environment and Children’s Study (JECS),” by Dr. Kei Hamazaki. It found “maternal fish intake during pregnancy was independently associated with reduced risk of delay in problem-solving at age 6 [months] and in fine motor skills and problem-solving at age 1 [year].” The study also found, as summarized by Oken, “None of the results suggested harm from higher fish consumption.”

“These results nicely confirm what we already know,” she continued.

“Eating seafood by moms before, during and after pregnancy is beneficial for neurocognitive development for the baby,” says Dr. Tom Brenna, professor of pediatrics, of chemistry and of nutrition at the Dell Medical School, University of Texas at Austin and a co-author in a paper Oken repeatedly cites as evidence. “Consistent and strong studies demonstrate benefits and lack of harm at consumption levels well above 12 ounces per week.”  

The systematic review by Brenna and colleagues that is cited shows children can gain an average of 7.7 full IQ points from maternal seafood consumption. Benefits to neurocognitive development began at the lowest amounts of seafood consumed in pregnancy (one serving or about 4 oz. per week) and some studies looked at greater than 100 oz. per week. No adverse effects from seafood consumption were found for neurocognition in any of the publications.

Oken supposes that it is fish consumption and not just supplementation or omega-3s alone that offer the neurocognitive benefits. “Fish are rich in iodine, selenium, vitamin D, and other beneficial nutrients,” she writes. “Just like fruits and vegetables appear to provide health benefits that antioxidant supplements do not, it may be that seafood is more than a delivery system for” omega-3s.