Could Eating Fish During Pregnancy Be Beneficial?

While the issues long thought to be associated with mercury exposure have led to FDA recommendations that suggest limited consumption of fish for pregnant women, a new study finds that eating fish may provide benefits that outweigh mercury-related risks for mother and child.

In a study of more than 1,500 mothers and children, a team including researchers from Ulster University and the University of Rochester Medical Center assessed childrens’ development using a variety of communication skills, behavior, and motor-skills tests, starting at 20 months after birth and following the children into their 20s. The authors also collected hair samples from the expectant mothers participating in the study, in order to measure prenatal mercury exposure levels.
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The researchers found no connection between prenatal mercury exposure and lower test scores, nor did they determine a link between pregnant womens’ fish consumption and impaired neurological development in their children as they were followed into their adult years. Levels of polyunsaturated fatty acids (PUFA) were measured in the pregnant women as well, with the authors finding that children of those with higher levels of the omega-3 fatty acid found in fish performed better on some of the administered tests.

“The problem with current dietary advice for pregnancy in most countries is that, even though some advisories emphasize the beneficial effects of fish, there remain warnings about the dangers of methyl-mercury in fish to the developing fetal brain,” says Sean Strain, PhD, BSc, BAgr, professor of human nutrition at Ulster University and lead author of the study.

“A risk will always trump a benefit, and the advice often makes women decrease their fish consumption further from an already low base.”

Strain and his co-authors, however, argue that “the benefits of fish consumption outweigh any risks.”

The risks of pregnant women eating fish “was largely identified from studies undertaken last century in the Faroe Islands,” continues Strain, “where the major contributor of dietary mercury was from pilot whale consumption—not fish—and the dietary intake of the population there was very traditional, as the study was undertaken before the world became interested in food miles and competition among the major food supermarkets.”

Based on these recent findings, Strain and colleagues contend that “physicians should be much relaxed about the specific advice on fish consumption during pregnancy,” he says.

“Women should be advised to eat as much fish as they want with one proviso,” adds Strain. “Although the Seychellois women eat fish at almost every meal, those ocean fish with the highest methyl-mercury concentrations are rarely eaten. And whilst our findings would indicate no associations with very high overall mercury exposure from very high fish consumption, such fish consumption does not include the top predatory fish, and certainly no whales or dolphins.”

—Mark McGraw

Reference

Strain J, Yeates A, et al. Prenatal exposure to methyl mercury from fish consumption and polyunsaturated fatty acids: associations with child development at 20 mo of age in an observational study in the Republic of Seychelles. Am J Clin Neutr. 2015.