Is fish a good thing during pregnancy?

U. ROCHESTER (US) — For pregnant women and their unborn babies, the good that comes from eating fish may outweigh the bad.

A new study adds to growing scientific evidence that while an expectant mother who eats fish exposes her child to the neurotoxin methyl mercury, but also boosts the baby’s brain development.

The Food and Drug Administration advises pregnant woman to eat only two meals of fish a week and to avoid most large fish to reduce exposing their babies’ developing brains to mercury. However, a recent joint report from the World Health Organization and the Food and Agriculture Organization of the United Nations recommended nations actually emphasize the benefits of eating fish for pregnant women and nursing mothers and the potential risks not consuming fish could have on the baby’s brain development.


These messages are confusing for consumers, which is why researchers are trying to sort out what happens to children’s development when their mothers eat fish while pregnant.

For the study, published in the Journal of Nutrition, researchers collected detailed information from 225 mothers about nutritional status and standard assessments on language and intelligence of their children over several years.

“This study shows that there are no adverse effects of prenatal mercury exposure from fish on children at 5 years old on 10 developmental outcomes when adjusted for maternal levels of polyunsaturated fatty acids. In fact, we found positive associations with those nutrients and children’s language development,” says Phil W. Davidson, professor emeritus of pediatrics at the University of Rochester and principal investigator of the ongoing Seychelles Child Development Study.

Women in the study, which was conducted in the Republic of Seychelles in the Indian Ocean, eat an average of 10 times as much fish as mothers in the US. The fish has about the same level of mercury as fish in the US. The children’s standard language development scores rose as levels of omega-3 fatty acids rose in mothers. These nutrients are important building blocks in the brain and are present in large amounts in fish. Fish are the primary dietary source of many of the fatty acids that play a crucial role in brain development.

“Based on our results, we would argue that the beneficial effects of fish consumption during pregnancy outweigh any adverse effects of methyl mercury,” says lead author Sean Strain, professor of nutrition at the University of Ulster in Northern Ireland.

The researchers found positive associations between the level of polyunsaturated fatty acids in mothers and their children’s subsequent scores on preschool language and verbal assessments. In particular, those scores were associated with DHA, an omega-3 fatty acid.

“The potential interplay of mercury and polyunsaturated fatty acids from fish appears very complex and we are just beginning to understand their relationship. It may be that polyunsaturated fatty acids impact the inflammation or oxidation that mercury causes in the brain,” says Gary Myers, professor of neurology, environmental medicine and pediatrics at University of Rochester Medical Center, child neurologist, and a researcher on the Seychelles Child Development Study team.

Source: University of Rochester