Researchers Call for Change in Guidelines About Eating Fish During Pregnancy

Findings from a new study in the United Kingdom suggest that it does not matter which types of fish are eaten during pregnancy, because essential nutrients found in fish could protect against the mercury content.

Although researchers have known for some time that the children of women who eat fish during pregnancy are likely to benefit in various ways, official guidelines have warned pregnant individuals against eating types of fish that have relatively high levels of mercury. As a result, some women may stop eating any fish as a precaution. The new research, however, suggests that protective nutrients in fish would protect against the mercury levels.

“We found that the mother’s mercury level during pregnancy is likely to have no adverse effect on the development of the child, provided that the mother eats fish,” said study co-author Caroline Taylor, PhD, in a press release. “If she did not eat fish, then there was some evidence that her mercury level could have a harmful effect on the child. This could be because of the benefits from the mix of essential nutrients that fish provides, including long-chain fatty acids, iodine, vitamin D, and selenium.”

Although several studies have considered this issue, the new research looked at 2 contrasting analyses of populations with mercury levels measured during pregnancy, in which the researchers followed up with the children at frequent intervals.

The first is a study focused on a population in the Seychelles, where nearly all pregnant women eat fish. The second study considered analyses of data from the University of Bristol’s Avon Longitudinal Study of Parents and Children, based in a relatively industrialized area in southwest England where fish are consumed less frequently. No summary of findings from the second study have been published before.

“It is important that advisories from health professionals revise their advice warning against eating certain species of fish,” said co-author Jean Golding, PhD, DSc, FSS, FFPHM, MRCPCH, F.Med.Sci, in the press release. “There is no evidence of harm from these fish, but there is evidence from different countries that such advice can cause confusion in pregnant women. The guidance for pregnancy should highlight ‘Eat at least 2 portions of fish a week, 1 of which should be oily’—and omit all warnings that certain fish should not be eaten.”

REFERENCE

Study calls for change in guidance about eating fish during pregnancy. News release. University of Bristol; September 6, 2022. Accessed September 12, 2022. https://www.bristol.ac.uk/news/2022/september/fish-pregnancy.html