HealthDay News — Pregnant women who consume a lot of fish may not harm their unborn children, despite mercury exposure concerns, results of a study published in the American Journal of Clinical Nutrition suggest.

“Fish is a rich source of n–3 polyunsaturated fatty acids (PUFAs) but also contains the neurotoxicant methyl mercury (MeHg),” noted Edwin van Wijngaarden, PhD, an associate professor in the University of Rochester’s department of Public Health Sciences in Rochester, N.Y., and colleagues.

“PUFAs may modify the relation between prenatal MeHg exposure and child development either directly by enhancing neurodevelopment or indirectly through the inflammatory milieu.”

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To investigate the associations of prenatal MeHg exposure and maternal PUFA status with child development at age 20 months, the scientists followed 1,265 mothers and their children who were enrolled in the Seychelles Child Development Study Nutrition Cohort 2.

At age 20 months, the children underwent a battery of tests designed to measure their communication, behavior, and motor skills. Mothers provided hair samples during pregnancy to measure levels of prenatal mercury exposure.

Mercury exposure did not correlate with lower test scores, the researchers found, and some of the Seychelles children now have been observed living healthy, normal lives into their 20s. Mercury ended up associated with developmental damage only in children whose mothers had high levels of meat-related omega-6 fatty acids but low levels of omega-3s from fish oil.

“The theory is that mercury exposure confers toxicity because it induces oxidation in the human body, which often results in inflammation,” van Wijngaarden told HealthDay.

“These omega-3s are more anti-inflammatory. The idea would be that they would reduce the level of inflammation in the mother, softening any effect that mercury might have on the unborn child.”


  1. Van Wijngaarden E et al. Am J Clin Nutr. 2015; doi: 10.3945/​ajcn.114.100503