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The Boston Globe

Health & wellness

Daily Dose

Mercury levels and ADHD behaviors

Pregnant women are often faced with a conundrum about whether to consume fish to help aid fetal brain development or to avoid it because certain fish can contain high levels of brain-damaging mercury, but a new study of children from the New Bedford area could help guide them.

Researchers from Brigham and Women’s Hospital and the Harvard School of Public Health found that children born to women who had high levels of mercury soon after giving birth were more likely to exhibit signs of attention deficit hyperactivity disorder in school by age 8.

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On the flip side, the children whose mothers consumed the most fish while pregnant were the least likely to exhibit fidgety, distracted, and impulsive behaviors in class, according to the study of 604 children published last Monday in the Archives of Pediatrics and Adolescent Medicine.

At first blush, this finding appears contradictory because most of the mercury we consume comes from fish. But, “fish consumption doesn’t necessarily correlate with mercury levels since you could eat a high amount of fish that are low in mercury,” said study coauthor Dr. Susan Korrick, an assistant professor of medicine at Brigham and Women’s Hospital.

The key is for pregnant women to avoid fish known to have high mercury levels, including swordfish, shark, tilefish, and king mackerel, Korrick added. Instead, they might want to aim for three or four servings of low-mercury fish such as salmon, canned light tuna, haddock, cod, and shrimp.

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