Maternal fish intake during pregnancy, blood mercury levels, and child cognition at age 3 years in a US cohort.
Level 3 - non-randomized controlled study
Prospective cohort study
PubMed 18353804 · doi:10.1093/aje/kwn034
What was done
Authors analyzed a prospective cohort of 341 mother-child pairs in Massachusetts enrolled between 1999 and 2002. They assessed maternal second-trimester fish intake and erythrocyte mercury concentrations. Child cognitive development was tested at age 3 years using the Peabody Picture Vocabulary Test (PPVT) and the Wide Range Assessment of Visual Motor Abilities (WRAVMA). Multivariable linear regression was used to evaluate associations with mutual adjustment for fish intake and mercury exposure.
What was found
Mean maternal fish intake was 1.5 (standard deviation, 1.4) servings/week, and 40 mothers (12%) consumed >2 servings/week. Mean maternal mercury was 3.8 (standard deviation, 3.8) ng/g. In mutually adjusted models, fish intake >2 servings/week versus never showed an effect estimate of 2.2 (95% CI: -2.6, 7.0) on the PPVT and 6.4 (95% CI: 2.0, 10.8) on the WRAVMA; intake of <=2 servings/week showed no benefit. Mercury in the top decile was associated with lower scores on both the PPVT (-4.5, 95% CI: -8.5, -0.4) and the WRAVMA (-4.6, 95% CI: -8.3, -0.9).
Why it matters
The findings demonstrate opposing influences of maternal seafood consumption during pregnancy, showing that nutritional benefits for child cognition coexist with negative impacts from mercury exposure.
Limits
The study is observational and prone to residual confounding. The sample of women consuming >2 servings of fish per week was small (n = 40). Exposure was assessed only in the second trimester, and results from a single regional cohort may not generalize to populations with different seafood diets or contamination levels.
Cited by
- contradicts Studies show that higher mercury levels, which reflect higher fish consumption, are associated with higher IQ scores in children due to the benefits of omega-3 fatty acids.