Maternal fish consumption, hair mercury, and infant cognition in a U.S. Cohort.
Level 3 - non-randomized controlled study
Prospective cohort study
PubMed 16203250 · doi:10.1289/ehp.8041
What was done
The authors analyzed 135 mother-infant pairs from Project Viva, a prospective U.S. pregnancy and child cohort study, to examine the relationship of maternal second-trimester fish intake and delivery hair mercury levels with infant cognition. Infant cognitive development was assessed at 6 months of age via percent novelty preference on visual recognition memory (VRM) testing. Associations were evaluated using linear regression models adjusted for participant characteristics and mutually adjusted for fish intake and mercury exposure.
What was found
Mothers consumed an average of 1.2 fish servings per week during the second trimester, and mean maternal hair mercury was 0.55 ppm (10% > 1.2 ppm). Mean infant VRM score was 59.8 (range, 10.9-92.5). After adjusting for covariates and hair mercury, each additional weekly fish serving was associated with a 4.0-point higher VRM score (95% CI, 1.3 to 6.7). Conversely, each 1 ppm increase in hair mercury was associated with a 7.5-point decrement in VRM score (95% CI, -13.7 to -1.2). The highest VRM scores occurred in infants whose mothers consumed > 2 fish servings per week but had mercury levels <= 1.2 ppm.
Why it matters
This study demonstrates the opposing cognitive impacts of prenatal seafood consumption: beneficial nutritional components improve early infant cognition, while methylmercury contamination impairs it. The results support public health recommendations for pregnant women to consume fish with low mercury levels.
Limits
The sample size was modest (135 mother-infant pairs) from a single cohort, and infant cognition was measured only at 6 months using visual recognition memory rather than comprehensive or long-term neurodevelopmental assessments. Maternal fish consumption was self-reported, and residual confounding from other maternal dietary or socioeconomic factors remains possible.
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.