Maternal prenatal fish consumption and cognition in mid childhood: Mercury, fatty acids, and selenium

Background: Few studies of maternal prenatal fish intake have included biomarkers of exposure to mercury, long-chain n-3 fatty acids, and selenium, which are hypothesized to mediate associations with child neurodevelopment.

Objectives: Examine associations of maternal prenatal fish intake with child neurodevelopment accounting for biomarkers.

Methods: In 1999-2002 we enrolled pregnant women into the Project Viva cohort. At median 27.9weeks gestation, we estimated maternal fish intake using food frequency questionnaires, and collected blood. We assayed erythrocytes for total mercury and selenium, and plasma for fatty acids including n-3 docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). In mid-childhood (median 7.7years), we administered cognitive tests including the Kauffman Brief Intelligence Test (KBIT). We performed multivariable linear regression analyses adjusting for maternal and child characteristics including home environment and maternal intelligence.

Results: Among 1068 pairs (872 with blood), mean (SD) exposures were: maternal fish intake 1.7 (1.5)servings/week, mercury 4.0 (3.6)ng/g, DHA+EPA 98.4 (41.8)mcg/ml, selenium 205.6 (34.6)ng/ml. Child KBIT verbal scores (mean 112.2, SD 15.0) were not related to any exposures: maternal fish intake (0.15; 95% CI: -0.50, 0.79), mercury (0.08; -0.18, 0.35), DHA+EPA (0.01; -0.22, 0.24), and selenium (0.20; -0.09, 0.50). Associations with KBIT nonverbal scores and tests of memory and visual motor abilities were similarly null. Mutual adjustment for each of the exposure measures did not substantially change estimates.

Conclusions: In this population with an average fish consumption of about 1 1/2 weekly servings, we did not see any evidence for an association of maternal prenatal fish intake, or of mercury, DHA+EPA, or selenium status, with verbal or non-verbal intelligence, visual motor function, or visual memory at median 7.7years of age.