Optimal neurodevelopment of the fetus depends in part on an adequate supply of docosahexaenoic acid (DHA), an omega-3 essential fatty acid that is abundant in seafood. A diet lacking in seafood could impair development because of too little long-chain omega-3 fatty acids such as DHA and eicosapentaenoic acid. Nevertheless, federal agencies have recommended limiting seafood consumption by parturients to 340 g per week so as to avoid exposing the fetus to trace amounts of neurotoxins. The investigators used data from the Avon Longitudinal Study of Parents and Children to clarify the influence of maternal seafood intake during pregnancy on developmental, behavioral, and cognitive outcomes at ages 6 months to 8 years. Participating were 11,875 pregnant women who completed a food frequency questionnaire at 32 weeks’ gestation. Children were assessed using items from the Denver Developmental Screening Test as well as the Strengths and Difficulties Questionnaire and verbal and performance intelligence quotient (IQ) scores.
About one-third of women in the study ate up to 340 g of seafood each week, whereas 12% ate no seafood at all while pregnant. Just under one-fourth of women ate more than 340 g weekly. Low seafood consumption correlated with a socially disadvantageous setting including low educational levels and also with less than ideal lifestyles. After adjusting for these and other variables, eating less than 340 g of seafood each week correlated with an increased likelihood of a verbal IQ in the lowest quartile. The odds ratio (OR) for women eating no seafood, compared with those eating more than 340 g weekly, was 1.48 with a 95% confidence interval (CI) of 1.16–1.90. For women eating some seafood but less than 340 per week the OR for low verbal intelligence was 1.09 (95% CI, 0.92–1.29). Low seafood intake also was associated with suboptimal outcomes for prosocial behavior, fine motor function, communicative ability, and social development scores. In each instance, the risk of a suboptimal outcome increased with declining levels of seafood intake. Fewer than 2% of women in this study consumed fish oil supplements while pregnant. Outcomes of infants whose mothers took a supplement but did not eat seafood were similar to those in infants whose mothers did eat seafood. No trend toward benefit in any neurodevelopmental domain was observed when the weekly seafood intake was less than 340 g.
These findings suggest that limiting weekly seafood consumption to less than 340 g may have adverse effects on early childhood neurodevelopment. The authors believe that a lack of essential nutrients is more harmful than potential exposure to the trace contaminants present in some seafood.
Laboratory of Membrane Biophysics and Biochemistry, US National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Bethesda, Maryland; University of Illinois at Chicago; and Department of Community Based Medicine, University of Bristol, United Kingdom