Seafood consumption in pregnancy and infant size at birth: results from a prospective Spanish cohort.

Background: Studies on maternal seafood consumption during pregnancy and the risk of small for gestational age (SGA) births have yielded inconsistent results. As few studies have examined associations with specific seafood subtypes or accounted simultaneously for exposure to persistent organic pollutants (POPs), it is uncertain to what extent intakes of seafood subtypes with variable contaminant or fatty acid content may explain these inconsistencies.
Methods: A cohort of 657 women recruited during the first trimester of pregnancy from a Mediterranean area with high seafood intakes was followed through birth. Dietary intakes were estimated using a validated questionnaire. Multivariable logistic regression was used to estimate associations between SGA and intakes of fatty fish, lean fish, canned tuna, crustaceans and other shellfish, adjusting for parity, child sex, parental anthropometry, socio-economic factors and serum levels of several POPs, including several polychlorinated biphenyls (PCBs), hexachlorobenzene (HCB) and dichlorodiphenyldichloroethylene (DDE).
Results: Overall, 7.8% of infants were SGA. Maternal consumption of crustaceans (more than once/week) and canned tuna (more than once/week was associated with a significantly increased risk of SGA. Fatty fish (more than once/week) was associated with weaker and generally non-significant increases in risk, while lean fish and other shellfish were not associated with SGA. Adjusting for contaminants did not meaningfully change results.
Conclusions: Higher maternal intakes of crustaceans and canned tuna, but not other types of seafood, were associated with increased risk of SGA independently of several POPs. Future studies exploring seafood subtypes and additional contaminants are needed to determine whether these associations are causal and identify mechanisms involved.