Studies in countries with high seafood consumption have shown a benefit on fetal growth and child development. The objective of our study was to determine the association between seafood consumption in French pregnant women and fetal growth. Pregnant women included in the EDEN mother-child cohort study completed two food frequency questionnaires on their usual diet in the year before and during the last 3 months of pregnancy (n = 1805). Fetal circumferences were measured by ultrasound and anthropometry at birth. Variables were compared across tertiles of the mother's seafood consumption using multiple linear regression to adjust for confounding variables. Analyses were stratified by maternal overweight status because of an interaction between maternal seafood consumption and her body mass index (P < 0.01). There was no association between seafood intake and fetal growth in the whole sample of women. For overweight women (n = 464), higher consumption of seafood before pregnancy was associated with higher fetal biparietal and abdominal circumferences and anthropometric measures. From the lowest to the highest tertiles, mean birthweight was 167 g higher (P = 0.002). No significant association was found with consumption at the end of pregnancy. In conclusion, high seafood consumption before pregnancy is positively associated with fetal growth in overweight women.