Associations of seafood and elongated n-3 fatty acid intake with fetal growth and length of gestation: results from a US pregnancy cohort.

Previous studies, mainly among populations with high consumption of seafood, have suggested that increased marine n-3 polyunsaturated fatty acid (PUFA) intake during pregnancy promotes longer gestation and higher birth weight. Few studies have isolated the contribution of fetal growth to birth weight. Using data from 2,109 pregnant women in Massachusetts enrolled in Project Viva from 1999 to 2002, the authors examined associations of marine n-3 PUFA and seafood intake with birth weight and birth-weight-for-gestational-age z value (fetal growth) using linear regression; length of gestation using median regression; and low birth weight, preterm delivery, and being small for gestational age using logistic regression. After adjustment for maternal and child factors, birth weight was 94 (95% confidence interval: 23, 166) g lower and fetal growth z value 0.19 (95% confidence interval: 0.08, 0.31) units lower in the highest compared with the lowest quartile of first-trimester n-3 PUFA intake. Results for the second and third trimesters were similar, and findings for seafood paralleled those for n-3 PUFA. Elongated n-3 PUFA intake and seafood intake were not associated with length of gestation or risk of preterm birth. Results from this US cohort support the conclusion that seafood intake during pregnancy is associated with reduced fetal growth.