LAUSR

BACKGROUND & AIMS Maternal fatty acids are essential for fetal growth and development. Here, we examine associations between maternal mid-pregnancy plasma n-3 and n-6 polyunsaturated fatty acids (PUFAs) and fetal health determined by fetal growth velocity, birth weight and duration of pregnancy. METHODS Participants were 6974 pregnant women and their infants from a population-based birth cohort, the Generation R Study. Maternal plasma n-3:n-6 PUFA ratio and n-3 and n-6 PUFA percentage in glycerophospholipids in mid-pregnancy were related to fetal growth velocity calculated from repeatedly measured weight, length and head circumference, birth weight, and duration of pregnancy. RESULTS A higher maternal mid-pregnancy n-3:n-6 PUFA ratio was associated with a higher growth velocity of the fetal weight (β = 0.082 SD-score/week, 95% CI 0.055; 0.108, P < 0.001), length (β = 0.085 SD-score/week, 95% CI 0.052; 0.119, P < 0.001); and head (β = 0.055 SD-score/week, 95% CI 0.019; 0.091, P = 0.003). We also observed positive associations between n-3:n-6 PUFA ratio and birth weight (β = 0.76 SD-score, 95% CI 0.22; 1.29, P = 0.006), and duration of pregnancy (β = 1.32 weeks, 95% CI 0.24; 2.40, P = 0.02). CONCLUSIONS These results are consistent with the hypothesis that a higher n-3:n-6 PUFA ratio is important for fetal health.