Omega-3 cord plasma proportions and cognitive function trajectories from 5 to 15 years of age: a population-based cohort study.

Maternal diet during pregnancy, particularly omega-3 fatty acids, is critical for neurodevelopment, yet long-term associations with cognitive trajectories remain unclear. We evaluated prenatal omega-3 exposure in relation to longitudinal trajectories of inattentiveness, working memory, and fluid intelligence from childhood through adolescence within the Spanish Environment and Childhood project. Cord plasma proportions of alfa‑linolenic acid (ALA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) were measured in 953 participants. Linear mixed-effects models evaluated overall average main effects and age-interaction cognitive trajectories across follow-up (5-15 years). In main effect models, higher ALA and DHA proportions were associated with lower overall inattentiveness (β = - 0.19, 95% CI: - 0.35, - 0.02; and β = - 0.20, 95% CI: - 0.35, - 0.04, respectively), and higher DHA was associated with better overall working memory (β = 0.24, 95% CI: 0.08, 0.39). Longitudinal interaction models with age revealed domain-specific trajectories. Higher cord plasma ALA was associated with early advantages in attention and fluid intelligence, but exhibited significant attenuation over time (β = 0.10, 95%CI = 0.06; 0.14; and β = - 0.11, 95%CI = - 0.15; - 0.07). Conversely, higher DHA predicted steeper trajectory improvements over time for inattentiveness (β = - 0.06, 95%CI = - 0.10; - 0.02) and fluid intelligence (β = 0.08, 95%CI = 0.04; 0.12), alongside marked early childhood advantages in working memory that attenuated over time (β = - 0.05, 95%CI = - 0.09; - 0.01). Prenatal omega‑3 s may show distinct domain-specific and age-dependent associations with cognitive trajectories. Cord plasma ALA may support early attention and fluid intelligence, whereas DHA may contribute to sustained long-term cognitive maturation alongside early working memory performance.