Maternal n-3 Polyunsaturated Fatty Acid During Pregnancy and Lactation: Linking Brain Lipid Biology to Cognitive Outcomes

Adequate maternal nutrition during pregnancy and lactation is essential for fetal and infant brain development. Among dietary lipids, n-3 polyunsaturated fatty acids (n-3 PUFAs), particularly docosahexaenoic acid (C22:6n-3, DHA), are of major biological relevance because this FA is preferentially transferred from the mother, accumulates rapidly in the developing brain, and contributes to membrane organization, neuronal differentiation, synaptic maturation, and lipid-mediated signaling. This review integrates current evidence on maternal n-3 PUFA metabolism during pregnancy and lactation, placental and blood–brain barrier transport of DHA, and the mechanisms linking cerebral n-3 PUFA availability to neurodevelopment and cognitive function. Attention is given to selective DHA transport, brain lipid remodeling, synaptic plasticity, neuroimmune regulation, and the translation of experimental findings into human developmental outcomes. Across experimental and human studies, the clearest functional signal emerges under developmental n-3 PUFA deficiency or defined biological challenge, whereas supplementation above nutritional adequacy produces smaller and less consistent cognitive effects. These findings support a context-dependent model in which the functional consequences of n-3 PUFA availability are shaped by baseline nutritional status, developmental timing, brain region, biological challenge, and the assessed cognitive domain. Accordingly, DHA is best understood as an essential component of normal brain development rather than as a nutrient whose supplementation necessarily enhances cognition above nutritional adequacy.