Recommendations exist for increased intake of ω-3 fatty acids, particularly docosohexanoic acid (DHA) in pregnancy with the nutritional supplement industry successfully marketing prenatal supplements with DHA to optimize brain function of mother and infant. However, the mechanisms contributing to these effects remain poorly characterised. Maternal supplementation with ω-3 fatty acids may modulate inflammatory processes resulting in decreased levels of maternal and fetal inflammatory cytokines.  For the fetus, accretion is greatest during the last trimester of pregnancy. Therefore, infants receive relatively low levels of DHA supplied by parenteral nutrition, human milk or supplemented infant formulas following preterm delivery and yet may have an increased requirement for DHA compared with their term counterparts. As a result, an inadequate supply in the neonatal period is hypothesized to contribute to poor developmental outcome. Potentially long-term consequences of this initial perturbation in essential fatty acid profile include effects on growth, inflammation and immune function. Some epidemiological investigations of maternal and infant nutritional supplementation with ω-3 fatty acids propose a role for DHA and eicosapentanioc acid (EPA) in reducing preterm delivery and the incidence of major neonatal morbidities associated with being born prematurely. However, questions remain about their clinical use including the relative biological actions of individual ω-3 fatty acids. Further, concerns regarding the susceptibility of ω-3 fatty acids to oxidative degradation remain. With the placenta a major source of reactive oxygen species production causally implicated in processes adversely affecting the fetus and newborn, the effects of ω-3 fatty acids on placental and neonatal pro-oxidant-antioxidant balance and response to inflammation will be discussed.