While many studies have focused on DHA and its role in fetal and neonatal development, few studies have addressed the role of the omega-6 LCPUFA AA during fetal life and after preterm birth. Like DHA, AA is an important component of cell membranes. Altered cell membrane composition results in altered cell function. AA is abundant in the vascular endothelium and in glia where it plays different roles than DHA which is especially abundant in retinal rod outer segments and in synapses and brain grey matter. In the retina AA metabolites contribute to neurovascular coupling i.e. modulation of blood flow with neuronal activity. Metabolites of AA both stimulate and inhibit inflammation and angiogenesis. In addition, AA is involved in blood vessel tonus control with AA derivatives mediating both vessel relaxation and contraction. Low AA concentrations are associated with late onset sepsis in preterm infants. Improved development of very preterm infants fed twice as much AA as DHA than of infants fed equal amounts of AA and DHA was recently reported.