 Secondary hydroelectrolytic disorders with transient mineralocorticoid adrenal insufficiency is probably one of the factors responsible of these neurological deleterious outcomes as well as the occurrence of other complications bronchopulmonary dysplasia, enterocolitis necrotizing of extreme prematurity. Indeed, aside from the administration of antenatal steroids to induce maturation, the prevention of postnatal dehydration reduces the risk of intracranial hemorrhage in that population. However, high fluid intake are associated with an increased incidence of patent ductus arteriosus, of bronchopulmonary dysplasia and necrotizing enterocolitis. This necessitates the evaluation of preventive measures to avoid such fluid and electrolyte imbalances by a pharmacological approach based on mineralocorticoid administration in very premature infants, due to the relative aldosterone deficiency identified in this population. 