The ductus arteriosus (DA) normally closes after birth as a result of exposure to oxygen. Its persistence of DA (PDA) occurs in 20 to 50% of very preterm infants and is associated with significant morbidity and mortality: prolongation of respiratory assistance, pulmonary haemorrhage, -necrotizing enterocolitis (NECU), intraventricular haemorrhage and death. PDA management is one of the most discussed aspects in neonatology. The treatment is either conservative (controlled fluid intake, monitoring of cerebral flows, diuretics), or pharmacological (ibuprofen or paracetamol per os), or surgical (thoracotomy + ligature or catheterization + plug). The success rate of pharmacological treatment of CAP is 30% in the most immature children. When medical treatment fails, surgical or endovascular treatment is considered. However, these are associated with complications such as recurrent nerve lesion, thoracotomy, failure to close DA, migration of the plug. Therefore individualized assessment balances the expected benefits of CAP treatment against the risks associated with the treatments for each patient. The main complication of CAP is the impossibility of weaning the patient from ventilatory assistance. On the one hand because of PDA, but also very often because of the concomitant development of bronchopulmonary dysplasia (BPD) due to pulmonary lesions secondary to assisted ventilation and especially to inflammation. At 3 weeks of life, if attempts at ventilatory weaning have failed, postnatal corticosteroid therapy is considered in the 4th week of life in accordance with current recommendations. The most commonly used postnatal corticosteroids are dexamethasone (DXM), hydrocortisone hemisuccinate (HSHC) and betamethasone (BTM). DXM (intravenous) is effective and is the most widely used product worldwide, but its use is associated with impaired postnatal growth and suboptimal neurodevelopment. HSHC (intravenous) is an alternative to DXM and has shown some effectiveness, without the adverse effects of DXM. The BTM is also an alternative, but has been used less than the other products because it is not widely available in some countries. Its advantage is that it can be given orally, but there is little published data on the effect of BTM. In this context, it has been used in some neonatal units and have shown some effectiveness. In the Neonatology department of the Croix Rousse hospital, oral BTM has been used since 2005 and has been evaluated favorably, since it allows the child to be weaned from ventilatory assistance. When using BTM, we observed not only a positive respiratory effect, but also DA closure, reducing the need for ligation of the ductus arteriosus by surgery or catheterization