A recent study in humans and in animals shows the role of the complex formed by plasminogen activator (t-PA) and its inhibitor (PAI-1) in the induction of vascular fragility via stromelysin (MMP-3). FIBRINAT study in Rouen University Hospital showed a rate of complex t-PA-PAI1 probably very high in preterm infants. An other factor maturation PDGF-C induced by t-PA is associated with the vascular embrittlement. Among the few genetic factors associated with cerebral palsy include 2 SNP of PAI-1 gene and one SNP in the gene of endothelial NO synthase.