Our observation of decreased levels of coagulant Factor II (F2) and Factor IX (F9) together with decreased levels of fibrinolysis mediators FGB, FGG, FBLN1 and PLG concur with anticoagulant hypofunction previously described in infants with respiratory distress syndrome (RDS)32,33 where under pathologic conditions, such as following initiation of mechanical ventilation, the hemostatic balance favours thrombosis34,35 and fibrin deposition36,37. This evidence concerns the gene F9 and newborn respiratory distress syndrome.