2.2 potential prognostic variables The most important known risk factor for bleeding is low gestational age.(1) In the specific case of IVH, it is thought that the prematurity of the brain - which has a highly vascularized germinal matrix that can easily be damaged - is an important causal factor. However, several other factors have been associated with an increased risk of bleeding, for example low Apgar scores, acidosis, vaginal birth, need for mechanical ventilation, disordered coagulation,NEC, DIC, indomethacin or surfactant treatment, low oxygen saturation levels, a low Score for Neonatal Acute Physiology (SNAP), and many more. But many of these studies have severe limitations such as lack of multivariate analysis, unclear selection of controls, small numbers and different study populations. Most are also limited to a baseline risk assessment, without a possibility to correct the risk assessment as the clinical status of the child changes. Therefore there is no clarity as to which factors are really relevant in clinical practice when assessing neonatal bleeding in neonates with thrombocytopenia.