['Pathogenesis of intraventricular hemorrhage (IVH) in premature infants is multifactorial. Little is known about the influence of pro-inflammatory cytokine activation on the coagulation system in extremely preterm infants and its impact on the development of IVH.', 'To determine the interaction between serum interleukin-6 (IL-6) and the coagulation system in preterm infants predisposed to the development of IVH.', 'Vitamin K-dependent coagulation factors were examined retrospectively in 132 extremely preterm infants prior to vitamin K administration at the first day of life. Patients were grouped according to the occurrence of IVH and serum concentration of IL-6 >/<100 pg/ml.', 'Occurrence of IVH was associated with clinical diagnosis of chorioamnionitis, low gestational age, high CRIB score, air leak, catecholamine treatment, low initial hematocrit and increased serum concentration of IL-6. Infants developing IVH showed a diminished coagulation profile. Multivariable logistic regression analysis revealed decreased activity of coagulation factor VII, development of pneumothorax and low hematocrit as independent risk factors for the development of IVH. An increased IL-6 serum concentration was associated with a significantly decreased activity of coagulation factor VII and increased levels of fibrinogen.'] Are elevated interleukin-6 concentration and alterations of the coagulation system associated with the development of intraventricular hemorrhage in extremely preterm infants?