Levels of many coagulation factors are low in the healthy infant and even lower in the asphyxiated premature infant. We investigated whether a brief exposure to asphyxia at the time of birth causes the activation and consumption of coagulation factors. Following delivery by caesarean section, premature lambs were asphyxiated by occluding the endotracheal tube for 10 min and then resuscitated. Blood was obtained prior to and following birth for measurement of blood gases and the coagulation system. Birth asphyxia in the premature lamb resulted in thrombin generation and rapid consumption of specific coagulation factors.