OBJECTIVE Increased circulating nucleated erythrocytes (NRBCs) in the newborn period can be markers of chronic fetal hypoxia, which in turn may be a risk factor for intracranial hemorrhage (IVH). To evaluate the relation between chronic intrauterine hypoxia and IVH, we compared the courses of the absolute NRBC (ANRBC) count in preterm newborns with and without intracranial hemorrhage. METHODS We measured ANRBC counts in the first 6 days of life in appropriate for gestational age newborns at 32 weeks' gestation or earlier with (n = 46) and without (n = 103) IVH, who were not at risk for altered erythropoiesis. RESULTS The ANRBC counts at birth were higher in infants who developed severe IVH than in control infants without IVH (P < .03). The ANRBC counts peaked on day 2 or 3 in newborns with IVH, but declined continuously from a peak on day 1 in the control group. Stepwise regression analysis of multiple variables revealed that the grade of IVH had the greatest impact on ANRBC counts. An ANRBC count of at least 2.0 x 10(9)/L on day 1 of life had a sensitivity of 63% and a specificity of 79% in predicting grade III or IV IVH: CONCLUSIONS An elevated or increasing ANRBC count in a preterm newborn is a potential marker for an impending or present severe IVH, respectively, and may reflect a state of altered prenatal or postnatal erythropoiesis.