Repeated umbilical cord compression and periventiricular leubomalacia

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We characterized the detailed hemodynamics of fetal blood pressure, heart rate, umbilical blood flow and carotid blood flow responses to partial compression of the umbilical cord and tested the hypothesis that repeated partial umbilical cord compression is a predisposing factor to genesis of periventricular leukomalacia. In chronically instrumented fetal sheep at 120-130 days of gestation, partial compression of the umbilical cord was induced 15 times, each for 2 min at 2 min intervals. Each cord copression reduced umbilical blood flow by 50%.In an early stage of the compression experiment, carotid arterial blood flow increased and carotic arterial resistance decreased, however, the resistance was gradually raised by repetition of compression and finally higher than the basal level. This result demonstrates that fetal brain circulation may be modified by preexposure to repeated intrauterine challenges.