Objective: The purpose of this study was to measure by near-infrared spectroscopy changes in human fetal cerebral oxyhemoglobin, deoxyhemoglobin, and cerebral blood volume during labor and to calculate mean cerebral hemoglobin oxygen saturation.
Study design: The effects of uterine contractions with and without fetal heart rate decelerations were compared in eight singleton term fetuses. Results were analyzed by analysis of variance.
Results: In six of eight fetuses normal uterine contractions were associated with proportional decreases in both oxyhemoglobin and deoxyhemoglobin and a fall in cerebral blood volume without desaturation of cerebral hemoglobin. Contractions with fetal heart rate decelerations produced different results in that oxyhemoglobin fell but deoxyhemoglobin rose, indicating cerebral desaturation. In two of the eight fetuses normal contractions were associated with increases in oxyhemoglobin, deoxyhemoglobin, and cerebral blood volume; no decelerations were seen in either fetus. Mean cerebral hemoglobin oxygen saturation calculated during normal contractions was 43% +/- 10% (SD).
Conclusion: Uterine contractions were associated with detectable changes from baseline in cerebral oxyhemoglobin, deoxyhemoglobin, and cerebral blood volume.