Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand.
Fetal Physiology and Neuroscience Group, Department of Physiology, The University of Auckland, Auckland, New Zealand; Department of Obstetrics and Gynaecology, The University of Auckland, Auckland, New Zealand.
Am J Obstet Gynecol. 2023 May;228(5S):S1117-S1128. doi: 10.1016/j.ajog.2021.11.1352. Epub 2021 Nov 18.
Uterine contractions during labor and engagement of the fetus in the birth canal can compress the fetal head. Its impact on the fetus is unclear and still controversial. In this integrative physiological review, we highlight evidence that decelerations are uncommonly associated with fetal head compression. Next, the fetus has an impressive ability to adapt to increased intracranial pressure through activation of the intracranial baroreflex, such that fetal cerebral perfusion is well-maintained during labor, except in the setting of prolonged systemic hypoxemia leading to secondary cardiovascular compromise. Thus, when it occurs, fetal head compression is not necessarily benign but does not seem to be a common contributor to intrapartum decelerations. Finally, the intracranial baroreflex and the peripheral chemoreflex (the response to acute hypoxemia) have overlapping efferent effects. We propose the hypothesis that these reflexes may work synergistically to promote fetal adaptation to labor.
分娩时子宫收缩和胎儿在产道中的衔接会压迫胎儿头部。其对胎儿的影响尚不清楚，仍存在争议。在这个综合生理学综述中，我们强调了减速很少与胎儿头部受压有关的证据。接下来，胎儿通过激活颅内压力反射具有令人印象深刻的适应颅内压升高的能力，使得胎儿在分娩过程中大脑灌注保持良好，除非发生导致继发性心血管功能障碍的长时间全身低氧血症。因此，当头部受压发生时，并不一定是良性的，但似乎不是产时减速的常见原因。最后，颅内压力反射和外周化学感受器反射（对急性低氧血症的反应）具有重叠的传出效应。我们提出假设，这些反射可能协同作用，促进胎儿适应分娩。
