Review: Fetal defenses against intrapartum head compression
Review: Fetal defenses against intrapartum head compression – implications for intrapartum decelerations and hypoxic-ischemic injury by Christopher LEAR, et al.
Chicago, IL
September 12, 2022
Intrapartum uterine contractions and engagement of the fetus in the birth canal can compress the fetal head. There is a long-standing view that this head compression is benign in most cases and is a common cause of intrapartum fetal heart rate decelerations.
In this review article the authors address the following:
The physiological adaptations of the fetus to increased intracranial pressure (ICP) during labor,
The relevance of increased ICP to fetal adaptations of labor,
Potential importance as a mediator of intrapartum decelerations,
Implications for hypoxic-ischemic (HI) brain injury.
Numerous animal and human studies were reviewed, and the authors came to the following conclusions:
The review suggests that head compression has been mistakenly over-emphasized as a common mediator of intrapartum decelerations in the late first stage and the second stage of labor.
This has distracted birth attendants from focusing on the key factors of the depth, duration, and frequency of decelerations and the accumulating oxygen debt.
Although fetal head compression is not intrinsically benign, the fetus has robust adaptations to mitigate increased intracranial pressure, which are augmented by its unique anatomic defenses of the fontanel and nonfused skull bones that allow molding of the head shape.
Based on all the available evidence, the authors conclude that isolated periods of head compression such as those that may occur during a normal, spontaneous delivery, are highly unlikely to lead to significant injury unless the fetus is already severely compromised by preceding severe hypoxemia.
To read the full review article, please click here (note opens link on the American Journal of Obstetrics & Gynecology’s website).