Abstract
A distinctive pattern of recurrent rapid falls in fetal heart rate, called decelerations, are commonly associated with uterine contractions during labour. These brief decelerations are mediated by vagal activation. The reflex triggering this vagal response has been variably attributed to a mechanoreceptor response to fetal head compression, to baroreflex activation following increased blood pressure during umbilical cord compression, and/or a Bezold–Jarisch reflex response to reduced venous return from the placenta. Although these complex explanations are still widespread today, there is no consistent evidence that they are common during labour. Instead, the only mechanism that has been systematically investigated, proven to be reliably active during labour and, crucially, capable of producing rapid decelerations is the peripheral chemoreflex. The peripheral chemoreflex is triggered by transient periods of asphyxia that are a normal phenomenon associated with all uterine contractions. This should not cause concern as the healthy fetus has a remarkable ability to adapt to these repeated but short periods of asphyxia. This means that the healthy fetus is typically not at risk of hypotension and injury during uncomplicated labour even during repeated brief decelerations. The physiologically incorrect theories surrounding decelerations that ignore the natural occurrence of repeated asphyxia probably gained widespread support to help explain why many babies are born healthy despite repeated decelerations during labour. We propose that a unified and physiological understanding of intrapartum decelerations that accepts the true nature of labour is critical to improve interpretation of intrapartum fetal heart rate patterns. (Figure presented.).
| Original language | English |
|---|---|
| Pages (from-to) | 4711-4725 |
| Number of pages | 15 |
| Journal | Journal of Physiology |
| Volume | 594 |
| Issue number | 17 |
| DOIs | |
| Publication status | Published - 1 Sep 2016 |
| Externally published | Yes |
Cite this
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The myths and physiology surrounding intrapartum decelerations : the critical role of the peripheral chemoreflex. / Lear, Christopher A.; Galinsky, Robert; Wassink, Guido; Yamaguchi, Kyohei; Davidson, Joanne O.; Westgate, Jenny A.; Bennet, Laura; Gunn, Alistair J.
In: Journal of Physiology, Vol. 594, No. 17, 01.09.2016, p. 4711-4725.Research output: Contribution to journal › Review Article › Research › peer-review
TY - JOUR
T1 - The myths and physiology surrounding intrapartum decelerations
T2 - the critical role of the peripheral chemoreflex
AU - Lear, Christopher A.
AU - Galinsky, Robert
AU - Wassink, Guido
AU - Yamaguchi, Kyohei
AU - Davidson, Joanne O.
AU - Westgate, Jenny A.
AU - Bennet, Laura
AU - Gunn, Alistair J.
PY - 2016/9/1
Y1 - 2016/9/1
N2 - A distinctive pattern of recurrent rapid falls in fetal heart rate, called decelerations, are commonly associated with uterine contractions during labour. These brief decelerations are mediated by vagal activation. The reflex triggering this vagal response has been variably attributed to a mechanoreceptor response to fetal head compression, to baroreflex activation following increased blood pressure during umbilical cord compression, and/or a Bezold–Jarisch reflex response to reduced venous return from the placenta. Although these complex explanations are still widespread today, there is no consistent evidence that they are common during labour. Instead, the only mechanism that has been systematically investigated, proven to be reliably active during labour and, crucially, capable of producing rapid decelerations is the peripheral chemoreflex. The peripheral chemoreflex is triggered by transient periods of asphyxia that are a normal phenomenon associated with all uterine contractions. This should not cause concern as the healthy fetus has a remarkable ability to adapt to these repeated but short periods of asphyxia. This means that the healthy fetus is typically not at risk of hypotension and injury during uncomplicated labour even during repeated brief decelerations. The physiologically incorrect theories surrounding decelerations that ignore the natural occurrence of repeated asphyxia probably gained widespread support to help explain why many babies are born healthy despite repeated decelerations during labour. We propose that a unified and physiological understanding of intrapartum decelerations that accepts the true nature of labour is critical to improve interpretation of intrapartum fetal heart rate patterns. (Figure presented.).
AB - A distinctive pattern of recurrent rapid falls in fetal heart rate, called decelerations, are commonly associated with uterine contractions during labour. These brief decelerations are mediated by vagal activation. The reflex triggering this vagal response has been variably attributed to a mechanoreceptor response to fetal head compression, to baroreflex activation following increased blood pressure during umbilical cord compression, and/or a Bezold–Jarisch reflex response to reduced venous return from the placenta. Although these complex explanations are still widespread today, there is no consistent evidence that they are common during labour. Instead, the only mechanism that has been systematically investigated, proven to be reliably active during labour and, crucially, capable of producing rapid decelerations is the peripheral chemoreflex. The peripheral chemoreflex is triggered by transient periods of asphyxia that are a normal phenomenon associated with all uterine contractions. This should not cause concern as the healthy fetus has a remarkable ability to adapt to these repeated but short periods of asphyxia. This means that the healthy fetus is typically not at risk of hypotension and injury during uncomplicated labour even during repeated brief decelerations. The physiologically incorrect theories surrounding decelerations that ignore the natural occurrence of repeated asphyxia probably gained widespread support to help explain why many babies are born healthy despite repeated decelerations during labour. We propose that a unified and physiological understanding of intrapartum decelerations that accepts the true nature of labour is critical to improve interpretation of intrapartum fetal heart rate patterns. (Figure presented.).
UR - http://www.scopus.com/inward/record.url?scp=84986253481&partnerID=8YFLogxK
U2 - 10.1113/JP271205
DO - 10.1113/JP271205
M3 - Review Article
VL - 594
SP - 4711
EP - 4725
JO - The Journal of Physiology
JF - The Journal of Physiology
SN - 0022-3751
IS - 17
ER -