The Vagal Factor in Foetal Heart Rate Change I.—The Effect of Abdominal Pressure

Bradfield, Alan

doi:10.1111/j.1479-828x.1961.tb00089.x

Cited by 14 publications

(4 citation statements)

References 7 publications

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“…In parallel, thumb sucking is rarely observed before 15 weeks PC but becomes more frequent afterwards (Hepper, Shahidullah, & White, 1991). A pressure on the maternal abdomen can also be perceived by the fetus (from 32 to 40 weeks PC) who reacts with co-occurring heart rate changes (Bradfield, 1961;Issel, 1983;Walker, Grimwade, & Wood, 1973).…”

Section: Current Knowledge Of Newborns' Umwelt Tactile Perceptionmentioning

confidence: 99%

The human newborn’s umwelt: Unexplored pathways and perspectives

et al. 2017

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Historically, newborns, and especially premature newborns, were thought to "feel nothing." However, over the past decades, a growing body of evidence has shown that newborns are aware of their environment, but the extent and the onset of some sensory capacities remain largely unknown. The goal of this review is to update our current knowledge concerning newborns' perceptual world and how ready they are to cope with an entirely different sensory environment following birth. We aim to establish not only how and when each sensory ability arises during the pre-/postbirth period but also discuss how senses are studied. We conclude that although many studies converge to show that newborns are clearly sentient beings, much is still unknown. Further, we identify a series of internal and external factors that could explain discrepancies between studies, and we propose perspectives for future studies. Finally, through examples from animal studies, we illustrate the importance of this detailed knowledge to pursue the enhancement of newborns' daily living conditions. Indeed, this is a prerequisite for assessing the effects of the physical environment and routine procedures on newborns' welfare.

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Section: Current Knowledge Of Newborns' Umwelt Tactile Perceptionmentioning

confidence: 99%

The human newborn’s umwelt: Unexplored pathways and perspectives

et al. 2017

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“…Passive tactile stimuli (e.g. pressures on the maternal abdomen) can already be perceived by the fetus [11], [12], while premature and full-term newborns are known to perceive and react not only to nociceptive stimuli (e.g. heel lance; e.g.…”

Section: Introductionmentioning

confidence: 99%

Higher tactile sensitivity in preterm infants at term-equivalent age: A pilot study

André¹,

Durier²,

Beuchée

et al. 2020

PLoS ONE

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Despite a growing body of research on perinatal sensory abilities, data on the extent of tactile sensitivity and more particularly passive touch (i.e. sensitivity to a stimulation imposed on the skin) are relatively limited, and the development and processing of tactile function are still thus little known. This question is particularly of high importance for infants with atypical early development such as those born prematurely who are exposed to many sensory (including tactile) stimulations (being in a hospital setting) during a critical period of brain development and those born at early term whose birth occurs at the precise time of cortical reorganization, in particular in the sensory areas. Some parents and health-care providers have for instance reported that children born prematurely exhibit atypical (e.g. higher) sensitivity to "benign" tactile stimuli. In the present study, we hypothesized that preterm and earlyterm infants may show altered tactile sensitivity. We compared the behavioral responses around term-equivalent age of infants born either pre-term, early-term or at term to the application of a light (0.008 grams) mechanical stimulus. We found that almost all preterm infants perceive this tactile stimulus, contrarily to the two other groups of infants. This extreme tactile sensitivity may be due to experiential, maturational or more likely both processes. We also compared the tactile sensitivity of these infants to that of adults. We found that adults were irresponsive to the light mechanical stimulus. This finding opens not only new insights in understanding development of tactile processing, but also new lines of thought about the particular sensory world of premature and early-term infants and hence about the potential impact of early care practices.

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“…Previous exploratory experiments in fetal goats, fetal sheep and neonatal/postnatal rabbits all show that vagotomy delays the onset of bradycardia during severe hypoxaemia (Barcroft, 1946; Westgate et al., 2007). Reports in human fetuses also show that anti‐cholinergics abolish some, but not all, intrapartum decelerations (Bradfield, 1961, 1962; Hon et al., 1961; Méndez‐Bauer et al., 1963). These studies imply that myocardial hypoxia has a role in some intrapartum decelerations.…”

Section: Discussionmentioning

confidence: 98%

Dissecting the contributions of the peripheral chemoreflex and myocardial hypoxia to fetal heart rate decelerations in near‐term fetal sheep

Lear

Beacom

Dhillon

et al. 2023

The Journal of Physiology

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Brief repeated fetal hypoxaemia during labour can trigger intrapartum decelerations of the fetal heart rate (FHR) via the peripheral chemoreflex or the direct effects of myocardial hypoxia, but the relative contribution of these two mechanisms and how this balance changes with evolving fetal compromise remain unknown. In the present study, chronically instrumented near‐term fetal sheep received surgical vagotomy (n = 8) or sham vagotomy (control, n = 11) to disable the peripheral chemoreflex and unmask myocardial hypoxia. One‐minute complete umbilical cord occlusions (UCOs) were performed every 2.5 min for 4 h or until arterial pressure fell below 20 mmHg. Hypotension and severe acidaemia developed progressively after 65.7 ± 7.2 UCOs in control fetuses and 49.5 ± 7.8 UCOs after vagotomy. Vagotomy was associated with faster development of metabolic acidaemia and faster impairment of arterial pressure during UCOs without impairing centralization of blood flow or neurophysiological adaptation to UCOs. During the first half of the UCO series, before severe hypotension developed, vagotomy was associated with a marked increase in FHR during UCOs. After the onset of evolving severe hypotension, FHR fell faster in control fetuses during the first 20 s of UCOs, but FHR during the final 40 s of UCOs became progressively more similar between groups, with no difference in the nadir of decelerations. In conclusion, FHR decelerations were initiated and sustained by the peripheral chemoreflex at a time when fetuses were able to maintain arterial pressure. After the onset of evolving hypotension and acidaemia, the peripheral chemoreflex continued to initiate decelerations, but myocardial hypoxia became progressively more important in sustaining and deepening decelerations. Key points Brief repeated hypoxaemia during labour can trigger fetal heart rate decelerations by either the peripheral chemoreflex or myocardial hypoxia, but how this balance changes with fetal compromise is unknown. Reflex control of fetal heart rate was disabled by vagotomy to unmask the effects of myocardial hypoxia in chronically instrumented fetal sheep. Fetuses were then subjected to repeated brief hypoxaemia consistent with the rates of uterine contractions during labour. We show that the peripheral chemoreflex controls brief decelerations in their entirety at a time when fetuses were able to maintain normal or increased arterial pressure. The peripheral chemoreflex still initiated decelerations even after the onset of evolving hypotension and acidaemia, but myocardial hypoxia made an increasing contribution to sustain and deepen decelerations.

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The Vagal Factor in Foetal Heart Rate Change I.—The Effect of Abdominal Pressure

Cited by 14 publications

References 7 publications

The human newborn’s umwelt: Unexplored pathways and perspectives

The human newborn’s umwelt: Unexplored pathways and perspectives

Higher tactile sensitivity in preterm infants at term-equivalent age: A pilot study

Dissecting the contributions of the peripheral chemoreflex and myocardial hypoxia to fetal heart rate decelerations in near‐term fetal sheep

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