Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
 
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal
Le bâillement, du réflexe à la pathologie
Le bâillement : de l'éthologie à la médecine clinique
Le bâillement : phylogenèse, éthologie, nosogénie
 Le bâillement : un comportement universel
La parakinésie brachiale oscitante
Yawning: its cycle, its role
Warum gähnen wir ?
 
Fetal yawning assessed by 3D and 4D sonography
Le bâillement foetal
http://www.baillement.com

mystery of yawning 

mise à jour du
7 juin 2017
J Matern Fetal Neonatal Med. 2017
4D ultrasound study of fetal facial expressions in the third trimester of pregnancy
 
AboEllail MAM, Kanenishi K, Mori N, Mohamed OAK, Hata T

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Tous les articles consacrés au bâillement foetal
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Sonography Edited by: Kerry Thoirs
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Chapter 18 Pages 325-332
 
Piontelli A. Fetal Yawning in Development of Normal Fetal Movements. The first 25 weeks of gestation. Spinger. 2010. 135p.
 
 Abstract
 
To evaluate the frequencies of fetal facial expressions in the third trimester of pregnancy, when fetal brain maturation and development are progressing in normal healthy fetuses.
 
Four-dimensional (4_D) ultrasound was used to examine the facial expressions of 111 healthy fetuses between 30 and 40_weeks of gestation. The frequencies of seven facial expressions (mouthing, yawning, smiling, tongue expulsion, scowling, sucking, and blinking) during 15-minute recordings were assessed. The fetuses were further divided into three gestational age groups (25 fetuses at 30-31_weeks, 43 at 32-35_weeks, and 43 at 36_weeks). Comparison of facial expressions among the three gestational age groups was performed to determine their changes with advancing gestation.
 
Mouthing was the most frequent facial expression at 30-40_weeks of gestation, followed by blinking. Both facial expressions were significantly more frequent than the other expressions (p_<_.05). The frequency of yawning decreased with the gestational age after 30_weeks of gestation (p_=_.031). Other facial expressions did not change between 30 and 40_weeks. The frequency of yawning at 30-31_weeks was significantly higher than that at 36-40_weeks (p_<_.05). There were no significant differences in the other facial expressions among the three gestational age groups.
 
Our results suggest that 4D ultrasound assessment of fetal facial expressions may be a useful modality for evaluating fetal brain maturation and development. The decreasing frequency of fetal yawning after 30_weeks of gestation may explain the emergence of distinct states of arousal.
 
Introduction
 
Fetal brain development starts as early as in the 7th week of gestation [1]. A series of brain developmental changes takes place throughout pregnancy [2]. In the first and second trimesters, anatomical changes are the hallmark [3,4], and therefore can be directly assessed by two-dimensional (2 D) sonography [5].
 
On the other hand, functional brain developmental changes predominate over anatomical changes in the third trimester of pregnancy [6]. Functional connections between the cerebral cortex and peripheral nervous system appear at 28 weeks of gestation, as indicated by evoked potentials [7]. The upper motor control system (cerebral hemispheres and basal ganglia) becomes mature at 34 weeks of pregnancy [8]. Development of the six-layered lamination of the neocortex takes place after 32 weeks, as a result of neural differentiation and the laminar distribution of thalamocortical axons [9]. The third trimester is also characterized by brain stem maturation with a distinguished sleep&endash;wakefulness pattern due to pontine maturation [10].
 
Facial expressions are not separate from central nervous system (CNS) developmental changes. They start to be observed at 10&endash;11 weeks of gestation [3]. Changes in their frequencies occur through gestation [11]. Eye movement patterns become more complex in the third trimester, due to mid-brain maturation. At 36&endash;38 weeks, eye movements become linked with the fetal heart rate [12,13].
 
These changes in the frequencies of facial expression, and their link with other body functions represent a crucial part of a set of behavioral states [14]. Previous neurodevelopmental study concluded that these behavioral states develop due to the functional development of the fetal CNS [15]. Moreover, it is well documented that fetal behavior represented by fetal movements and facial expressions reflect well-being of the fetal brain and CNS [16&endash;19]. Therefore, the evaluation of facial expressions, especially in the third trimester of pregnancy, might represent a direct method to assess developmental changes of the fetal brain and CNS. The change in frequencies of these expressions at that stage might reflect maturity of brain areas controlling these facial expressions.
 
There have been numerous studies on fourdimensional (4D) ultrasound assessment of fetal facial expressions [20&endash;29]. However, the number of subjects studied in the third trimester of pregnancy, especially after 36 weeks of gestation, was very small. Because of the small amounts of amniotic fluid relative to the fetal size, and the difficulty in obtaining an ideal sagittal view of the fetal face depending on the fetal position, there are limitations regarding 4D ultrasound studies of fetal facial expressions.
 
This study focuses on 4D ultrasound evaluation of fetal facial expressions in the third trimester as an indicator of brain development at this critical stage, which is believed to represent maturational stage of the fetal brain and CNS functions [30].
 
Yawning was the only facial expression to demonstrate a significant decrease in frequency with advancing gestation (p<.05) (Figure 2), although the correlation coefficient for yawning and increasing gestational age was low (r_.184). The other six facial expressions did not show a significant change in frequency with gestational age.
 
 
Discussion
 
In our previous studies on 4D ultrasound evaluations of fetal facial expressions at 20&endash;34 weeks of gestation, mouthing was the sole most frequent facial expression [26,33,34]. Kurjak et al. [23] reported that blinking and mouthing movements are dominant between 30 and 33 weeks of gestation. However, there has been no 4D ultrasound study on the patterns of the frequency of fetal facial expressions late in the third trimester. In this study, mouthing and blinking were the most frequent facial expressions at 30&endash;31, 32&endash;35, 36&endash;40, and 30&endash;40 weeks of gestation, respectively. After 30 weeks of gestation, there is an increase in long-duration fetal movements, referred to as epochs and episodes, and the neurobehavioral regulation of fetal movements is crucial during this period [35]. Horimoto et al. [30] found that the concurrence of regular mouthing with the non-rapid eye movement period after 35 to 36 weeks' gestation suggests the maturation of fetal brain functioning seen in the newborn. Brain functions also regulate the rate of spontaneous eye blinking [36,37], and an increase in the spontaneous eye blinking rate is thought to be related to central dopamine system maturation [38&endash;41]. These results suggest that the concurrence of mouthing movement and eye blinking may be related to the maturation of fetal brain development after 30 weeks of gestation.
 
It was reported that there is no change in the frequency of fetal yawning assessed by 2D sonography between 20 and 36 weeks of gestation [42]. In this study using 4D ultrasound, yawning showed a decreased frequency with advancing gestation in the third trimester of pregnancy, coinciding with the results obtained with 4D ultrasound by Reissland et al. [43], as well as Kurjak et al. [23]. Yawning is concerned with the arousal process of the brain [44]. With advancing gestation, the rhythmic control of sleep and wake times becomes more established. This results in frequent waking episodes and less of a need for yawning as a stimulus for brain arousal. "Yawning indicates a harmonious progress in the development of both the brainstem and the peripheral neuromuscular function, testifying to the induction of an ultradian rhythm of vigilance" [45]. Giganti et al. [44] also demonstrated a decreased frequency of yawning in preterm and near-term infants with the advancement of age. Therefore, the period of 30 weeks of gestation might represent the emergence of distinct states of fetal brain arousal, as indicated by the significant decrease in the frequency of yawning. However, the low correlation coefficient for yawning and increasing gestational age as well as the overlapping ranges of numbers of yawning episodes among the three gestational age groups might indicate that the emergence of distinct states of fetal brain arousal after 30 weeks is very slowly progressing.
 
Reissland et al. [46] speculated that the increased frequency of fetal scowling with advancing gestation might be an adaptive process, which is beneficial after birth. Fetal scowling may represent the fetal response to pain [46,47]. In this study, its frequency did not change after 30 weeks of gestation. The somatosensory evoked potentials (translating pain processing in the somatosensory cortex) develop at 29 weeks [48], and this might indicate the constant frequency of scowling in the third trimester of pregnancy.
 
Sato et al. [33] showed that the frequency of fetal smiling increased with advancing gestation between 20 and 34 weeks of gestation. In this study, the frequency of smiling did not change after 30 weeks of gestation. Fetal smiling may facilitate the development of facial muscles in utero, and may enhance a positive parental attitude [49]. The development of smiling in utero may represent an adaptive process to postnatal life. In this study, the frequency of fetal suckling remained unchanged between 30 and 40 weeks of gestation. Previous 4D ultrasound studies reported its constant frequency between 20 and 34 weeks [33], and the results reported by Yigiter and Kavak [25], and Reissland et al. [50] also confirmed the stable frequency of fetal lip puckering in the second half of pregnancy [39]. Intrauterine sucking lacks the real postnatal stimulus (breast or bottle). However, its stable frequency with gestation indicates its importance as an essential training step in preparation for postnatal feeding.
 
The frequency of tongue expulsion was found to be constant between 30 and 40 weeks of gestation in this study. Kurjak et al. [23] also found that its frequency is constant after 28 weeks of gestation. This constant frequency may represent a maintenance state of tongue training as an essential preparatory step for its use in lactation, as well as speech functions in postnatal life. Limitations of this study may be the small sample size and the lack of two investigators assessing the movements independently and blindly to gestational age. Therefore, intra- and inter-observer reproducibility for 4D ultrasound assessment of fetal facial expressions should be investigated in further research. In this investigation, most of the examinations were performed in the morning with few cases in the afternoon. This cannot allow analysis of the difference in fetal activity based on time/timing of the examinations. Future studies involving a larger sample size are needed to investigate the reproducibility of 4D ultrasound assessment of fetal facial expressions and the difference in fetal activity at the time/timing of the examination.
 
In conclusion, this study provided the normal parameters of fetal facial expressions in the third trimester of pregnancy, and suggests the possible link between facial expressions and brain development at this stage, when the fetal brain reaches advanced stage of maturity. Therefore, the full realization of fetal facial expressions and fetal behavior in different stages of gestation might enable us to better understand the functional development of the fetal brain and CNS. The developmental changes of facial expressions can selectively indicate the maturation and development of different parts of the fetal brain and CNS.