An embodied approach to fetal and newborn perceptual and sensorimotor development

The embodied approach argues that interaction with the environment plays a crucial role in brain development and that the presence of sensory effects generated by movements is fundamental. The movement of the fetus is initially random. Then, the repeated execution of the movement creates a link between it and its sensory effects, allowing the selection of movements that produce expected sensations. During fetal life, the brain develops from a transitory fetal circuit to the permanent cortical circuit, which completes development after birth. Accordingly, this process must concern the interaction of the fetus with the intrauterine environment and of the newborn with the new aerial environment, which provides a new sensory stimulation, light. The goal of the present review is to provide suggestions for neuroscientific research capable of shedding light on brain development process by describing from a functional point of view the relationship between the motor and sensory abilities of fetuses and newborns and the increasing complexity of their interaction with objects in the womb and outside of it.

Tail movements by late-term fetal pitvipers resemble caudal luring: prenatal development of an ambush predatory behaviour

With the advent of powerful imaging instruments, the prenatal behaviour of vertebrates has been discovered to be far more complex than previously believed, especially concerning humans, other mammals and birds. Surprisingly, the fetal behaviour of squamate reptiles (lizards, snakes and amphisbaenians), a group of over 11 000 extant species, are largely understudied. Using ultrasonography, 18 late-term pregnant copperhead snakes (Agkistrodon contortrix) from a single population were inspected for fecundity (number of fetuses). Unexpectedly, during the ultrasound procedure that involved 97 fetuses, we observed sinusoidal tail movements in 11 individuals from eight different copperhead mothers. These movements were indistinguishable from caudal luring, a mimetic ambush predatory strategy which is exhibited by newborn copperheads and other snakes. Caudal luring is initiated shortly after birth and is employed to attract susceptible vertebrate prey. Using the same ultrasound equipment and methods, we tested for this behaviour in two species of rattlesnakes (genus Crotalus) not known to caudal lure and none of the late-term fetuses showed any type of tail movements. Prenatal movements in humans and other vertebrates are known to be important for musculoskeletal and sensorimotor development. The fetal behaviours we describe for copperheads, and possibly other snakes, may be similarly important and influence early survival and subsequent fitness.

Music Modulates Autonomic Nervous System Activity in Human Fetuses

Context

Fetal Autonomic Nervous sysTem Evaluation (FANTE) is a non-invasive tool that evaluates the autonomic nervous system activity in a fetus. Autonomic nervous system maturation and development during prenatal life are pivotal for the survival and neuropsychiatric development of the baby.

Objective

Aim of the study is to evaluate the effect of music stimulation on fetal heart rate and specific parameters linked to ANS activity, in particular fetal heart rate variability.

Methods

Thirty-two women between the 32nd and 38th week with a singleton uncomplicated pregnancy were recruited. All FANTE data collections were acquired using a 10-derivation electrocardiograph placed on the maternal abdomen. In each session (5 min basal, 10 min with music stimulus, and 5 min post-stimulus), FANTE was registered. The music stimulus was “Clair de lune” Debussy, played through headphones on the mother’s abdomen (CTR: 31927).

Results

Music does not change the mean value of fetal heart rate. However, indices of total fetal heart rate variability statistically increase (RRsd p = 0.037, ANNsd p = 0.039, SD2 p = 0.019) during music stimulation in comparison to the basal phase. Heart rate variability increase depends mainly on the activation of parasympathetic branches (CVI p = 0.013), meanwhile, no significant changes from basal to stimulation phase were observed for indices of sympathetic activity. All the parameters of heart rate variability and parasympathetic activity remained activated in the post-stimulus phase compared to the stimulus phase. In the post-stimulus phase, sympathetic activity resulted in a significant reduction (LFn p = 0.037).

Conclusion

Music can influence the basal activity of the fetal autonomic nervous system, enhancing heart rate variability, without changing fetal heart rate mean value. Music is enabled to induce a relaxation state in a near-to-term fetus, mediated by parasympathetic activation and by a parallel sympathetic inhibition.

A Review on the Vagus Nerve and Autonomic Nervous System During Fetal Development: Searching for Critical Windows

The autonomic nervous system (ANS) is one of the main biological systems that regulates the body's physiology. Autonomic nervous system regulatory capacity begins before birth as the sympathetic and parasympathetic activity contributes significantly to the fetus' development. In particular, several studies have shown how vagus nerve is involved in many vital processes during fetal, perinatal, and postnatal life: from the regulation of inflammation through the anti-inflammatory cholinergic pathway, which may affect the functioning of each organ, to the production of hormones involved in bioenergetic metabolism. In addition, the vagus nerve has been recognized as the primary afferent pathway capable of transmitting information to the brain from every organ of the body. Therefore, this hypothesis paper aims to review the development of ANS during fetal and perinatal life, focusing particularly on the vagus nerve, to identify possible "critical windows" that could impact its maturation. These "critical windows" could help clinicians know when to monitor fetuses to effectively assess the developmental status of both ANS and specifically the vagus nerve. In addition, this paper will focus on which factors-i.e., fetal characteristics and behaviors, maternal lifestyle and pathologies, placental health and dysfunction, labor, incubator conditions, and drug exposure-may have an impact on the development of the vagus during the above-mentioned "critical window" and how. This analysis could help clinicians and stakeholders define precise guidelines for improving the management of fetuses and newborns, particularly to reduce the potential adverse environmental impacts on ANS development that may lead to persistent long-term consequences. Since the development of ANS and the vagus influence have been shown to be reflected in cardiac variability, this paper will rely in particular on studies using fetal heart rate variability (fHRV) to monitor the continued growth and health of both animal and human fetuses. In fact, fHRV is a non-invasive marker whose changes have been associated with ANS development, vagal modulation, systemic and neurological inflammatory reactions, and even fetal distress during labor.

Effects of maternal mental health on prenatal movement profiles in twins and singletons

AIM

Prenatal experiences, including maternal stress, depression and anxiety, form crucial building blocks affecting the maturation of the foetal central nervous system. Previous research has examined foetal movements without considering effects of maternal mental health factors critical for healthy foetal development. The aim of this research is to assess the effects of maternal mental health factors on foetal twin compared with singleton movement profiles.

METHOD

We coded foetal touch and head movements in 56 ultrasound scans, from a prospective opportunity sample of 30 mothers with a healthy pregnancy (mean gestational age 27.8 weeks for singleton and 27.2 for twins). At the ultrasound scan appointment, participants completed questionnaires assessing their stress, depression and anxiety.

RESULTS

Maternal depression increased foetal self-touch significantly. In foetal twins, maternal stress significantly decreased and maternal depression significantly increased other twin touch. Maternal mental health factors affected the head movements of twins significantly more than singletons, with maternal depression decreasing head movement frequency for twins significantly.

CONCLUSION

These results indicate that maternal mental health might have an impact on types of body schemata formed in utero, in twin compared with singleton pregnancies. Future research needs to examine whether these prenatal effects affect postnatal differences in body awareness.

Prenatal maternal psychological distress and fetal developmental trajectories: associations with infant temperament

Associations between prenatal maternal psychological distress and offspring developmental outcomes are well documented, yet relatively little research has examined links between maternal distress and development in utero, prior to postpartum influences. Fetal heart rate (FHR) parameters are established indices of central and autonomic nervous system maturation and function which demonstrate continuity with postnatal outcomes. This prospective, longitudinal study of 149 maternal-fetal pairs evaluated associations between prenatal maternal distress, FHR parameters, and dimensions of infant temperament. Women reported their symptoms of psychological distress at five prenatal visits, and FHR monitoring was conducted at the last three visits. Maternal report of infant temperament was collected at 3 and 6 months of age. Exposure to elevated prenatal maternal psychological distress was associated with higher late-gestation resting mean FHR (FHRM) among female but not male fetuses. Higher late-gestation FHRM was associated with lower infant orienting/regulation and with higher infant negative affectivity, and these associations did not differ by infant sex. A path analysis identified higher FHRM as one pathway by which elevated prenatal maternal distress was associated with lower orienting/regulation among female infants. Findings suggest that, for females, elevated maternal distress alters fetal development, with implications for postnatal function. Results also support the notion that, for both sexes, individual differences in regulation emerge prenatally and are maintained into infancy. Collectively, these findings underscore the utility of direct assessment of development in utero when examining if prenatal experiences are carried forward into postnatal life.

Sleep, Little Baby: The Calming Effects of Prenatal Speech Exposure on Newborns' Sleep and Heartrate

In a pilot study, 34 fetuses were stimulated daily with a maternal spoken nursery rhyme from week 34 of gestation onward and re-exposed two and five weeks after birth to this familiar, as well as to an unfamiliar rhyme, both spoken with the maternal and an unfamiliar female voice. During auditory stimulation, newborns were continuously monitored with polysomnography using video-monitored hdEEG. Afterward, changes in sleep–wake-state proportions during familiar and unfamiliar voice stimulation were analyzed. Our preliminary results demonstrate a general calming effect of auditory stimulation exclusively in infants who were prenatally “familiarized” with a spoken nursery rhyme, as evidenced by less waking states, more time spent in quiet (deep) sleep, and lower heartrates. A stimulation naïve group, on the other hand, demonstrated no such effects. Stimulus-specific effects related to the familiarity of the prenatally replayed voice or rhyme were not evident in newborns. Together, these results suggest “fetal learning” at a basic level and point to a familiarization with auditory stimuli prior to birth, which is evident in the first weeks of life in behavioral states and heartrate physiology of the newborn.

Correlation between human nervous system development and acquisition of fetal skills: An overview

Understanding the association between fetal nervous system structure and functioning should be an important goal in neurodevelopmental sciences, especially when considering the emerging knowledge regarding the importance of prenatal onset. Intrauterine development of the human central nervous system consists of specific processes: neurogenesis, neuronal migration, synaptogenesis, and myelination. However, as extensively shown by the neurobehavioral studies in the last century, the development of the central nervous system involves both structure and functioning. It is now recognised that the developing motor and sensory systems are able to function long before they have completed their neural maturation and that the intrauterine experience contributes to neurobehavioral development. This review analyzes the recent literature, looking at the association between the human nervous system maturation and fetal behavior. This article will follow the development and skill acquisition of the anatomical nervous system across the three trimesters of the gestation period.

Fetal Origin of Sensorimotor Behavior

The aim of this article is to track the fetal origin of infants' sensorimotor behavior. We consider development as the self-organizing emergence of complex forms from spontaneously generated activity, governed by the innate capacity to detect and memorize the consequences of spontaneous activity (contingencies), and constrained by the sensory and motor maturation of the body. In support of this view, we show how observations on fetuses and also several fetal experiments suggest that the fetus's first motor activity allows it to feel the space around it and to feel its body and the consequences of its movements on its body. This primitive motor babbling gives way progressively to sensorimotor behavior which already possesses most of the characteristics of infants' later behavior: repetition of actions leading to sensations, intentionality, some motor control and oriented reactions to sensory stimulation. In this way the fetus can start developing a body map and acquiring knowledge of its limited physical and social environment.

Fetal Development: Voice Processing in Normotensive and Hypertensive Pregnancies

Recent observation of maternal voice recognition provides evidence of rudimentary memory and learning in healthy term fetuses. However, such higher order auditory processing has not been examined in the presence of maternal hypertension, which is associated with reduced and/or impaired uteroplacental blood flow. In this study, voice processing was examined in 40 fetuses (gestational ages of 33 to 41 weeks) of hypertensive and normotensive women. Fetuses received 2 min of no sound, 2 min of a tape-recorded story read by their mothers or by a female stranger, and 2 min of no sound while fetal heart rate was recorded. Results demonstrated that fetuses in the normotensive group had heart rate accelerations during the playing of their mother's voice, whereas the response occurred in the hypertensive group following maternal voice offset. Across all fetuses, a greater fetal heart rate change was observed when the amniotic fluid index was above compared to below the median (i.e., 150 mm), indicating that amniotic fluid volume may be an independent moderator of fetal auditory sensitivity. It was concluded that differential fetal responding to the mother's voice in pregnancies complicated by maternal hypertension may reflect functional elevation of sensorineural threshold or a delay in auditory system maturation, signifying functional differences during fetal life or subtle differences in the development of the central nervous system.

Ultrasonographic Investigation of Human Fetus Responses to Maternal Communicative and Non-communicative Stimuli

During pregnancy fetuses are responsive to the external environment, specifically to maternal stimulation. During this period, brain circuits develop to prepare neonates to respond appropriately. The detailed behavioral analysis of fetus’ mouth movements in response to mothers’ speech may reveal important aspects of their sensorimotor and affective skills; however, to date, no studies have investigated this response. Given that newborns at birth are capable of responding with matched behaviors to the social signals emitted by the caregiver, we hypothesize that such precocious responses could emerge in the prenatal period by exploiting infants’ sensitivity to their mother’s voice. By means of a two-dimensional (2D) ultrasonography, we assessed whether fetuses at 25 weeks of gestation, showed a congruent mouthmotor response to maternal acoustic stimulation. Mothers were asked to provide different stimuli, each characterized by a different acoustic output (e.g., chewing, yawning, nursery rhymes, etc.) and we recorded the behavioral responses of 29 fetuses. We found that, when mothers sang the syllable LA in a nursery rhyme, fetuses significantly increased mouth openings. Other stimuli provided by the mother did not produce other significant changes in fetus’ behavior. This finding suggests that fetuses are sensitive only to specific maternal vocalizations (LA) and that fetal matched responses are rudimentary signs of early mirroring behaviors that become functional in the postnatal period. In conclusion, fetuses seem to be predisposed to respond selectively to specific maternal stimuli. We propose that such responses may play a role in the development of behavioral and emotional attunement with their mothers long before birth.

Ultrasound observations of subtle movements: a pilot study comparing foetuses of smoking and nonsmoking mothers

AIM

One way to assess foetal health of smokers is to ask mothers to count perceived movements, an unreliable method hiding differences in prenatal development. The aim of this pilot study was to assess subtle foetal movements in ultrasound scans and establish whether they differ in foetuses of mothers who smoked and nonsmoking mothers.

METHODS

This longitudinal pilot study recruited twenty mothers (16 nonsmoking; 4 smoking) scanned four times from 24 to 36 weeks gestation (80 ultrasound scans). Two types of fine-grained movements were coded offline and analysed using a Poisson log-linear mixed model.

RESULTS

Foetuses of smoking mothers showed a significantly higher rate of mouth movements compared to foetuses of nonsmoking mothers (p = 0.02), after controlling for maternal stress and depression. As pregnancy progressed, these differences between the smoking and nonsmoking groups widened. Differences between the two groups in the rate of foetal facial self-touch remained constant as pregnancy progressed and were borderline significant (p = 0.07).

CONCLUSION

Rates of foetal mouth movement and facial self-touch differ significantly between smokers and nonsmokers. A larger study is needed to confirm these results and to investigate specific effects, including the interaction of maternal stress and smoking. Additionally, the feasibility of this technique for clinical practice should be assessed.

Spinal mediation of motor learning and memory in the rat fetus

Fetal rats can alter patterns of interlimb coordination after experience with a yoke that links two legs together. Yoke training results in a pronounced increase in conjugate limb movements (CLM). To determine whether yoke motor learning is mediated by spinal cord circuitry, fetal subjects at embryonic Day 20 (E20) received yoke training after mid-thoracic spinal cord transection or sham surgery. Both spinal and sham-treated fetuses exhibited an increase in CLM during training. In a second experiment, fetuses received initial yoke training, then were transected or sham treated before a 2nd training. Spinal and sham fetuses that were yoked during both training sessions exhibited a more rapid rise in CLM than those yoked only in the later session. These findings indicate that motor learning in fetal rats can be supported by spinal cord circuitry alone, and that savings implies a form of motor memory localized in the spinal cord.

Fetal response to maternal hunger and satiation - novel finding from a qualitative descriptive study of maternal perception of fetal movements

Background

Maternal perception of decreased fetal movements is a specific indicator of fetal compromise, notably in the context of poor fetal growth. There is currently no agreed numerical definition of decreased fetal movements, with the subjective perception of a decrease on the part of the mother being the most significant definition clinically. Both qualitative and quantitative aspects of fetal activity may be important in identifying the compromised fetus. Yet, how pregnant women perceive and describe fetal activity is under-investigated by qualitative means. The aim of this study was to explore normal fetal activity, through first-hand descriptive accounts by pregnant women.

Methods

Using qualitative descriptive methodology, interviews were conducted with 19 low-risk women experiencing their first pregnancy, at two timepoints in their third trimester. Interview transcripts were later analysed using qualitative content analysis and patterns of fetal activity identified were then considered along-side the characteristics of the women and their birth outcomes.

Results

This paper focuses on a novel finding; the description by pregnant women of fetal behaviour indicative of hunger and satiation. Full findings will be presented in later papers. Most participants (74% 14 of 19) indicated mealtimes were a time of increased fetal activity. Eight participants provided detailed descriptions of increased activity around meals, with seven (37% 7 of 19) of these specifying increased fetal activity prior to meals or in the context of their own hunger. These movements were interpreted as a fetal demand for food often prompting the mother to eat. Interestingly, the women who described increased fetal activity in the context of hunger subsequently gave birth to smaller infants (mean difference 364 gm) than those who did not describe a fetal response to hunger.

Conclusions

Food seeking behaviour may have a pre-birth origin. Maternal-fetal interaction around mealtimes could constitute an endocrine mediated communication, in the interests of maintaining optimal intrauterine conditions. Further research is warranted to explore this phenomenon and the potential influence of feeding on the temporal organisation of fetal activity in relation to growth.

Development of auditory-specific brain rhythm in infants

Human infants rapidly develop their auditory perceptual abilities and acquire culture-specific knowledge in speech and music in the second 6 months of life. In the adult brain, neural rhythm around 10 Hz in the temporal lobes is thought to reflect sound analysis and subsequent cognitive processes such as memory and attention. To study when and how such rhythm emerges in infancy, we examined electroencephalogram (EEG) recordings in infants 4 and 12 months of age during sound stimulation and silence. In the 4-month-olds, the amplitudes of narrowly tuned 4-Hz brain rhythm, recorded from bilateral temporal electrodes, were modulated by sound stimuli. In the 12-month-olds, the sound-induced modulation occurred at faster 6-Hz rhythm at temporofrontal locations. The brain rhythms in the older infants consisted of more complex components, as even evident in individual data. These findings suggest that auditory-specific rhythmic neural activity, which is already established before 6 months of age, involves more speed-efficient long-range neural networks by the age of 12 months when long-term memory for native phoneme representation and for musical rhythmic features is formed. We suggest that maturation of distinct rhythmic components occurs in parallel, and that sensory-specific functions bound to particular thalamo-cortical networks are transferred to newly developed higher-order networks step by step until adult hierarchical neural oscillatory mechanisms are achieved across the whole brain.

Fetal behavior in smoking compared to non-smoking pregnant women

OBJECTIVE

To determine the effects of maternal smoking on fetal spontaneous behavior and auditory processing.

METHODS

38 fetuses of smoking (n=18) and non-smoking (n=20) mothers, stratified by gestational age (<37, >or=37 weeks GA), were examined at least 1h following smoking. Observations included spontaneous fetal heart rate (FHR; 20 min) and body movements (20 min) followed by a 2 min audiotape of the mother reading a story while FHR and body movements were recorded.

RESULTS

There were no differences in spontaneous behaviors; full-term fetuses showed a FHR acceleration and body movement during the mother's voice. A FHR response following voice offset was limited to fetuses less than 37 weeks GA of non-smoking mothers.

CONCLUSION

Fetuses less than 37 weeks GA of mothers who smoke throughout pregnancy have a delayed onset of response to the maternal voice, a subtle difference which may have implications for later language development for prematurely born infants which needs further investigation.

Emergence and development of embodied cognition: a constructivist approach using robots

A constructivist approach to cognition assumes the minimal and the simplest set of initial principles or mechanisms, embeds them in realistic circumstances, and lets the entire system evolve under close observation. This paper presents a line of research along this approach trying to connect embodiment to social cognition. First, we show that a mere physical body, when driven toward some task goal, provides a clear information structure, for action execution and perception. As a mechanism of autonomous exploration of such structure, "embodiment as a coupled chaotic field" is proposed, with experiments showing emergent and adaptive behavior. Scaling up the principles, a simulation of the fetal/neonatal motor development is presented. The musculo-skeletal system, basic nervous system, and the uterus environment are simulated. The neural-body dynamics exhibit spontaneous exploration of a variety of motor patterns. Lastly, a robotic experiment is presented to show that visual-motor self-learning can lead to neonatal imitation.

Auditory processing deficits in growth restricted fetuses affect later language development

An increased risk for language deficits in infants born growth restricted has been reported in follow-up studies for more than 20 years, suggesting a relation between fetal auditory system development and later language learning. Work with animal models indicate that there are at least two ways in which growth restriction could affect the development of auditory perception in human fetuses: a delay in myelination or conduction and an increase in sensorineural threshold. Systematic study of auditory function in growth restricted human fetuses has not been reported. However, results of studies employing low-risk fetuses delivering as healthy full-term infants demonstrate that, by late gestation, the fetus can hear, sound properties modulate behavior, and sensory information is available from both inside (e.g., maternal vascular) and outside (e.g., noise, voices, music) of the maternal body. These data provide substantive evidence that the auditory system is functioning and that environmental sounds are available for shaping neural networks and laying the foundation for language acquisition before birth. We hypothesize that fetal growth restriction affects auditory system development, resulting in atypical auditory information processing in growth restricted fetuses compared to healthy, appropriately-grown-for-gestational-age fetuses. Speech perception that lays the foundation for later language competence will differ in growth restricted compared to normally grown fetuses and be associated with later language abilities.

Early motor development from partially ordered neural-body dynamics: experiments with a cortico-spinal-musculo-skeletal model

Early human motor development has the nature of spontaneous exploration and boot-strap learning, leading to open-ended acquisition of versatile flexible motor skills. Since dexterous motor skills often exploit body-environment dynamics, we formulate the developmental principle as the spontaneous exploration of consistent dynamical patterns of the neural-body-environment system. We propose that partially ordered dynamical patterns emergent from chaotic oscillators coupled through embodiment serve as the core driving mechanism of such exploration. A model of neuro-musculo-skeletal system is constructed capturing essential features of biological systems. It consists of a skeleton, muscles, spindles, tendon organs, spinal circuits, medullar circuits (CPGs), and a basic cortical model. Through a series of experiments with a minimally simple body model, it is shown that the model has the capability of generating partially ordered behavior, a mixture of chaotic exploration and ordered entrained patterns. Models of self-organizing cortical areas for primary somatosensory and motor areas are introduced. They participate in the explorative learning by simultaneously learning and controlling the movement patterns. A scaled up version of the model, a human infant model, is constructed and put through preliminary experiments. Some meaningful motor behavior emerged including rolling over and crawling-like motion. The results show the possibility that a rich variety of meaningful behavior can be discovered and acquired by the neural-body dynamics without pre-defined coordinated control circuits.

Evidence of early development of action planning in the human foetus: a kinematic study

The aim of the present study was to investigate whether foetal hand movements are planned and how they are executed. We performed a kinematic analysis of hand movements directed towards the mouth and the eyes in the foetuses of eight women with normally evolving pregnancies. At 14, 18 and 22 weeks of gestation, eight foetuses underwent a 20-min four-dimensional-ultrasound session. The video recordings for these movements were then imported into in-house software developed to perform kinematic analysis. We found that spatial and temporal characteristics of foetal movements are by no means uncoordinated or unpatterned. By 22 weeks of gestation the movements seem to show the recognizable form of intentional actions, with kinematic patterns that depend on the goal of the action, suggesting a surprisingly advanced level of motor planning.

Foetal response to music and voice

OBJECTIVE

To examine whether prenatal exposure to music and voice alters foetal behaviour and whether foetal response to music differs from human voice.

SUBJECTS AND METHODS

A prospective observational study was conducted in 20 normal term pregnant mothers. Ten foetuses were exposed to music and voice for 15 s at different sound pressure levels to find out the optimal setting for the auditory stimulation. Music, voice and sham were played to another 10 foetuses via a headphone on the maternal abdomen. The sound pressure level was 105 db and 94 db for music and voice, respectively. Computerised assessment of foetal heart rate and activity were recorded. 90 actocardiograms were obtained for the whole group. One way anova followed by posthoc (Student-Newman-Keuls method) analysis was used to find if there is significant difference in foetal response to music and voice versus sham.

RESULTS

Foetuses responded with heart rate acceleration and motor response to both music and voice. This was statistically significant compared to sham. There was no significant difference between the foetal heart rate acceleration to music and voice.

CONCLUSION

Prenatal exposure to music and voice alters the foetal behaviour. No difference was detected in foetal response to music and voice.

Conjugate limb coordination after experience with an interlimb yoke: evidence for motor learning in the rat fetus

This study investigated the capacity of the E20 rat fetus to adaptively alter patterns of interlimb coordination in a prenatal model of motor learning. Fetal limb movement was manipulated with an interlimb yoke, consisting of a fine thread attached at the ankles, which created a physical linkage between two limbs. Exposure to the yoke resulted in a gradual increase in conjugate movements of the yoked limbs during a 30-min training period, which persisted after removal of the yoke. Training effects were evident when the yoke was applied to two hindlimbs, two forelimbs, or a homolateral forelimb-hindlimb pair. A savings in the rate of acquisition also was observed when fetuses experienced yoke training in a second session. These data argue that the rat fetus can respond to kinesthetic feedback resulting from variation in motor performance, which suggests that experience contributes to the development of coordinated motor behavior before birth.

Comparison of fetal behavior in low- and high-risk pregnancies

Meta-analyses were conducted on archival data of human fetal behavior to identify differential behavior among high-risk fetuses in pregnancies complicated by threatened preterm delivery, maternal hypertension or diabetes compared with low-risk fetuses in uneventful pregnancies, delivering as healthy, full-term infants. Data for a total of 493 fetuses (260 high risk, 233 low risk) from 23 weeks' gestation to term who participated in a study using a standardized protocol including observations of spontaneous and auditory-induced behavior were retrieved from our laboratory database. There were no differences in spontaneous behaviors when scored using clinical criteria for the nonstress test and biophysical profile; however, there were differences in the magnitude of the behaviors measured in the tests. Developmental differences were observed between those threatening to deliver early and the fetuses of hypertensive and diabetic mothers. The latter two groups differed little from one another but differed from low-risk fetuses in their response to auditory stimulation. We concluded that differences in behavior among high-risk groups suggest that atypical fetal behaviors may represent adaptation to condition specific insult rather than a generalized response to insult per se. The finding that high-risk fetuses showed atypical responses to auditory stimuli indicates a need to examine the relation between fetal auditory function and later language acquisition.

Maturation of fetal responses to music

Maturation of fetal response to music was characterized over the last trimester of pregnancy using a 5-minute piano recording of Brahms' Lullaby, played at an average of 95, 100, 105 or 110 dB (A). Within 30 seconds of the onset of the music, the youngest fetuses (28-32 weeks GA) showed a heart rate increase limited to the two highest dB levels; over gestation, the threshold level decreased and a response shift from acceleration to deceleration was observed for the lower dB levels, indicating attention to the stimulus. Over 5 minutes of music, fetuses older than 33 weeks GA showed a sustained increase in heart rate; body movement changes occurred at 35 weeks GA. These findings suggest a change in processing of complex sounds at around 33 weeks GA, with responding limited to the acoustic properties of the signal in younger fetuses but attention playing a role in older fetuses.

Development of interlimb movement synchrony in the rat fetus

In the fetal rat, interlimb synchrony is a prominent form of temporally organized spontaneous motor activity in which movement of different limbs occurs at nearly the same instant. In the present study, synchrony profiles were created for different pairwise combinations of limbs over the last 5 days of gestation. Observed rates of synchrony differentiated from randomized time series from Gestational Day 19 to Day 21 (E19-E21), with forelimb synchrony emerging earlier than that of other limb pairs. Synchrony profiles were elevated at the shortest intervals between successive limb movements, indicating that movements became more tightly coupled toward the end of gestation. Interlimb synchrony appears to be a robust method of quantifying fetal movement and may prove useful as a tool for assessing prenatal nervous system functioning.

Specific Newborn Individualized Developmental Care and Assessment Program movements are associated with acute pain in preterm infants in the neonatal intensive care unit

OBJECTIVE

The Newborn Individualized Developmental Care and Assessment Program (NIDCAP) is widely used in neonatal intensive care units and comprises 85 discrete infant behaviors, some of which may communicate infant distress. The objective of this study was to identify developmentally relevant movements indicative of pain in preterm infants.

METHODS

Forty-four preterm infants were assessed at 32 weeks' gestational age (GA) during 3 phases (baseline, lance/squeeze, and recovery) of routine blood collection in the neonatal intensive care unit. The NIDCAP and Neonatal Facial Coding System (NFCS) were coded from separate continuous bedside video recordings; mean heart rate (mHR) was derived from digitally sampled continuous electrographic recordings. Analysis of variance (phase x gender) with Bonferroni corrections was used to compare differences in NIDCAP, NFCS, and mHR. Pearson correlations were used to examine relationships between the NIDCAP and infant background characteristics.

RESULTS

NFCS and mHR increased significantly to lance/squeeze. Eight NIDCAP behaviors also increased significantly to lance/squeeze. Another 5 NIDCAP behaviors decreased significantly to lance/squeeze. Infants who had lower GA at birth, had been sicker, had experienced more painful procedures, or had greater morphine exposure showed increased hand movements indicative of increased distress.

CONCLUSIONS

Of the 85 NIDCAP behaviors, a subset of 8 NIDCAP movements were associated with pain. Particularly for infants who are born at early GAs, addition of these movements to commonly used measures may improve the accuracy of pain assessment.

Effects of experience on fetal voice recognition

The ability of human fetuses to recognize their own mother's voice was examined. Sixty term fetuses were assigned to one of two conditions during which they were exposed to a tape recording of their mother or a female stranger reading a passage. Voice stimuli were delivered through a loudspeaker held approximately 10 cm above the maternal abdomen and played at an average of 95 dB SPL. Each condition consisted of three 2-min periods: no stimulus, voice (mother or stranger), and no stimulus. Fetal heart rate increased in response to the mother's voice and decreased in response to the stranger's; both responses were sustained for 4 min. The finding of differential behavior in response to a familiar versus a novel voice provides evidence that experience influences fetal voice processing. It supports an epigenetic model of speech perception, presuming an interaction between genetic expression of neural development and species-specific experience.

An exploratory study of fetal behavior at 33 and 36 weeks gestational age in hypertensive women

The relationship between maternal blood pressure (BP) and fetal behaviors as well as differential spontaneous and vibroacoustic elicited fetal behaviors were examined in hypertensive (n = 21) compared to normotensive (n = 22) women at 33 and 36 weeks gestational age (GA). Maternal BP was negatively related to GA at birth and birth weight. On average, fetuses of hypertensive women were born 2 weeks earlier (38 weeks GA) and 340 g lighter. Maternal systolic BP was negatively related to the number of spontaneous body movements observed on ultrasound scan over 20 min and the magnitude of the fetal heart rate (FHR) acceleration elicited by a vibroacoustic stimulus. At 36 weeks GA, vibroacoustic stimulation elicited differential responding with fetuses in the hypertensive compared to the normotensive group having fewer body movements, a lower magnitude of FHR acceleration, and a lack of cardiac-body movement coupled responses. These findings suggest a relationship between maternal BP and fetal behaviors and differential functional development of sensory-motor response systems which need to be characterized in the subgroups of hypertensive disorders observed during pregnancy.

The role of prenatal stress in the etiology of developmental behavioural disorders

Substantial evidence from preclinical laboratory studies indicates that prenatal stress (PS) affects the hormonal and behavioural development of offspring. In the following review, the effects of PS in rodents and non-human primates on hypothalamic-pituitary-adrenal (HPA) reactivity to stress, morphological changes in the brain, motor behaviour and learning are surveyed. PS has been found to alter baseline and stress-induced responsivity of the HPA axis and levels and distribution of regulatory neurotransmitters, such as norepinepherine, dopamine, serotonin and acetylcholine and to modify key limbic structures. In rodents and non-human primates, PS affected learning, anxiety and social behaviour. The relevance of these findings to humans is discussed with respect to (a) the effect of administration of exogenous corticosteroids in pregnancy and (b) maternal state and trait anxiety during gestation and its relation to foetal autonomic regulation as putative predisposing factors in the pathogenesis of behavioural developmental delays in children.

Corticotrophin-releasing hormone and fetal responses in human pregnancy

During human pregnancy, maternal and fetal compartments of the human placenta produce and release corticotrophic-releasing hormone (CRH). Elevations of placental CRH are associated with decreased gestational length (including preterm delivery). The effects of elevated placental CRH on human fetal neurological development are not known. Pregnant women in the 31st and 32nd week of gestation consented to procedures for collection of blood and measurement of fetal heart rate (FHR) in response to a series of 40 vibro-acoustic stimuli (VAS). Measures of habituation and dishabituation were calculated from the FHR. All subjects were followed to delivery. Fetuses (N = 33) of women with highly elevated CRH were least responsive (p < .03) to stimulation after presentation of a novel (dishabituating) stimulus with control for parity, fetal gender, medical (antepartum) risk, and gestational length at term. In a larger sample (N = 156) a polynomial model predicted the pattern of FHR reactivity for the first 15 trials. Placental CRH concentration significantly predicted FHR reactivity after controlling for the effects of trial number, baseline FHR, inter-trial interval, and presence of uterine contractions. Increased maternal CRH levels were significantly related to the length of gestation after controlling for the effects of fetal gender, parity, and medical risk (p = .05). The relationship between length of gestation and FHR was not significant suggesting separate actions of CRH on these events. Elevated placental CRH appears to accelerate certain developmental events (gestational length) and may influence the fetal nervous system. The impaired fetal responses to novelty and increased arousal observed in this study suggest that neurological systems may be targets for placental CRH during sensitive developmental periods.