Spontaneous motor activity in the perinatal infant before and after birth: stability in individual differences

Rapid Eye Movement Sleep during Early Life: A Comprehensive Narrative Review

The ontogenetic sleep hypothesis suggested that rapid eye movement (REM) sleep is ontogenetically primitive. Namely, REM sleep plays an imperative role in the maturation of the central nervous system. In coincidence with a rapidly developing brain during the early period of life, a remarkably large amount of REM sleep has been identified in numerous behavioral and polysomnographic studies across species. The abundant REM sleep appears to serve to optimize a cerebral state suitable for homeostasis and inherent neuronal activities favorable to brain maturation, ranging from neuronal differentiation, migration, and myelination to synaptic formation and elimination. Progressively more studies in Mammalia have provided the underlying mechanisms involved in some REM sleep-related disorders (e.g., narcolepsy, autism, attention deficit hyperactivity disorder (ADHD)). We summarize the remarkable alterations of polysomnographic, behavioral, and physiological characteristics in humans and Mammalia. Through a comprehensive review, we offer a hybrid of animal and human findings, demonstrating that early-life REM sleep disturbances constitute a common feature of many neurodevelopmental disorders. Our review may assist and promote investigations of the underlying mechanisms, functions, and neurodevelopmental diseases involved in REM sleep during early life.

Fetal movements: A framework for antenatal conversations

BACKGROUND

Presentations for decreased fetal movements comprise a significant proportion of acute antenatal assessments. Decreased fetal movements are associated with increased likelihood of adverse pregnancy outcomes including stillbirth. Consensus-based guidelines recommend pregnant women routinely receive information about fetal movements, but practice is inconsistent, and the information shared is frequently not evidence-based. There are also knowledge gaps about the assessment and management of fetal movement concerns. Women have indicated that they would like more accurate information about what to expect regarding fetal movements.

DISCUSSION

Historically, fetal movement information has focussed on movement counts. This is problematic, as the number of fetal movements perceived varies widely between pregnant women, and no set number of movements has been established as a reliable indicator of fetal wellbeing. Of late, maternity care providers have also advised women to observe their baby's movement pattern, and promptly present if they notice a change. However, normal fetal movement patterns are rarely defined. Recently, a body of research has emerged relating to maternal perception of fetal movement features such as strength, presence of hiccups, and diurnal pattern as indicators of fetal wellbeing in addition to frequency.

CONCLUSION

Sharing comprehensive and gestation-appropriate information about fetal movements may be more satisfying for women, empowering women to identify for themselves when their baby is doing well, and importantly when additional assessment is needed. We propose a conversational approach to fetal movement information sharing, focusing on fetal movement strength, frequency, circadian pattern, and changes with normal fetal development, tailored to the individual.

Prenatal metal mixtures and sex-specific infant negative affectivity

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Prenatal exposure to metals has been associated with a range of adverse neurocognitive outcomes; however, associations with early behavioral development are less well understood. We examined joint exposure to multiple co-occurring metals in relation to infant negative affect, a stable temperamental trait linked to psychopathology among children and adults.

Predicting child temperament and behavior from the fetus

There remains little debate that the period before birth sets the stage for subsequent development, yet scant evidence exists showing continuity from characteristics of the individual fetus to characteristics of the child. This report examines, in two studies, whether baseline and evoked fetal neurobehavioral functioning are predictive of features of child temperament and behavior as reported by mothers when offspring were between 7 and 14 years old (M = 10.1 years). Study 1 utilizes data generated from 333 maternal-fetal pairs collected during an undisturbed condition during the second half of gestation in relation to the child temperament dimensions of behavioral inhibition and exuberance. Associations at 32 weeks gestation were detected between all features of fetal neurobehavior and behavioral inhibition. In adjusted models, slower fetal heart rate and less fetal movement were associated with significant unique variance in predicting higher levels of childhood behavioral inhibition. No associations were detected for exuberance. Study 2 focuses on the association of evoked fetal reactivity and recovery to induced maternal arousal with subsequent child behavioral difficulties in a subset of the full sample (n = 130). Greater recovery in fetal heart rate following maternal stimulation was predictive of fewer behavioral difficulties and more prosocial behavior in childhood. Results from both studies provide support for gestational origins of core individual differences that portend childhood outcomes with foundational reactivity and regulatory components.

Impact of maternal prenatal smoking on fetal to infant neurobehavioral development

Despite recent emphasis on the profound importance of the fetal environment in "programming" postnatal development, measurement of offspring development typically begins after birth. Using a novel coding strategy combining direct fetal observation via ultrasound and actocardiography, we investigated the impact of maternal smoking during pregnancy (MSDP) on fetal neurobehavior; we also investigated links between fetal and infant neurobehavior. Participants were 90 pregnant mothers and their infants (52 MSDP-exposed; 51% minorities; ages 18-40). Fetal neurobehavior at baseline and in response to vibro-acoustic stimulus was assessed via ultrasound and actocardiography at M = 35 weeks gestation and coded via the Fetal Neurobehavioral Assessment System (FENS). After delivery, the NICU Network Neurobehavioral Scale was administered up to seven times over the first postnatal month. MSDP was associated with increased fetal activity and fetal limb movements. Fetal activity, complex body movements, and cardiac-somatic coupling were associated with infants' ability to attend to stimuli and to self-regulate over the first postnatal month. Furthermore, differential associations emerged by MSDP group between fetal activity, complex body movements, quality of movement, and coupling, and infant attention and self-regulation. The present study adds to a growing literature establishing the validity of fetal neurobehavioral measures in elucidating fetal programming pathways.

Neuroimaging perspectives on fetal motor behavior

We are entering a new era of understanding human development with the ability to perform studies at the earliest time points possible. There is a substantial body of evidence to support the concept that early motor behaviour originates from supraspinal motor centres, reflects neurological integrity, and that altered patterns of behaviour precede clinical manifestation of disease. Cine Magnetic Resonance Imaging (cineMRI) has established its value as a novel method to visualise motor behaviour in the human fetus, building on the wealth of knowledge gleaned from ultrasound based studies. This paper presents a state of the art review incorporating findings from human and preclinical models, the insights from which, we propose, can proceed a reconceptualisation of fetal motor behaviour using advanced imaging techniques. Foremost is the need to better understand the role of the intrauterine environment, and its inherent unique set of stimuli that activate sensorimotor pathways and shape early brain development. Finally, an improved model of early motor development, combined with multimodal imaging, will provide a novel source of in utero biomarkers predictive of neurodevelopmental disorders.

STUDIES IN FETAL BEHAVIOR: REVISITED, RENEWED, AND REIMAGINED

Among the earliest volumes of this monograph series was a report by Lester Sontag and colleagues, of the esteemed Fels Institute, on the heart rate of the human fetus as an expression of the developing nervous system. Here, some 75 years later, we commemorate this work and provide historical and contemporary context on knowledge regarding fetal development, as well as results from our own research. These are based on synchronized monitoring of maternal and fetal parameters assessed between 24 and 36 weeks gestation on 740 maternal-fetal pairs compiled from eight separate longitudinal studies, which commenced in the early 1990s. Data include maternal heart rate, respiratory sinus arrhythmia, and electrodrmal activity and fetal heartrate, motor activity, and their integration. Hierarchical linear modeling of developmental trajectories reveals that the fetus develops in predictable ways consistent with advancing parasympathetic regulation. Findings also include:within-fetus stability (i.e., preservation of rank ordering over time) for heart rate, motor, and coupling measures; a transitional period of decelerating development near 30 weeks gestation; sex differences in fetal heart rate measures but not in most fetal motor activity measures; modest correspondence in fetal neurodevelopment among siblings as compared to unrelated fetuses; and deviations from normative fetal development in fetuses affected by intrauterine growth restriction and other conditions. Maternal parameters also change during this period of gestation and there is evidence that fetal sex and individual variation in fetal neurobehavior influence maternal physio-logical processes and the local intrauterine context. Results are discussed within the framework of neuromaturation, the emergence of individual differences, and the bidirectional nature of the maternal-fetal relationship.We pose a number of open questions for future research. Although the human fetus remains just out of reach, new technologies portend an era of accelerated discovery of the earliest period of development

Fetal heart rate and motor activity associations with maternal organochlorine levels: results of an exploratory study

Contemporaneous associations between circulating maternal organochlorines (OCs) and measures of fetal heart rate and motor activity were evaluated. A panel of 47 OCs, including pesticides and polychlorinated biphenyls (PCBs), was analyzed from serum of 50 pregnant women at 36 weeks gestation. Data were empirically reduced into four factors and six individual compounds. All participants had detectable concentrations of at least one-quarter of the assayed OCs and, in general, higher socioeconomic level was associated with higher OC concentrations. Fetal heart rate measures were not consistently associated with maternal OCs. In contrast, one or more indicators of greater fetal motor activity were significantly associated with higher levels of the DDT and low chlorinated OC factors and five of the six individual compounds (heptachlor epoxide, trans nonachlor, oxychlordane, and PCBs 18 and 52). This preliminary demonstration of associations between fetal motor activity and maternal concentrations of persistent and pervasive environmental contaminants suggests that fetal assessment may be useful in ascertaining the potential early effects of these compounds on development.

Fetal Behavior and Heart Rate in Twin Pregnancy: A Review

Fetal movements and fetal heart rate (FHR) are well-established markers of fetal well-being and maturation of the fetal central nervous system. The purpose of this paper is to review and discuss the available knowledge on fetal movements and heart rate patterns in twin pregnancies. There is some evidence for an association or similarity in fetal movement incidences or FHR patterns between both members of twin pairs. However, the temporal occurrence of these patterns seems to be for the most part asynchronous, especially when stricter criteria are used to define synchrony. The available data suggest that fetal behavior is largely independent of sex combination, fetal position, and presentation. Conversely, chorionicity appears to have some influence on fetal behavior, mainly before 30 weeks of gestation. There is preliminary evidence for the continuity of inter-individual differences in fetal activity and FHR patterns over pregnancy. Comparisons between studies are limited by large methodological differences and absence of uniform concepts and definitions. Future studies with high methodological quality are needed to provide a more comprehensive knowledge of normal fetal behavior in twin pregnancy.

Patterns of fetal heart rate response at ∼30 weeks gestation predict size at birth

There is evidence that fetal exposure to maternal stress is associated with adverse birth outcomes. Less is known about the association between fetal responses to a stressor and indicators of fetal maturity and developmental outcomes. The purpose of the present study was to determine whether fetal heart rate (FHR) patterns in response to a startling stimulus at ∼30 weeks of gestation were associated with gestational age at birth and birth weight. FHR was measured in 156 maternal-fetal dyads following a vibroacoustic stimulus. All pregnancies were singleton intrauterine pregnancies in English-speaking women who were primarily married, middle class, White and at least 18 years of age. Group-based trajectory modeling identified five groups of fetuses displaying distinctive longitudinal trajectories of FHR response to the startling stimulus. The FHR group trajectories were significantly associated with birth weight percentile (P < 0.01) even after controlling for estimated fetal weight at the time of assessment and parity, which are the known factors influencing birth weight (P < 0.01). Post hoc analyses indicated that two groups accounted for the association between FHR patterns and birth weight. The group (n = 23) with the lowest birth weight exhibited an immediate FHR deceleration followed by an immediate acceleration that does not recover. An FHR pattern characterized by immediate and fast acceleration to the peak and a slow discovery to baseline was associated with the highest birth weight. This is the first direct evidence showing that low birth weight and the resulting neurological consequences may have their origins in early fetal development.

Maternal voice and short-term outcomes in preterm infants

This study explored effects of exposure to maternal voice on short-term outcomes in very low birth weight preterm infants cared for within an neonatal intensive care unit (NICU) without an ongoing program of developmental care. Using a comparative design, 53 infants born during their 27th to 28th postmenstrual week were sampled by convenience. Experimental groups were exposed to maternal voice during two developmental time periods. Group 1 listened to a recording of their mothers reciting a rhyme from 28 to 34 postmenstrual weeks. Group 2 waited 4 weeks and heard the recording from 32 to 34 weeks. The control group received routine care. The primary analysis of combined experimental groups compared to the control group revealed that the experimental infants experienced significantly fewer episodes of feeding intolerance and achieved full enteral feeds quicker compared to the control group. Further, in an analysis evaluating all three groups separately, it was noted that Group 1 experienced significantly fewer episodes of feeding intolerance compared to the control group. Study findings warrant further investigation of exposure to maternal voice and the developmental timing at which exposure is begun.

Implementation of uniform information on fetal movement in a Norwegian population reduced delayed reporting of decreased fetal movement and stillbirths in primiparous women - a clinical quality improvement

BACKGROUND

Delayed maternal reporting of decreased fetal movement (DFM) is associated with adverse pregnancy outcomes. Inconsistent information on fetal activity to women during the antenatal period may result in delayed reporting of DFM. We aimed to evaluate an intervention of implementation of uniform information on fetal activity to women during the antenatal period.

METHODS

In a prospective before-and-after study, singleton women presenting DFM in the third trimester across 14 hospitals in Norway were registered. Outcome measures were maternal behavior regarding reporting of DFM, concerns and stillbirth. In addition, cross-sectional studies of all women giving birth were undertaken to assess maternal concerns about fetal activity, and population-based data were obtained from the Medical Birth Registry Norway.

RESULTS

Pre- and post-intervention cohorts included 19 407 and 46 143 births with 1 215 and 3 038 women with DFM respectively. Among primiparous women with DFM, a reduction in delayed reporting of DFM (>/=48 hrs) OR 0.61 (95% CI 0.47-0.81) and stillbirths OR 0.36 (95% CI 0.19-0.69) was shown in the post-intervention period. No difference was shown in rates of consultations for DFM or maternal concerns. Stillbirth rates and maternal behavior among women who were of non-Western origin, smokers, overweight or >34 years old were unchanged.

CONCLUSIONS

Uniform information on fetal activity provided to pregnant women was associated with a reduction in the number of primiparous women who delayed reporting of DFM and a reduction of the stillbirth rates for primiparous women reporting DFM. The information did not appear to increase maternal concerns or rate of consultation. Due to different imperfections in different clinical settings, further studies in other populations replicating these findings are required.

Prenatal antecedents of newborn neurological maturation

Fetal neurobehavioral development was modeled longitudinally using data collected at weekly intervals from 24 to 38 weeks gestation in a sample of 112 healthy pregnancies. Predictive associations between 3 measures of fetal neurobehavioral functioning and their developmental trajectories to neurological maturation in the first weeks after birth were examined. Prenatal measures included fetal heart rate (FHR) variability, fetal movement, and coupling between fetal motor activity and heart rate patterning; neonatal outcomes include a standard neurologic examination (n = 97) and brainstem auditory evoked potential (BAEP; n = 47). Optimality in newborn motor activity and reflexes was predicted by fetal motor activity, FHR variability, and somatic-cardiac coupling predicted BAEP parameters. Maternal pregnancy-specific psychological stress was associated with accelerated neurologic maturation.

Fetal motor activity and maternal cortisol

The contemporaneous association between maternal salivary cortisol and fetal motor activity was examined at 32 and 36 weeks gestation. Higher maternal cortisol was positively associated with the amplitude of fetal motor activity at 32 weeks, r(48) = .39, p < .01, and 36 weeks, r(77) = .27, p < .05, and the amount of time fetuses spent moving at 32 weeks during the 50 min observation period, r(48) = 33, p < .05. Observation of periods of unusually intense fetal motor activity were more common in fetuses of women with higher cortisol, Mann-Whitney U = 58.5. There were no sex differences in fetal motor activity, but the associations between maternal cortisol and fetal motor amplitude and overall movement were significantly stronger for male than female fetuses.

Maturation of the human fetal startle response: evidence for sex-specific maturation of the human fetus

Despite the evidence for early fetal experience exerting programming influences on later neurological development and health risk, very few prospective studies of human fetal behavior have been reported. In a prospective longitudinal study, fetal nervous system maturation was serially assessed by monitoring fetal heart rate (FHR) responses to vibroacoustic stimulation (VAS) in 191 maternal/fetal dyads. Responses were not detected at 26 weeks gestational age (GA). Sex-specific, age-characteristic changes in the FHR response to VAS were observed by 31 weeks' GA. Males showed larger responses and continued to exhibit maturational changes until 37 weeks' GA, females however, presented with a mature FHR startle response by 31 weeks' GA. The results indicate that there are different rates of maturation in the male and female fetuses that may have implications for sex-specific programming influences.

The Early Development of Gender Differences

This article reviews findings from anthropology, psychology, and other disciplines about the role of biological factors in the development of sex differences in human behavior, including biological theories, the developmental course of sex differences, and the interaction of biological and cultural gendering processes at different ages. Current evidence suggests that major biological influences on individual differences in human gender, to the extent that they exist, operate primarily in early development, during and especially prior to puberty. Biological effects are likely to be mediated by relatively simple processes, like temperament, which are then elaborated through social interactions (as with mother and peers) into more complex gendered features of adult personality. Biological anthropologists and psychologists interested in gender should direct more attention to understanding how social processes influence the development and function of the reproductive endocrine system.

Prenatal origins of temperamental reactivity in early infancy

BACKGROUND

Temperament theory has long considered individual differences in reactivity and regulation to be present at birth. Recent evidence suggests that such differences may be present prenatally and moderated by maternal emotionality.

AIMS

To determine whether induced maternal emotional activation generates a fetal response and whether observed fetal responsivity is associated with early infant temperament.

STUDY DESIGN

Women viewed an emotionally evocative labor and delivery documentary at 32 weeks gestation while physiological indices were evaluated and their infant's temperament was assessed at 6 weeks postnatal age.

SUBJECTS

Participants were 137 pregnant women and their infants.

OUTCOME MEASURES

Maternal physiological (heart rate and skin conductance) and fetal neurobehavioral (heart rate and motor activity) data were collected during gestation in response to the stimulus. Infant temperament (irritability and consolability) data were based on observational methods after birth.

RESULTS

Fetuses reacted to maternal viewing of the video with decreased heart rate variability, fewer motor bouts, and decreased motor activity. There was correspondence between the nature of individual maternal physiological responses to the full video, as well as phasic responses to a graphic birth scene, and fetal responsivity. Fetuses that reacted more intensively to maternal stimulation were significantly more likely to become infants that demonstrated greater irritability during a developmental examination at 6 weeks of age.

DISCUSSION

These results support the presumption that early postnatal temperamental characteristics emerge during the prenatal period.

Dyadic Intervention during Pregnancy? Treating Pregnant Women and Possibly Reaching the Future Baby

It is well established that postnatally, maternal psychopathology greatly increases a child's risk for emotional disorders. This article addresses the formative phase that precedes the mother–infant mutually regulating dyad. Biopsychological data presented here suggest that women's affective states during pregnancy—specifically depression, anxiety, and elevated life‐stress—are associated with subtle alterations in the neurobiological substrate of the fetus' emerging affect regulation system. The article moves to a general discussion of the emotional experience of pregnancy, and to the use of psychodynamic psychotherapy when problematic aspects of women's representational world lead to negative or dysregulated affect. Two case vignettes are presented: one described in brief and the other in greater detail. This kind of therapeutic intervention aims to achieve mood improvement, address women's emerging relationship with her baby, and potentially, influence the course of fetal development. Winnicott (1960) said there is no such thing as a baby alone; all the more so during pregnancy.

Prenatal predictors of infant temperament

Emerging data suggest that prenatal factors influence children's temperament. In 50 dyads, we examined fetal heart rate (FHR) activity and women's antenatal psychiatric illness as predictors of infant temperament at 4 months (response to novelty and the Infant Behavior Checklist). FHR change during maternal challenge was positively associated with observed infant motor reactivity to novelty (p = .02). The odds of being classified as high versus low motor among fetuses who had an increase in FHR during maternal stress was 11 times those who had a decrease in FHR (p = .0006). Antenatal psychiatric diagnosis was associated with an almost fourfold greater odds of having a high cry reactivity classification (p = .03). There also were modest associations between baseline FHR and maternal reports of infant temperament and between observed temperament and that based on mothers' reports. All of the infant results were found independent of the influence of women's postnatal anxiety. These data indicate that physiological markers of individual differences in infant temperament are identifiable in the fetal period, and possibly shaped by the prenatal environment.

Normal fetal motility: an overview

After 35 years of real-time two-dimensional sonography, and now that 4D sonography is within our grasp, this article presents an overview of present-day knowledge of normal fetal motility. A literature search was carried out on articles from 1970, using the keywords: 'fetal', 'movements', 'motility', 'movement patterns', 'ultrasound' and 'sonography'. Inclusion criteria were human studies and use of real-time sonography. Articles were screened for type of motor assessment procedure, in terms of whether they: specified movements for participating body parts (specific movement pattern, SMP), were qualitative (performance in terms of speed and amplitude), were quantitative, identified behavioral states, stated the duration of observation, and specified gestational age. We noted developmental milestones obtained for each study aim. One of four aims was identified for each article, depending on whether it focused on emergence, development, or continuity after birth of the movement patterns, or on the relationship of various motor aspects to other parameters that evaluate fetal condition, such as blood flow and fetal heart rate. A total of 109 relevant articles was identified, examining 9862 fetuses. Assessment was performed primarily with analysis of SMPs (89%); 52% also included non-SMPs (NSMPs), 78% included quantification, 24% assessment of quality, and 32% behavioral states. The duration of observation was 1 h or longer in 50% of the studies. The focus in 28 studies was on emergence, in 44 it was on development, in five it was on continuity and in 32 it was on relationship of the movements with other parameters of fetal well-being. A few milestones identified were determination of the strictly age-related emergence of SMPs and behavioral states, the highly reproducible quality of SMPs throughout gestation, the age-related trends in quantified SMPs, the continuity in quality and quantity after birth, and the close relationship between motility and heart-rate variability, flow parameters, and behavioral states. Periods of longest inactivity recorded before 20 weeks were 13 min; after 30 weeks they were 45 min. Much insight was obtained into the development of motility and its relationship to other parameters from those articles applying comparable assessment procedures. An assessment procedure with well-defined SMPs, qualitative and quantitative aspects of SMPs and NSMPs, and an observation period dependent on age are advocated for future research.

Neurobehavioral assessment before birth

The complexities of neurobehavioral assessment of the fetus, which can be neither directly viewed nor manipulated, cannot be understated. Impetus to develop methods for measuring fetal neurobehavioral development has been provided by the recognition that individual differences in neurobehavioral functioning do not originate with birth and acceptance of the key contribution of the antenatal period to postnatal life. Research has centered around four aspects of fetal functioning: heart rate, motor activity, behavioral state, and responsivity to stimulation. Longitudinal studies have revealed that the developmental trajectories of these characteristics parallel the developing nervous system, detected a transitional period between 28 and 32 weeks gestation, and established within-fetal stability during the second half of gestation. Despite the promise of fetal stimulation and habituation paradigms as measures of neural functioning, significant safety and ethical concerns exist. Construction of a unified fetal neurobehavioral scale is premature until a sufficient degree of normative data is available and the predictive validity of specific aspects of fetal neurobehavior to child developmental outcomes is better established.

Fetal state concordance predicts infant state regulation

Fetal state organization reflects the development of the central nervous system but may also portend individual differences in postnatal state organization. The goal of the present study was to determine the extent to which fetal state regulation, defined as the percentage of an observation period in which fetal heart rate and movement concordance was displayed, is associated with neonatal state regulation. Neonatal state regulation was evaluated through a standard neurobehavioral assessment at 2 weeks postpartum. Biobehavioral concordance was measured in 52 normally developing fetuses at 24, 30 and 36 weeks gestation using an actocardiograph; the neonatal assessment was administered to 41 of these as infants. Intrafetal stability in biobehavioral concordance did not emerge prior to 36 weeks. Fetuses with higher concordance at 36 weeks were infants that displayed better state regulation during the exam, including more alertness and orientation (r(35)=0.29), less cost of maintaining attention (r=0.36), less irritability (r=-0.41), better regulatory capacity (r=0.47), a greater range of available states (r=0.34), and were significantly more likely to maintain control during the most aversive portions of the exam F(1,31)=4.63, p<0.05). These results support fetal state as a stable individual attribute that is conserved across the prenatal and neonatal periods.

What does fetal movement predict about behavior during the first two years of life?

This study evaluated whether motor activity prior to birth is predictive of motor behavior and temperament in neonates, infants, and toddlers. Three measures of fetal motor activity (activity level, amplitude, and number of movements) were collected at 24, 30, and 36 weeks of gestation in 52 healthy fetuses using Doppler-based actography. Postnatal data collection included a neurobehavioral assessment at 2-weeks postpartum (n = 41), and laboratory-based behavioral observations at 1 and 2 years of age (ns = 35). Individual stability in motor activity was present during gestation. Predictive relations between fetal movement and neonatal behavior were inconsistent; significant but small positive associations were detected between motor behavior at 36 weeks and neonatal irritability and motor development. Fetal activity level at 36 weeks was positively associated with observed 1-year activity level for boys (but inversely related for girls) and maternal report of activity level at 2 years. Fetal movement was consistently and negatively predictive of distress to limitations at 1 year and behavioral inhibition at 2 years, accounting for 21 to 43% of the variance in these measures. Intrafetal variability in motor behavior makes this a relatively unstable metric for prediction to neonatal maturational outcomes, which are relatively constrained, but fetal motor activity appears to predict temperament attributes related to regulatory behaviors in early childhood.

Antenatal origins of individual differences in heart rate

This study examines prenatal-to-postnatal stability in heart rate and variability from mid-gestation through the first year of life. Fetal heart rate data were collected from 52 healthy fetuses at 24, 30, and 36 weeks gestation, and again at 2 weeks and 12 months of age. Fetal heart rate measures were stable during gestation and positively associated with neonatal and infant measures. Maternal pulse rate and oxygen saturation were moderately associated with fetal heart rate. Together, fetal cardiac (heart rate and variability) and maternal physiologic measures (blood pressure and oxygen saturation) explained 40 and 48% of the variance in heart rate and variability, respectively, at 1 year of age. These common measures of individual differences in autonomic function are enduring characteristics that originate during fetal development.