Cross-correlation of fetal cardiac and somatic activity as an indicator of antenatal neural development

Mapping Early Brain-Body Interactions: Associations of Fetal Heart Rate Variation with Newborn Brainstem, Hypothalamic, and Dorsal Anterior Cingulate Cortex Functional Connectivity

The autonomic nervous system (ANS) regulates the body's physiology, including cardiovascular function. As the ANS develops during the second to third trimester, fetal heart rate variability (HRV) increases while fetal heart rate (HR) decreases. In this way, fetal HR and HRV provide an index of fetal ANS development and future neurobehavioral regulation. Fetal HR and HRV have been associated with child language ability and psychomotor development behavior in toddlerhood. However, their associations with postbirth autonomic brain systems, such as the brainstem, hypothalamus, and dorsal anterior cingulate cortex (dACC), have yet to be investigated even though brain pathways involved in autonomic regulation are well established in older individuals. We assessed whether fetal HR and HRV were associated with the brainstem, hypothalamic, and dACC functional connectivity in newborns. Data were obtained from 60 pregnant individuals (ages 14-42) at 24-27 and 34-37 weeks of gestation using a fetal actocardiograph to generate fetal HR and HRV. During natural sleep, their infants (38 males and 22 females) underwent a fMRI scan between 40 and 46 weeks of postmenstrual age. Our findings relate fetal heart indices to brainstem, hypothalamic, and dACC connectivity and reveal connections with widespread brain regions that may support behavioral and emotional regulation. We demonstrated the basic physiologic association between fetal HR indices and lower- and higher-order brain regions involved in regulatory processes. This work provides the foundation for future behavioral or physiological regulation research in fetuses and infants.

Dose-Dependent Heart Rhythm Disturbance Occurring in Response to the Activation of Choline-Reactive Structures in Early Rat Ontogeny

The effect of dose-dependent activation of cholinoreactive structures on the severity of sinus bradycardia occurring in some intact newborn rats during the first weeks after birth was analyzed in non-narcotized one-day-old (P1) and 16-day-old (P16) rats. The parameters of low-amplitude bradycardic oscillations of heart rhythm in norm and after administration of the acetylcholinesterase inhibitor physostigmine (eserine) in different doses (¹/₁₀₀, ¹/₁₀, and ³/₄LD₅₀) to rats were studied. The maximum increase in the power of low-amplitude brady-cardic oscillations was achieved during moderate activation of cholinoreactive structures after injection of eserine in a dose of ¹/₁₀LD₅₀. Further increase in acetylcholine level led to disappearance of the sinus rhythm and development of pathological bradycardia. The data obtained indicate the immaturity of the mechanisms of heart rhythm regulation in rats immediately after birth. During activation of cholinoreactive structures, the severity of bradycardia oscillations increases exponentially at P1 and has an inverse exponential character at P16, which indicates a high risk of cardiac rhythmogenesis disorders and dysrhythmia development in newborn rats under conditions of excessive enhancement of cholinergic activation.

Prenatal origins of temperament: Fetal cardiac development & infant surgency, negative affectivity, and regulation/orienting

Temperament, i.e. individual differences in reactivity and self-regulation, emerges early in infancy; might temperament originate during fetal development? Mixed findings and methodological issues in the literature examining this consideration limit our understanding of the continuity between these fetal indices and infant temperament. The primary aims of the current study were to improve on published studies by (a) using standardized and well-accepted fetal cardiac (actocardiograph) and infant temperament measures (the Infant Behavior Questionnaire-Revised; IBQ-R) (b) expanding fetal assessments to include coupling (the cross correlation of heart rate with movement), and (c) examining a diverse sample to determine if findings of associations between fetal neurobehavior and infant temperament generalize beyond cohorts that are demographically well-resourced and predominantly white. Building on theory and empirical findings, we hypothesized that (1) FHR would be positively associated with Surgency and Negative Affectivity, (2) FHRV would be positively associated with Surgency, and Regulation/Orienting and inversely associated with Negative Affectivity, and (3) fetal coupling would be positively associated with Regulation/Orienting and Surgency and inversely associated with Negative Affectivity. We collected 20 min of fetal data (m gestational age = 34.42 weeks) and mothers completed the IBQ-R (n = 90 women; 60 % non-Caucasian race; 63 % Latina ethnicity). We found that FHR was positively associated with Negative Affectivity but not associated with Surgency (or Regulation/Orienting). FHRV was inversely associated with Surgency but not associated with Negative Affectivity or Regulation/Orienting. Coupling was positively associated with Regulation/Orienting and Surgency but not associated with Negative Affectivity. Our findings, from a more diverse sample and with established measures, provide further evidence that individual differences in reactivity and regulation can be identified in the in-utero period and show theory-based continuity to specific infant temperament constructs.

Effects of Prenatal Exposure to Alcohol and Smoking on Fetal Heart Rate and Movement Regulation

Negative associations of prenatal tobacco and alcohol exposure (PTE and PAE) on birth outcomes and childhood development have been well documented, but less is known about underlying mechanisms. A possible pathway for the adverse fetal outcomes associated with PTE and PAE is the alteration of fetal autonomic nervous system development. This study assessed PTE and PAE effects on measures of fetal autonomic regulation, as quantified by heart rate (HR), heart rate variability (SD-HR), movement, and HR-movement coupling in a population of fetuses at ≥ 34 weeks gestational age. Participants are a subset of the Safe Passage Study, a prospective cohort study that enrolled pregnant women from clinical sites in Cape Town, South Africa, and the Northern Plains region, United States. PAE was defined by six levels: no alcohol, low quit early, high quit early, low continuous, moderate continuous, and high continuous; while PTE by 4 levels: no smoking, quit early, low continuous, and moderate/high continuous. Linear regression analyses of autonomic measures were employed controlling for fetal sex, gestational age at assessment, site, maternal education, household crowding, and depression. Analyses were also stratified by sleep state (1F and 2F) and site (South Africa, N = 4025, Northern Plains, N = 2466). The final sample included 6491 maternal-fetal-dyad assessed in the third trimester [35.21 ± 1.26 (mean ± SD) weeks gestation]. PTE was associated with a decrease in mean HR in state 2F, in a dose dependent fashion, only for fetuses of mothers who continued smoking after the first trimester. In state 1F, there was a significant increase in mean HR in fetuses whose mother quit during the first trimester. This effect was driven by the Norther Plains cohort. PTE was also associated with a significant reduction in fetal movement in the most highly exposed group. In South Africa a significant increase in mean HR both for the high quit early and the high continuous group was observed. In conclusion, this investigation addresses a critical knowledge gap regarding the relationship between PTE and PAE and fetal autonomic regulation. We believe these results can contribute to elucidating mechanisms underlying risk for adverse outcomes.

Fetal heart rate during maternal sleep

Despite prolonged and cumulative exposure during gestation, little is known about the fetal response to maternal sleep. Eighty-four pregnant women with obesity (based on pre-pregnancy BMI) participated in laboratory-based polysomnography (PSG) with continuous fetal electrocardiogram monitoring at 36 weeks gestation. Multilevel modeling revealed both correspondence and lack of it in maternal and fetal heart rate patterns. Fetal heart rate (fHR) and variability (fHRV), and maternal heart rate (mHR) and variability (mHRV), all declined during the night, with steeper rates of decline prior to 01:00. fHR declined upon maternal sleep onset but was not otherwise associated with maternal sleep stage; fHRV differed during maternal REM and NREM. There was frequent maternal waking after sleep onset (WASO) and fHRV and mHRV were elevated during these episodes. Cross-correlation analyses revealed little temporal coupling between maternal and fetal heart rate, except during WASO, suggesting that any observed associations in maternal and fetal heart rates during sleep are the result of other physiological processes. Implications of the maternal sleep context for the developing fetus are discussed, including the potential consequences of the typical sleep fragmentation that accompanies pregnancy.

Neonatal sleep development and early learning in infants with prenatal opioid exposure

The aim of this chapter is to examine the role of sleep and cognition in the context of the cumulative risk model examining samples of at-risk infants and maternal-infant dyads. The cumulative risk model posits that non-optimal developmental outcomes are the result of multiple factors in a child's life including, but not limited to, prenatal teratogenic exposures, premature birth, family socioeconomic status, parenting style and cognitions as well as the focus of this volume, sleep. We highlight poor neonatal sleep as both an outcome of perinatal risk as well as a risk factor to developing attentional and cognitive capabilities during early childhood. Outcomes associated with and contributing to poor sleep and cognition during infancy are examined in relation to other known risks in our clinical population. Implications of this research and recommendations for interventions for this population are provided.

Road Transport of Late-Pregnant Mares Advances the Onset of Foaling

Cortisol is involved in the initiation of parturition and we hypothesized that increased maternal cortisol release advances the onset of foaling. Transport is a stressor for horses and induces an increase in cortisol release. To determine stress effects on the time of foaling, late-pregnant mares were transported by road for 3 hours (n = 12) or remained in their stable as controls (n = 4). Starting on day 325 of gestation, saliva and blood samples were taken for cortisol and progestin analysis, respectively. Fetomaternal electrocardiograms were recorded repeatedly. Mares were checked for impending parturition and changes in precolostrum pH. When pH decreased to 6.5, mares were either transported or left untreated. After birth, saliva was collected repeatedly from mares and their foals and heart rate (HR) was recorded. Foals were checked for maturity and health. Gestation length was 337 ± 2 days in stressed and 336 ± 2 days in control mares. Cortisol concentration increased from 3.3 ± 0.9 to 8.4 ± 0.8 ng/mL in transported mares (P < .001) and remained constant in controls. Maternal HR and heart rate variability (HRV) did not differ between groups and neither fetal HR nor HRV changed in response to transport. In transported mares, time from precolostrum decrease to parturition was shorter (40 ± 10 hours) than the respective time in controls (134 ± 49 hours, P < .01). Neither duration of foaling nor times to first standing and suckling of foals or the postnatum increase in HR and decrease in HRV differed between groups. In conclusion, transport-induced maternal cortisol release may have advanced the onset of foaling.

Maternal prenatal stress phenotypes associate with fetal neurodevelopment and birth outcomes

Maternal prenatal stress influences offspring neurodevelopment and birth outcomes including the ratio of males to females born; however, there is limited understanding of what types of stress matter, and for whom. Using a data-driven approach with 27 variables from questionnaires, ambulatory diaries, and physical assessments collected early in the singleton pregnancies of 187 women, 3 latent profiles of maternal prenatal stress emerged that were differentially associated with sex at birth, birth outcomes, and fetal neurodevelopment. Most women (66.8%) were in the healthy group (HG); 17.1% were in the psychologically stressed group (PSYG), evidencing clinically meaningful elevations in perceived stress, depression, and anxiety; and 16% were in the physically stressed group (PHSG) with relatively higher ambulatory blood pressure and increased caloric intake. The population normative male:female secondary sex ratio (105:100) was lower in the PSYG (2:3) and PHSG (4:9), and higher in the HG (23:18), consistent with research showing diminished male births in maternal stress contexts. PHSG versus HG infants were born 1.5 wk earlier (P < 0.05) with 22% compared to 5% born preterm. PHSG versus HG fetuses had decreased fetal heart rate-movement coupling (P < 0.05), which may indicate slower central nervous system development, and PSYG versus PHSG fetuses had more birth complications, consistent with previous findings among offspring of women with psychiatric illness. Social support most strongly differentiated the HG, PSYG, and PHSG groups, and higher social support was associated with increased odds of male versus female births. Stress phenotypes in pregnant women are associated with male vulnerability and poor fetal outcomes.

Advanced automatic detection of fetal body movements from multichannel magnetocardiographic signals

OBJECTIVE

Both heart rate (HR) monitoring and detection and description of fetal movements provide essential information of the integrity of in utero development and fetal wellbeing. Our previously described method to identify movements from multichannel magnetocardiographic (MCG) recordings lacks of reliability in some cases. This work is aimed at the improvement of fetal movement detection by means of an advanced signal processing and validation strategy.

APPROACH

The previously proposed methodology of fetal body movement detection from MCG recordings using single space angle (SSA), min-max amplitude (MMA) and a measure of the overall signal strength across (RSS) was extended by moving correlation coefficient (MCC). The methodology was developed with respect to the discrimination between active and quiet sleep, validated by testing its coupling with HR accelerations in a total of 137 recordings lasting 30 min from 98 fetuses aged 34-38 weeks of gestation (WGA) of normal pregnancy.

MAIN RESULTS

The developed algorithm improves the reliable automatic detection of fetal body movements independent of the fetal sleep states and their changes in the individual MCG recordings. In the fetuses aged 34-38 WGA 94% of 15  ×  15 HR accelerations were coupled with detected movements. The visual inspection of the movement graphs of 30 fetuses aged 20-32 WGA supports the transferability of the movement detector to this age. In four subjects MCG-based movement detection and maternal report on percepted fetal movements were consistent.

SIGNIFICANCE

The presented methodology allows the parallel automatic acquisition of precise fetal heart rate variability (HRV) indices based on subsequent beat intervals and of fetal body movements from MCG recordings during late 2nd and 3rd trimester. Potential advantages of parallel monitoring of fetal HRV and movements using MCG compared to established ultrasound technology should be investigated in subsequent studies with respect to the identification of fetuses at risk.

Effects of lighting schedule during incubation of broiler chicken embryos on leg bone development at hatch and related physiological characteristics

Providing a broiler chicken embryo with a lighting schedule during incubation may stimulate leg bone development. Bone development may be stimulated through melatonin, a hormone released in darkness that stimulates bone development, or increased activity in embryos exposed to a light-dark rhythm. Aim was to investigate lighting conditions during incubation and leg bone development in broiler embryos, and to reveal the involved mechanisms. Embryos were incubated under continuous cool white 500 lux LED light (24L), continuous darkness (24D), or 16h of light, followed by 8h of darkness (16L:8D) from the start of incubation until hatching. Embryonic bone development largely takes place through cartilage formation (of which collagen is an important component) and ossification. Expression of genes involved in cartilage formation (col1α2, col2α1, and col10α1) and ossification (spp1, sparc, bglap, and alpl) in the tibia on embryonic day (ED)13, ED17, and at hatching were measured through qPCR. Femur and tibia dimensions were determined at hatch. Plasma growth hormone and corticosterone and pineal melatonin concentrations were determined every 4h between ED18.75 and ED19.5. Embryonic heart rate was measured twice daily from ED12 till ED19 as a reflection of activity. No difference between lighting treatments on gene expression was found. 24D resulted in higher femur length and higher femur and tibia weight, width, and depth at hatch than 16L:8D. 24D furthermore resulted in higher femur length and width and tibia depth than 24L. Embryonic heart rate was higher for 24D and 16L:8D in both its light and dark period than for 24L, suggesting that 24L embryos may have been less active. Melatonin and growth hormone showed different release patterns between treatments, but the biological significance was hard to interpret. To conclude, 24D resulted in larger leg bones at hatch than light during incubation, but the underlying pathways were not clear from present data.

Multiscale Coupling of Uterine Electromyography and Fetal Heart Rate as a Novel Indicator of Fetal Neural Development

Fetal nerve maturation is a dynamic process, which is reflected in fetal movement and fetal heart rate (FHR) patterns. Classical FHR variability (fHRV) indices cannot fully reflect their complex interrelationship. This study aims to provide an alternative insight for fetal neural development by using the coupling analysis of uterine electromyography (UEMG) and FHR acceleration. We investigated 39 normal pregnancies with appropriate for gestational age (AGA) and 19 high-risk pregnancies with small for gestational age (SGA) at 28-39 weeks. The UEMG and FHR were recorded simultaneously by a trans-abdominal device during the night (10 p.m.-8 a.m.). Cross-wavelet analysis was used to characterize the dynamic relationship between FHR and UEMG. Subsequently, a UEMG-FHR coupling index (UFCI) was extracted from the multiscale coupling power spectrum. We examined the gestational-age dependency of UFCI by linear/quadratic regression models, and the ability to screen for SGA using binary logistic regression. Also, the performances of classical fHRV indices, including short-term variation (STV), averaged acceleration capacity (AAC), and averaged deceleration capacity (ADC), time- and frequency- domain indices, and multiscale entropy (MSE), were compared as references on the same recordings. The results showed that UFCI provided a stronger age predicting value with R² = 0.480, in contrast to the best value among other fHRV indices with R² = 0.335, by univariate regression models. Also, UFCI achieved superior performance for predicting SGA with the area under the curve (AUC) of 0.88, compared with 0.79 for best performance of other fHRV indices. The present results indicate that UFCI provides new information for early detection and comprehensive interpretation of intrauterine growth restriction in prenatal diagnosis, and helps improve the screening of SGA.

Fetal heart rate, heart rate variability, and heart rate/movement coupling in the Safe Passage Study

OBJECTIVE

To determine normative values for heart rate patterns in healthy fetuses.

METHODS

This research is from the Safe Passage Study conducted by the Prenatal Alcohol and SIDS and Stillbirth (PASS) Network. A standardized protocol assessed fetal heart rate (FHR), heart rate variability (HRV), and movement from 1655 fetuses at three-time points during gestation (20-24 weeks, 28-32 weeks, 34-38 weeks gestation).

RESULTS

FHR decreased while HRV increased over gestation. At the latter two ages, males had significantly lower FHR than females while there were no sex differences in FHR at 20-24 weeks. When accounting for the fetal state during late gestation (34-28 weeks), we found that males had significantly lower FHR than females in the active fetal state only.

CONCLUSION

Results demonstrate significant state, gestational age, and sex-related changes in cardiac activity, somatic activity, and autonomic function as the fetus approaches birth.

Major depressive disorder during pregnancy: Psychiatric medications have minimal effects on the fetus and infant yet development is compromised

Psychotropic medication use and psychiatric symptoms during pregnancy each are associated with adverse neurodevelopmental outcomes in offspring. Commonly, studies considering medication effects do not adequately assess symptoms, nor evaluate children when the effects are believed to occur, the fetal period. This study examined maternal serotonin reuptake inhibitor and polypharmacy use in relation to serial assessments of five indices of fetal neurobehavior and Bayley Scales of Infant Development at 12 months in N = 161 socioeconomically advantaged, non-Hispanic White women with a shared risk phenotype, diagnosed major depressive disorder. On average fetuses showed the expected development over gestation. In contrast, infant average Bayley psychomotor and mental development scores were low (M = 84.10 and M = 89.92, range of normal limits 85-114) with rates of delay more than 2-3 times what would be expected based on this measure's normative data. Controlling for prenatal and postnatal depressive symptoms, prenatal medication effects on neurobehavioral development were largely undetected in the fetus and infant. Mental health care directed primarily at symptoms may not address the additional psychosocial needs of women parenting infants. Speculatively, prenatal serotonin reuptake inhibitor exposure may act as a plasticity rather than risk factor, potentially enhancing receptivity to a nonoptimal postnatal environment in some mother-infant dyads.

The relation of fetal colon and rectum diameters with labor in healthy late-third trimester pregnancies

OBJECTIVE

To investigate the associations of fetal colon-rectum diameters with labor and fetal distress or meconium passage in healthy pregnancies in the late 3rd trimester.

STUDY DESIGN

A total of 162 healthy, singleton pregnant women at ≥36^0/7 weeks who were in the latent-phase of labor (n = 69) or those not in labor (n = 93, controls) at the time of ultrasound examination were enrolled. Fetal colon (ascending, transverse, descending, sigmoid) and rectum diameters, Doppler indices of materno-fetal vessels were measured. Data were analyzed according to the mode of delivery.

RESULTS

Fetal colon-rectum diameters were smaller in women in labor compared to controls (p = 0.001). Positive correlations were observed between fetal colon-rectum diameters and interval between ultrasound and labor onset in the control group except for those who had scheduled cesarean sections (C/S) (p = 0.001). Similar colon-rectum measurements were obtained in fetuses delivered via cesarean section due to fetal distress or to other indications (p > 0.05). In women who had uterine contractions during ultrasound examination; later delivered by vaginal route, no association was observed between Apgar scores and colon-rectum diameters during latent-phase (p > 0.05), and also there were significant positive correlations between different segments of colon-rectum diameters and duration of neonatal meconium passage (p < 0.05).

CONCLUSION

Fetal colon and rectum diameters are smaller during labor and the measurements tend to diminish as the labor approaches, but do not indicate fetal distress.

Maternal salivary testosterone in pregnancy and fetal neuromaturation

Testosterone exposure during pregnancy has been hypothesized as a mechanism for sex differences in brain and behavioral development observed in the postnatal period. The current study documents the natural history of maternal salivary testosterone from 18 weeks gestation of pregnancy to 6 months postpartum, and investigates associations with fetal heart rate, motor activity, and their integration. Findings indicate maternal salivary testosterone increases with advancing gestation though no differences by fetal sex were detected. High intra-individual stability in prenatal testosterone levels extend into the postnatal period, particularly for pregnancies with male fetuses. With respect to fetal development, by 36 weeks gestation higher maternal prenatal salivary testosterone was significantly associated with faster fetal heart rate and less optimal somatic-cardiac integration. Measurement of testosterone in saliva is a useful tool for repeated-measures studies of hormonal concomitants of pregnancy. Moreover, higher maternal testosterone levels are associated with modest interference to fetal neurobehavioral development.

Validating a Noninvasive Technique for Monitoring Embryo Movement In Ovo

Avian embryos are a commonly used model system for developmental studies, but monitoring of physiological parameters such as heart rate (HR) and movement in ovo poses a challenge to researchers. These are also increasingly common research objectives for ecological and embryo behavior studies in oviparous species. We therefore explored the validity of a new digital egg-monitoring system for the noninvasive monitoring of these parameters. We tested the relationship between frequency-of-movement values gathered by digital monitoring and those gathered by the current standard method, which is comparatively invasive and requires egg windowing, and demonstrated that the digital monitoring method effectively distinguishes individual movements but cannot reliably monitor HR in actively motile embryos. We therefore provide recommendations for the appropriate use of this technique for avian physiologists. We also applied the digital monitoring method to reveal how frequency of movement varies throughout prenatal ontogeny in the chicken and showed that commonly used protocols in developmental studies can themselves alter motility; egg windowing and application of light modulate frequency of movement. Recent work has revealed the importance of embryo motility in regulating gene expression and cellular activity during developmental processes. Together with our data, this highlights the value of noninvasive monitoring methods and the importance of controlling for altered embryo motility/behavior in developmental studies.

A computer-aided approach to detect the fetal behavioral states using multi-sensor Magnetocardiographic recordings

We propose a novel computational approach to automatically identify the fetal heart rate patterns (fHRPs), which are reflective of sleep/awake states. By combining these patterns with presence or absence of movements, a fetal behavioral state (fBS) was determined. The expert scores were used as the gold standard and objective thresholds for the detection procedure were obtained using Receiver Operating Characteristics (ROC) analysis. To assess the performance, intraclass correlation was computed between the proposed approach and the mutually agreed expert scores. The detected fHRPs were then associated to their corresponding fBS based on the fetal movement obtained from fetal magnetocardiogaphic (fMCG) signals. This approach may aid clinicians in objectively assessing the fBS and monitoring fetal wellbeing.

Fetal heart rate and motor development in overweight and obese pregnant women

OBJECTIVE

To determine the relationship between maternal prepregnancy body mass index (BMI) and fetal cardiac and motor activity and integration during the second half of pregnancy.

METHODS

Longitudinal data were collected from 610 nonsmoking women with normally progressing pregnancies at three gestational periods (24, 30-32, and 36 weeks) across eight cohorts studied between 1997 and 2013. Fifty minutes of fetal heart rate and motor activity data were collected at each period via actocardiography in a laboratory setting. Data were digitized and analyzed using customized software. Standard BMI categories were computed from maternal prepregnancy weight and height. Participants were stratified into normal weight (n=401, 65.7%), overweight (n=137, 22.5%), or obese (n=72, 11.8%).

RESULTS

Fetuses of obese women showed lower heart rate variability and fewer accelerations relative to fetuses of normal weight women. Fetuses of both obese and overweight women exhibited more vigorous motor activity than fetuses of normal weight women. Cardiac-somatic integration was reduced in both obese and overweight groups. Findings differed by gestational age at assessment.

CONCLUSIONS

Excess maternal prepregnancy weight in overweight and obese women alters the normal trajectory of fetal cardiac and motor development and their integration, with effects amplified as pregnancy progresses.

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

The gestational foundation of sex differences in development and vulnerability

Despite long-standing interest in the role of sex on human development, the functional consequences of fetal sex on early development are not well-understood. Here we explore the gestational origins of sex as a moderator of development. In accordance with the focus of this special issue, we examine evidence for a sex differential in vulnerability to prenatal and perinatal risks. Exposures evaluated include those present in the external environment (e.g., lead, pesticides), those introduced by maternal behaviors (e.g., alcohol, opioid use), and those resulting from an adverse intrauterine environment (e.g., preterm birth). We also provide current knowledge on the degree to which sex differences in fetal neurobehavioral development (i.e., cardiac and motor patterns) are present prior to birth. Also considered are contemporaneous and persistent sex of fetus effects on the pregnant woman. Converging evidence confirms that infant and early childhood developmental outcomes of male fetuses exposed to prenatal and perinatal adversities are more highly impaired than those of female fetuses. In certain circumstances, male fetuses are both more frequently exposed to early adversities and more affected by them when exposed than are female fetuses. The mechanisms through which biological sex imparts vulnerability or protection on the developing nervous system are largely unknown. We consider models that implicate variation in maturation, placental functioning, and the neuroendocrine milieu as potential contributors. Many studies use sex as a control variable, some analyze and report main effects for sex, but those that report interaction terms for sex are scarce. As a result, the true scope of sex differences in vulnerability is unknown.

Pregnancy distress gets under fetal skin: Maternal ambulatory assessment & sex differences in prenatal development

Prenatal maternal distress is associated with an at-risk developmental profile, yet there is little fetal evidence of this putative in utero process. Moreover, the biological transmission for these maternal effects remains uncertain. In a study of n = 125 pregnant adolescents (ages 14-19), ambulatory assessments of daily negative mood (anger, frustration, irritation, stress), physical activity, blood pressure, heart rate (every 30 min over 24 hr), and salivary cortisol (six samples) were collected at 13-16, 24-27, 34-37 gestational weeks. Corticotropin-releasing hormone, C-reactive protein, and interleukin 6 from blood draws and 20 min assessments of fetal heart rate (FHR) and movement were acquired at the latter two sessions. On average, fetuses showed development in the expected direction (decrease in FHR, increase in SD of FHR and in the correlation of movement and FHR ("coupling")). Maternal distress characteristics were associated with variations in the level and trajectory of fetal measures, and results often differed by sex. For males, greater maternal 1st and 2nd session negative mood and 2nd session physical activity were associated with lower overall FHR (p < .01), while 1st session cortisol was associated with a smaller increase in coupling (p < .01), and overall higher levels (p = .05)-findings suggesting accelerated development. For females, negative mood, cortisol, and diastolic blood pressure were associated with indications of relatively less advanced and accelerated outcomes. There were no associations between negative mood and biological variables. These data indicate that maternal psychobiological status influences fetal development, with females possibly more variously responsive to different exposures.

Developing fetal motor-cardiovascular coordination analyzed from multi-channel magnetocardiography

Fetal movements (FM) related heart rate accelerations (AC) are an important maturation criterion. Since Doppler-based time resolution is not sufficient for accompanying heart rate variability analysis, the work is aimed at a comprehensive FM-AC analysis using magnetocardiographic recordings from fetuses during sleep.We identify FM and AC by independent component analysis and automatic recognition algorithms. We investigate associations between FM and AC of different magnitude by means of event coincidence and time series cross-correlation over the maturation period of 21-40 weeks of gestation (WGA).FM related AC appear with increasing AC magnitude and WGA. Vice versa, AC related FM appear independent of WGA, but more frequently with increasing AC amplitude. The FM-AC correlation exists already at 21 WGA and further increases with WGA while the variability of its time delay decreases. Hence, FM and AC are clearly associated over the whole investigated maturation period. The increase of FM related AC runs parallel to the increasing AC magnitude.The MCG methodology was confirmed and results from previous Doppler-based analyses reproduced. Hence, MCG recordings allow the collective analysis of heart rate variability based maturation indices and FM related AC. This synergism may improve the diagnosis of fetal developmental disorders.

Sex-specific impact of maternal-fetal risk factors on depression and cardiovascular risk 40 years later

Major depressive disorder (MDD) and cardiovascular disease (CVD) represent leading causes of morbidity and mortality worldwide. We tested the hypothesis that growth restriction and preeclampsia (referred to as fetal risk) are significant predictors of these conditions, with women at higher risk in adulthood. Adult offspring exposed to fetal risk factors and their discordant siblings were from two prenatal cohorts, whose mothers were followed through pregnancy and whom we recruited as adults 40 years later (n = 538; 250 males and 288 females). Subjects were psychiatrically diagnosed and underwent a stress challenge during which parasympathetic regulation was assessed by electrocardiogram, operationalized as high-frequency R-R interval variability (HF-RRV). Linear mixed models and generalized estimating equations were used to examine the relationship of fetal risk on HF-RRV, MDD and comorbidity of low HF-RRV (lowest 25th percentile) and MDD, including interactions with sex and socioeconomic status (SES). Fetal risk was significantly associated with low HF-RRV response (F = 3.64, P = 0.05), particularly among low SES (interaction: F = 4.31, P < 0.04). When stratified by MDD, the fetal risk impact was three times greater among MDD compared with non-MDD subjects (effect size: 0.21 v. 0.06). Females had a significantly higher risk for the comorbidity of MDD and low HF-RRV than males (relative risk (RR) = 1.36, 95% CI: 1.07-1.73), an association only seen among those exposed to fetal risk (RR = 1.38, 95% CI: 1.04-1.83). Findings suggest that these are shared fetal antecedents to the comorbidity of MDD and CVD risk 40 years later, an association stronger in females than in males.

Assessment of coupling between trans-abdominally acquired fetal ECG and uterine activity by bivariate phase-rectified signal averaging analysis

Couplings between uterine contractions (UC) and fetal heart rate (fHR) provide important information on fetal condition during labor. At present, couplings between UC and fHR are assessed by visual analysis and interpretation of cardiotocography. The application of computerized approaches is restricted due to the non-stationarity of the signal, missing data and noise, typical for fHR. Herein, we propose a novel approach to assess couplings between UC and fHR, based on a signal-processing algorithm termed bivariate phase-rectified signal averaging (BPRSA).

Methods

Electrohysterogram (EHG) and fetal electrocardiogram (fECG) were recorded non-invasively by a trans-abdominal device in 73 women at term with uneventful singleton pregnancy during the first stage of labor. Coupling between UC and fHR was analyzed by BPRSA and by conventional cross power spectral density analysis (CPSD). For both methods, degree of coupling was assessed by the maximum coefficient of coherence (C_PRSA and C_RAW, respectively) in the UC frequency domain. Coherence values greater than 0.50 were consider significant. C_PRSA and C_RAW were compared by Wilcoxon test.

Results

At visual inspection BPRSA analysis identified coupled periodicities in 86.3% (63/73) of the cases. 11/73 (15%) cases were excluded from further analysis because no 30 minutes of fECG recording without signal loss was available for spectral analysis. Significant coupling was found in 90.3% (56/62) of the cases analyzed by BPRSA, and in 24.2% (15/62) of the cases analyzed by CPSD, respectively. The difference between median value of C_PRSA and C_RAW was highly significant (0.79 [IQR 0.69–0.90] and 0.29 [IQR 0.17–0.47], respectively; p<0.0001).

Conclusion

BPRSA is a novel computer-based approach that can be reliably applied to trans-abdominally acquired EHG-fECG. It allows the assessment of correlations between UC and fHR patterns in the majority of labors, overcoming the limitations of non-stationarity and artifacts. Compared to standard techniques of cross-correlations, such as CPSD, BPRSA is significantly superior.

Dynamics of the formation of rhythmic activity of the heart in fetuses and newborn rats

The development of heart activity and its relationship with respiratory and motor activities were studied in rat fetuses with preserved placental circulation on gestation days 15-20 (E15-20) and in newborn rats (P0). During the studied period, the heart rate in fetuses increased from 175.93±6.10 bpm (E15) to 271.82±5.93 bpm (E20). After birth, the heart rate decreased to 220.94±8.73 bpm. Heart rate variability in the decasecond and near-minute ranges was detected. At E16 stage it is presented by slow regular oscillations lasting for 20-35 sec with an amplitude of 10-45 msec. Comparison of functional activities of the cardiac and somatic motor systems showed that at E16, fluctuations in heart rate are independent of the bouts of motor excitation. During growing, the degree of synchronization of heart rate variability with physical activity increased. E17-18 stage is characterized by short-term episodes of heart rate deceleration associated with motor activity; their duration and amplitude did not depend much on the force of movement. At E19-20, decelerations typical of early gestation terms were replaced by acceleration-type reactions typical for mature organism, which is related to maturation of coordination function of the nervous system. In the heart rhythm, respiratory arrhythmia appears during episodes of rhythmic breathing. Newborn rats demonstrated acceleration episodes; their parameters depend on the force of motor bouts; respiratory arrhythmia was not observed.

Pregnancies exposed to methadone, methadone and other illicit substances, and poly-drugs without methadone: a comparison of fetal neurobehaviors and infant outcomes

BACKGROUND

It is suspected that there is a continuum of impairment among prenatally drug-exposed infants, such that opioid and/or poly-drug exposure confers the highest risk for adverse neonatal outcomes than other classes of substances or single substance exposures. Suitable control groups are difficult to identify. This study compared fetal neurobehavioral development and infant outcomes in offspring of three groups of pregnant women in drug treatment. Exposure groups include: Methadone+other illicit substances (MM+Poly) and two groups currently abstinent for poly drug exposures: Methadone only (MM/A) and Non-Methadone (NM/A).

METHODS

Forty-nine women (19 MM+Poly, 18 MM/A, and 12 NM/A) underwent fetal monitoring at 36 weeks gestation at peak and trough levels of methadone (MM+Poly; MM/A) or at comparable morning and afternoon times (NM/A). Fetal heart rate (FHR), heart rate variability (FHRV) and motor activity (FM) data were collected. Infant measures included birth outcomes and Neonatal Abstinence Syndrome (NAS) assessment.

RESULTS

As compared to the NM/A group, cardiac measures were decreased in methadone-exposed fetuses at peak levels. FHR was significantly more suppressed in the MM+Poly group. FM was significantly lower in the MM/A vs. the NM/A group at both peak and trough, indicative of more persistent exposure effects. The MM+Poly group delivered 1 week earlier and required NAS pharmacological treatment twice as often as the MM/A group.

CONCLUSIONS

Results support the notion that poly-drug exposure may potentiate the effects of methadone on the fetus and infant and highlights the need for intensified treatment for methadone-maintained women who abuse other substances.

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.

A novel approach to track fetal movement using multi-sensor magnetocardiographic recordings

Changes in fetal magnetocardiographic (fMCG) signals are indicators for fetal body movement. We propose a novel approach to reliably extract fetal body movements based on the field strength of the fMCG signal independent of its frequency. After attenuating the maternal MCG, we use a Hilbert transform approach to identify the R-wave. At each R-wave, we compute the center-of-gravity (cog) of the coordinate positions of MCG sensors, each weighted by the magnitude of the R-wave amplitude recorded at the corresponding sensor. We then define actogram as the distance between the cog computed at each R-wave and the average of the cog from all the R-waves in a 3-min duration. By applying a linear de-trending approach to the actogram we identify the fetal body movement and compare this with the synchronous occurrence of the acceleration in the fetal heart rate. Finally, we apply this approach to the fMCG recorded simultaneously with ultrasound from a single subject and show its improved performance over the QRS-amplitude based approach in the visually verified movements. This technique could be applied to transform the detection of fetal body movement into an objective measure of fetal health and enhance the predictive value of prevalent clinical testing for fetal wellbeing.

Fetal neurobehavioral effects of exposure to methadone or buprenorphine

As part of a double-blind study of medication treatment for opioid dependence during pregnancy, 17 opioid-dependent pregnant women maintained on either buprenorphine or methadone underwent fetal monitoring at 24, 28, 32, and 36 weeks gestation. Maternal demographic information and infant outcomes did not significantly differ by medication group. Earlier in gestation (24 and 28 weeks), buprenorphine-exposed fetuses had higher levels of fetal heart rate variability, more accelerations in fetal heart rate and greater coupling between fetal heart rate and fetal movement than the methadone-exposed group (all ps < .05). Later in gestation (32 and 36 weeks), buprenorphine-exposed fetuses displayed less suppression of motor activity and longer duration of movements than the methadone-exposed group (all ps < .05). These results may have implications for the optimal treatment of the opioid-dependent pregnant woman.

Evaluation of normal neurological development of human fetuses from 21 to 30 weeks' gestation through fetal auditory evoked response

OBJECTIVES

To evaluate the neurological maturation of fetuses between 21 and 30 weeks' gestation by the auditory evoked response.

METHODS

The auditory evoked responses of 25 normal singleton fetuses were observed once a week from 21 to 30 weeks' gestation. The stimulus consisted of five pulses of sinusoidal waves, for 2 s, at 1500 cycles/s, with a sound pressure of 125 dB.

RESULTS

Fetal auditory evoked response increased with neurological maturation, presenting two main points of positive discontinuity. The two points in the heart response were detected between the 24(th)/25(th) and the 27(th)/28(th) week. From the 27(th) week on, fetal motor response (FMR) was always present. Initial fetal heart response presented a fluctuation pattern between the 21(st) and the 30(th) week, with a tendency to increase as gestational age advanced. Fetal heart response also increased with gestational age. Late response (LR) fluctuated until the 29(th) week, and was always present after that period.

CONCLUSIONS

The maturation of the fetal nervous system is clearly demonstrated by changes in the auditory evoked responses in different gestational ages, and presents some discontinuity points.

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.

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.

Prenatal development of intrafetal and maternal-fetal synchrony

Fetal and maternal data were monitored serially at 6 gestational ages from 20 to 38 weeks in 195 Peruvian fetuses. Digitized data included fetal heart rate and motor activity, as well as maternal heart rate and electrodermal conductance. Time series analysis evaluated the development of synchrony in 2 streams of fetal functioning and between mothers and fetuses. Intrafetal synchrony between heart rate and motor activity developed in an orderly fashion, with peak cross-correlation approaching an asymptote at 5 s at 28 weeks. Synchrony was not observed between fetal heart rate and maternal measures. Fetal motor activity exhibited synchrony with both maternal electrodermal and heart rate activity. Implications for revealing fundamental properties of neural development prior to birth are discussed.

Antenatal testing-a reevaluation: executive summary of a Eunice Kennedy Shriver National Institute of Child Health and Human Development workshop

In August 2007, the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the National Institutes of Health Office of Rare Diseases, the American College of Obstetricians and Gynecologists, and the American Academy of Pediatrics cosponsored a 2-day workshop to reassess the body of evidence supporting antepartum assessment of fetal well-being, identify key gaps in the evidence, and formulate recommendations for further research. Participants included experts in obstetrics and fetal physiology and representatives from relevant stakeholder groups and organizations. This article is a summary of the discussions at the workshop, including synopses of oral presentations on the epidemiology of stillbirth and fetal neurological injury, fetal physiology, techniques for antenatal monitoring, and maternal and fetal indications for monitoring. Finally, a synthesis of recommendations for further research compiled from three breakout workgroups is presented.

Sleep fragmentation and evidence for sleep debt in alcohol-exposed infants

BACKGROUND

Infants exposed prenatally to alcohol are at increased risk for poor neurodevelopmental outcome including Sudden Infant Death Syndrome.

AIM

To examine the relationship between prenatal alcohol exposure, sleep, arousal and sleep-related spontaneous motor movements in early infancy.

STUDY DESIGN

Low-income women (N=13) were interviewed regarding pre- and pregnancy rates of alcohol, cigarette smoking and other substance use in the perinatal period. Infants were examined in a laboratory nap study using EEG, videography and actigraphy at 6-8 weeks of age. Estimates of maternal pre- and pregnancy alcohol use were used to divide infants into high vs. low maternal alcohol use groups.

SUBJECTS

Mother-infant dyads recruited from a family practice clinic.

OUTCOME MEASURES

Sleep-related spontaneous movements, behavioral state, and maternal assessments of infant alertness and irritability.

RESULTS

Pre-pregnancy rates of alcohol consumption including binge drinking correlated with maternal report of poor infant alertness, and increased irritability. High maternal exposure groups showed increased sleep fragmentation, e.g., frequency and duration of wakefulness following sleep onset and decreased active sleep. Bout analysis of the temporal structure of sleep-related spontaneous movements showed significantly reduced bout duration associated with high maternal alcohol use.

CONCLUSION

These results present evidence that prenatal alcohol exposure disrupts postnatal sleep organization and suppresses spontaneous movements during sleep, and increased sleep fragmentation promotes sleep deprivation. Results are consistent with the SIDS model of chronic sleep debt and suggest that attenuated sleep-related movements should be examined as an important modulator of cardiorespiratory functions during sleep in high-risk groups.

Docosahexaenoic acid and cognitive function: Is the link mediated by the autonomic nervous system?

Docosahexaenoic acid is a long-chain polyunsaturated fatty acid that is found in large quantity in the brain and which has repeatedly been observed to be related in positive ways to both cognitive function and cardiovascular health. The mechanisms through which docosahexaenoic acid affects cognition are not well understood, but in this article, we propose a hypothesis that integrates the positive effects of docosahexaenoic acid in the cognitive and cardiovascular realms through the autonomic nervous system. The autonomic nervous system is known to regulate vital functions such as heart rate and respiration, and has also been linked to basic cognitive components related to arousal and attention. We review the literature from this perspective, and delineate the predictions generated by the hypothesis. In addition, we provide new data showing a link between docosahexaenoic acid and fetal heart rate that is consistent with the hypothesis.

Ontogeny of EEG-sleep from neonatal through infancy periods

Serial neonatal and infant electroencephalographic (EEG)-polysomnographic studies document the ontogeny of cerebral and noncerebral physiologic behaviors based on visual inspection or computer analyses. EEG patterns and their relationship to other physiologic signals serve as templates for normal brain organization and maturation, subserving multiple interconnected neuronal networks. Interpretation of serial EEG-sleep patterns also helps track the continuity of brain functions from intrauterine to extrauterine time periods. Recognition of the ontogeny of behavioral and electrographic patterns provides insight into the developmental neurophysiological expression of neural plasticity. Sleep ontogenesis from neonatal and infancy periods documents expected patterns of postnatal brain maturation, which allows for alterations from genetically programmed neuronal processes under stressful and/or pathological conditions. Automated analyses of cerebral and noncerebral signals provide time- and frequency-dependent computational phenotypes of brain organization and maturation in healthy or diseased states. Research pertaining to the developmental origins of health and disease can use these computational phenotypes to design longitudinal studies for the assessment of gene-environment interactions. Computational strategies may ultimately improve our diagnostic skills to identify special-needs children and to track the neurorehabilitative care of the high-risk fetus, neonate, and infant.

Fetal heart rate and variability: stability and prediction to developmental outcomes in early childhood

Stability in cardiac indicators before birth and their utility in predicting variation in postnatal development were examined. Fetal heart rate and variability were measured longitudinally from 20 through 38 weeks gestation (n = 137) and again at age 2 (n = 79). Significant within-individual stability during the prenatal period and into childhood was demonstrated. Fetal heart rate variability at or after 28 weeks gestation and steeper developmental trajectories were significantly associated with mental and psychomotor development at 2 years (n = 82) and language ability at 2.5 years (n = 61). These data suggest that the foundations of individual differences in autonomic control originate during gestation and the developmental momentum of the fetal period continues after birth.

On time series analysis of public health and biomedical data

This paper gives an overview of time series ideas and methods used in public health and biomedical research. A time series is a sequence of observations made over time. Examples in public health include daily ozone concentrations, weekly admissions to an emergency department, or annual expenditures on health care in the United States. Time series models are most commonly used in regression analysis to describe the dependence of the response at each time on predictor variables including covariates and possibly previous values in the series. For example, Bell et al. ( 2 ) use time series methods to regress daily mortality in U.S. cities on concentrations of particulate air pollution. Time series methods are necessary to make valid inferences from data by accounting for the correlation among repeated responses over time.

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.

The psychophysiology of the maternal-fetal relationship

The enigmatic quality of the maternal-fetal relationship has been extolled throughout history with little empirical support. We apply time series analysis to data for 137 maternal-fetal pairs collected at 20, 24, 28, 32, 36, and 38 weeks gestation. Maternal heart rate and skin conductance data were digitized in tandem with fetal heart rate and motor activity. No temporal relations between fetal heart rate and either maternal variable were found, although averaged maternal and fetal heart rates were correlated from 32 weeks. Consistent temporal associations between fetal movement and maternal heart rate and skin conductance were detected. Fetal movement stimulated rises in each parameter, peaking at 2 and 3 s, respectively. Associations did not change over gestation, were unaffected by a maternal stressor, and showed within-pair stability. The bidirectional nature of the maternal-fetal relationship is considered.

Fetal Neurobehavioral Development: A Tale of Two Cities

Longitudinal neurobehavioral development was examined in 237 fetuses of low-risk pregnancies from 2 distinct populations--Baltimore, Maryland, and Lima. Peru--at 20, 24, 28, 32, 36, and 38 weeks gestation. Data were based on digitized Doppler-based fetal heart rate (FHR) and fetal movement (FM). In both groups. FHR declined while variability, episodic accelerations, and FM-FHR coupling increased, with discontinuities evident between 28 and 32 weeks gestation. Fetuses in Lima had higher FHR and lower variability, accelerations, and FM-FHR coupling. Declines in trajectories were typically observed 1 month sooner in Lima, which magnified these disparities. Motor activity differences were less consistent. No sex differences in fetal neurobehaviors were detected. It is concluded that population factors can influence the developmental niche of the fetus.