Foetal heart rate and maternal emotional state

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.

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

Physiological reactivity of pregnant women to evoked fetal startle

OBJECTIVE

The bidirectional nature of mother-child interaction is widely acknowledged during infancy and childhood. Prevailing models during pregnancy focus on unidirectional influences exerted by the pregnant woman on the developing fetus. Prior work has indicated that the fetus also affects the pregnant woman. Our objective was to determine whether a maternal psychophysiological response to stimulation of the fetus could be isolated.

METHODS

Using a longitudinal design, an airborne auditory stimulus was used to elicit a fetal heart rate and motor response at 24 (n=47) and 36 weeks (n=45) of gestation. Women were blind to condition (stimulus versus sham). Maternal parameters included cardiac (heart rate) and electrodermal (skin conductance) responses. Multilevel modeling of repeated measures with 5 data points per second was used to examine fetal and maternal responses.

RESULTS

As expected, compared to a sham condition, the stimulus generated a fetal motor response at both gestational ages, consistent with a mild fetal startle. Fetal stimulation was associated with significant, transient slowing of maternal heart rate coupled with increased skin conductance within 10s of the stimulus at both gestational ages. Nulliparous women showed greater electrodermal responsiveness. The magnitude of the fetal motor response significantly corresponded to the maternal skin conductance response at 5, 10, 15, and 30s following stimulation.

CONCLUSION

Elicited fetal movement exerts an independent influence on the maternal autonomic nervous system. This finding contributes to current models of the dyadic relationship during pregnancy between fetus and pregnant woman.

Fetal serotonin signaling: setting pathways for early childhood development and behavior

Finely tuning levels of the key neurotransmitter serotonin (5-hydroxytryptamine [5-HT]) during early life is essential for brain development and setting pathways for health and disorder across the early life span. Given the central role of 5-HT in brain development, regulation of mood, stress reactivity, and risk for psychiatric disorders, alterations in 5-HT signaling early in life have critical implications for behavior and mental health in childhood and adolescence. This article reviews the developmental consequences of two key influences that alter fetal 5-HT signaling: (1) in utero exposure to 5-HT reuptake inhibitor antidepressants, and (2) genetic variations in the 5-HT transporter gene (SLC6A4). The consequences of altered prenatal 5-HT signaling vary greatly, and developmental outcomes depend on an ongoing interplay between biological (genetic/epigenetic variations), experiential (prenatal drug or maternal mood exposure), and contextual (postnatal social environment) variables. Emerging evidence suggests both exposure to 5-HT reuptake inhibitors and genetic variations that affect 5-HT signaling may increase sensitivity to negative social contexts for some individuals, whereas for others, they may confer sensitivity to positive life circumstances. In this sense, factors that change central 5-HT levels may function less like influences that predict "vulnerability," but rather act like "plasticity factors." Understanding the impact of early changes in serotonergic programming offers critical insights that might explain patterns of individual differences in developmental risk and resilience.

Exposure to prenatal psychobiological stress exerts programming influences on the mother and her fetus

BACKGROUND/AIMS

Accumulating evidence from a relatively small number of prospective studies indicates that exposure to prenatal stress profoundly influences the developing human fetus with consequences that persist into childhood and very likely forever.

METHODS

Maternal/fetal dyads are assessed at ∼20, ∼25, ∼31 and ∼36 weeks of gestation. Infant assessments begin 24 h after delivery with the collection of cortisol and behavioral responses to the painful stress of the heel-stick procedure and measures of neonatal neuromuscular maturity. Infant cognitive, neuromotor development, stress and emotional regulation are evaluated at 3, 6 12 and 24 months of age. Maternal psychosocial stress and demographic information is collected in parallel with infant assessments. Child neurodevelopment is assessed with cognitive tests, measures of adjustment and brain imaging between 5 and 8 years of age.

RESULTS

Psychobiological markers of stress during pregnancy, especially early in gestation, result in delayed fetal maturation, disrupted emotional regulation and impaired cognitive performance during infancy and decreased brain volume in areas associated with learning and memory in 6- to 8-year-old children. We review findings from our projects that maternal endocrine alterations that accompany pregnancy and influence fetal/infant/child development are associated with decreased affective responses to stress, altered memory function and increased risk for postpartum depression.

CONCLUSIONS

Our findings indicate that the mother and her fetus both are influenced by exposure to psychosocial and biological stress. The findings that fetal and maternal programming occur in parallel may have important implications for long-term child development and mother/child interactions.

Gestational stress influences cognition and behavior

The developmental origins of disease or fetal programming model predicts that early exposures to threat or adverse conditions have lifelong consequences that result in harmful outcomes for health. The vast majority of the studies in support of the programming model in human beings are retrospective and most rely on surrogate measures of early experience such as birth weight or preterm birth. Recently, a small number of prospective studies have been reported that have documented the developmental consequences of exposures to stressful intrauterine conditions. These studies of gestational stress have clearly shown that fetal exposures to psychosocial and/or biological markers of adversity have significant and largely negative consequences for fetal, infant and child neurological development. Fetal exposure to stress, especially early in gestation, results in delayed fetal maturation and impaired cognitive performance during infancy and results in decreased brain volume in areas associated with learning and memory in children. The accumulating evidence supports the conclusion that fetal exposure to stress profoundly influences the nervous system, with consequences that persist into childhood and perhaps beyond.

Psychological and psychophysiological considerations regarding the maternal-fetal relationship

The earliest relationship does not begin with birth. Pregnant women construct mental representations of the fetus, and feelings of affiliation or "maternal-fetal attachment" generally increase over the course of gestation. While there is a fairly substantial literature on the development and moderation of psychological features of the maternal-fetal relationship, including the role of ultrasound imaging, relatively little is known about the manner in which maternal psychological functioning influences the fetus. Dispositional levels of maternal stress and anxiety are modestly associated with aspects of fetal heart rate and motor activity. Both induced maternal arousal and relaxation generate fairly immediate alterations to fetal neurobehaviors; the most consistently observed fetal response to changes in maternal psychological state involves suppression of motor activity. These effects may be mediated, in part, by an orienting response of the fetus to changes in the intrauterine environment. Conversely, there is evidence that fetal behaviors elicit maternal physiological responses. Integration of this finding into a more dynamic model of the maternal-fetal dyad, and implications for the postnatal relationship are discussed. Research on the period before birth affords tremendous opportunity for developmental scientists to advance understanding of the origins of human attachment.

Fetal responses to induced maternal relaxation during pregnancy

Fetal responses to induced maternal relaxation during the 32nd week of pregnancy were recorded in 100 maternal-fetal pairs using a digitized data collection system. The 18-min guided imagery relaxation manipulation generated significant changes in maternal heart rate, skin conductance, respiration period, and respiratory sinus arrhythmia. Significant alterations in fetal neurobehavior were observed, including decreased fetal heart rate (FHR), increased FHR variability, suppression of fetal motor activity (FM), and increased FM-FHR coupling. Attribution of the two fetal cardiac responses to the guided imagery procedure itself, as opposed to simple rest or recumbency, is tempered by the observed pattern of response. Evaluation of correspondence between changes within individual maternal-fetal pairs revealed significant associations between maternal autonomic measures and fetal cardiac patterns, lower umbilical and uterine artery resistance and increased FHR variability, and declining salivary cortisol and FM activity. Potential mechanisms that may mediate the observed results are discussed.

The dynamic placenta: II. Hypothetical model of a fetus driven transplacental water balance mechanism producing low apparent permeability in a highly permeable placenta

In vitro and isotopic studies in vivo have reported the paradox that the human placenta is highly permeable, water exchanging at 3.6 litres per hour at 35 weeks of gestation, but clinical measurements in vivo show net transfer is minimal, around 2 ml/day. Current theories are based on osmotic pressure balances, but changes in maternofetal hydrostatic pressure change much faster than osmotic factors could respond. An alternative explanation might be that net transfer is not in fact the result of passive mechanisms, but is actively controlled by the fetus itself. The fetus is well equipped to monitor changes in blood volume, such as via sensors in venous and atrial stretch receptors to control ANF and hence urine production. Transplacental water regulation requires modification of transvillus pressures. Placental sub-chorial arteries and veins (of extra-embryonic origin) have different sensitivities from fetal body tissues to some vasoactive substances, and stem villous veins have unusually well developed vascular smooth muscle. It is thus theoretically possible for the fetus to modify subchorial venous resistances, and hence villous capillary pressure with a suitable circulating placental venous constrictive agent. A computer modelling study was undertaken using a fictitious placental venous constricting agent "fictensin", considered to be released by the fetus in proportion to disturbance of vascular volume. The effective placental permeability fell in proportion to the tightness of this fetal control mechanism, suggesting that the apparent placental permeability measured in vivo is a measure of fetal control, not true permeability. However, the range of compensatory pressures that the fetus can produce by this means is limited and failure of such a mechanism could allow flooding or dehydration of the feto-placental unit. This may shed new light on disorders such as polyhydramnios and fetal hydrops.

Fetal response to induced maternal stress

BACKGROUND

Despite increased attention to the role of antenatal maternal psychological stress in postnatal development, remarkably little information is available on the nature of the intrauterine fetal response to maternal psychological state.

AIMS

To determine whether: (1) the fetus responds to maternal stress; (2) the fetal response changes over gestation; and (3) individual maternal and fetal response patterns are stable over time.

STUDY DESIGN

Induced maternal stress at 24 and 36 weeks gestational age using the Stroop color-word task.

SUBJECTS

137 low-risk pregnant women with normally developing fetuses.

OUTCOME MEASURES

Maternal (heart rate and skin conductance) and fetal (heart rate, heart rate variability, and motor activity) responses.

RESULTS

The manipulation evoked maternal sympathetic activation, which declined in magnitude from 24 to 36 weeks gestation. Fetuses responded to the manipulation with increased variability in heart rate (F(2,256)=7.80, p<0.001) and suppression of motor activity (F(2,216)=15.47, p<0.001). The magnitude of the fetal response increased over gestation. The degree of maternal reactivity to and recovery from the stressor were correlated over time (r's=0.53 and 0.60 for heart rate; r's=0.31 and 0.36 for skin conductance; p's<0.001). There was moderate stability in the magnitude of the fetal motor response (r=0.25, p<0.01).

CONCLUSIONS

Demonstration of fetal responses to maternal sympathetic activation evoked by a benign cognitive stressor suggests that fetal neurobehavioral regulation is routinely disrupted by maternal environmental intrusions. There is no evidence of a protective effect of diminished maternal sensitivity to stress on the fetus. Individual stability in the magnitude of the evoked maternal physiologic and psychological responses from 24 to 36 weeks and stability in the fetal motor response implies that characteristic response patterns emerge in utero. We propose that autonomic development is partially entrained through these processes.

The effects of maternal depression on fetal heart rate response to vibroacoustic stimulation

To better understand the effects of untreated maternal depression on the fetus, this study examined fetal heart rate (FHR) and FHR reactivity to vibroacoustic stimulation in pregnant women with untreated depression. The 20 participants were 32- to 36-week pregnant women divided into groups with depression (N = 10) and without depression (N = 10) based on the Beck Depression Inventory (BDI; Beck, 1977; Beck & Steer, 1987). Participants were attached to a fetal heart monitor, and 10 min of baseline FHR were recorded. A vibroacoustic stimulus (VAS) was presented, and an additional 10 min of FHR were recorded. Fetuses of mothers with depression had an elevated baseline FHR and a 3.5-fold delay in return to baseline FHR after VAS presentation. Additionally, mothers with depression had significantly higher anxiety levels and took fewer prenatal vitamins during pregnancy. Delayed habituation of FHR in the fetuses of mothers with depression may be due to alterations in the internal hormonal environment and could have implications for postnatal information processing.