Scherri B. Holland

Maternal Anxiety During Pregnancy: Effect on Fetal Behavior at 38 to 40 Weeks of Gestation

The purpose of this study was to determine if there is a relationship between fetal behavior and maternal anxiety during pregnancy. The study population consisted of 18 uncomplicated human pregnancies at 38 to 40 weeks gestation. Maternal anxiety was assessed one time using Spielbergers State-Trait Anxiety Inventory. After an overnight fast, each mother was given a standard meal on arrival to the fetal testing unit. Each fetus was examined for 4 hours using heart rate monitoring and real-time sonography. Fetal behavioral states were assigned based on heart rate pattern and the presence or absence of eye and gross body movements. We found that, compared with fetuses of mothers with low trait anxiety scores, fetuses of mothers with relatively high trait anxiety scores spent significantly more time in quiet sleep and exhibited less gross body movement when in active sleep. The results of this pilot study raise the possibility that maternal anxiety during pregnancy may have a significant effect on fetal behavior.

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

This study was undertaken to determine if a relationship existed between the duration of spontaneous general movements before and after birth. Twenty-two infants were examined three times as fetuses between 38 and 40 weeks gestational age and three times as neonates between 2 and 4 weeks postnatal age. Motor activity level during active sleep periods was quantified by direct sonographic visualization for fetuses and by videotaped images of trunk movement for neonates. We found that both fetuses and neonates exhibited stable individual differences in motor activity level. In addition, infants who moved at a certain rate as fetuses generally moved at the same relative rate as neonates up to 4-weeks postnatal age. Our findings suggested that individual differences in motor activity level in the 1st month following birth probably arise during fetal life.

Behavioral state affects heart rate response to low-intensity sound in human fetuses

The cardiac orienting reflex is elicited by a low-intensity sound, it consists of a sustained heart rate (HR) deceleration, and it is a specific physiological correlate of cognitive processing. In this study we examined the relationship between behavioral state and the cardiac orienting reflex in 75 human fetuses between 36 and 40 weeks gestation. Each fetus was stimulated with a 30-s speech sound at an average intensity of 83 dB SPL in quiet sleep (QS) and active sleep (AS). The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz and fetal R-waves were extracted using adaptive signal processing. Fetal behavioral states were assigned based on HR pattern and the presence or absence of eye and general body movements. We found that a significant HR deceleration occurred, in both QS and AS, following stimulus onset. However, HR decelerations occurred more often in QS than AS; and for fetuses exhibiting a HR deceleration, the magnitude of the deceleration was greater in AS compared to QS. In addition, in AS female fetuses exhibited a larger, more sustained HR deceleratory response than male fetuses, but the seconds x gender interaction in QS was not significant. Based on these results, we concluded that behavioral state is an important determinant of the HR deceleratory response in human fetuses.

High vagal tone is associated with more efficient regulation of homeostasis in low‐risk human fetuses

Homeostasis is maintained primarily by the parasympathetic nervous system and is thought to provide a physiological substrate for the development of complex behaviors. This investigation was undertaken to test the hypothesis that infants with high parasympathetic tone are more efficient regulators of homeostasis than infants with low parasympathetic tone. Respiratory sinus arrhythmia (RSA) was used as a measure of parasympathetic tone, and the efficiency of homeostatic control was quantified, for each infant, by the slope (SRSA) and correlation coefficient (RRSA) of the regression line relating fluctuations in heart period and fluctuations in RSA. To test our hypothesis, we examined the relationship between RSA and both SRSA and RRSA in 34 low-risk human fetuses between 36 and 40 weeks gestation. We found that fetuses who were parasympathetic-dominated had larger SRSA and RRSA values, and hence were more efficient regulators of homeostasis, than fetuses who were sympathetic-dominated. The results of our analyses are important because they establish, very early in development, a physiological basis for the relationship between vagal tone and the development of complex behaviors.

Temporal pattern and spectral complexity as stimulus parameters for eliciting a cardiacorienting reflex inhuman fetuses

The purpose of this study was to determine whether temporal pattern and/or spectral complexity were important stimulus parameters for eliciting a cardiac orienting reflex (OR) in low-risk human fetuses. Each of 28 term fetuses was exposed to four sounds formed from the four different combinations of temporal pattern (pulsed, continuous) and spectral complexity (sine wave, IsJ). The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz, and fetal R-waves were extracted by using adaptive signal-processing techniques. We found that pulsed sounds elicited a significantly greater decrease in heart rate (HR) than did continuous sounds. However, the HR response was relatively unaffected by spectral complexity. For the pure tone and the phoneme used in this study, our results indicate that temporal characteristics were more effective at eliciting a cardiac OR in human fetuses than was spectral complexity.

The heart rate deceleratory response in low-risk human fetuses: effect of stimulus intensity on response topography.

The purpose of this study was to determine the effect of stimulus intensity on heart rate response in 18 low-risk human fetuses between 37 and 40 weeks gestation. Each fetus was stimulated in quiet sleep with a 30-s voice sound at intensities of 80 dB and 90 dB. The fetal cardiac electrical signal was captured transabdominally at a rate of 1024 Hz and fetal R-waves were extracted using adaptive signal-processing techniques. We found that fetuses generally exhibited a 5- to 10-s decrease in heart rate following stimulus onset at an intensity of 80 dB. The response pattern changed from deceleratory to acceleratory when stimulus intensity was increased to 90 dB. Our findings suggest that a heart rate deceleration at low-stimulus intensity may be a component of the orienting reflex in the human fetus.

Temporal stability in the distribution of behavioral states for individual human fetuses

Although behavioral state analyses have been useful in differentiating between groups of normal and at-risk fetuses, the large between-subject differences in the percent time spent in the various behavioral states poses a major obstacle in identifying abnormal neurological functioning in individual fetuses. Does this variability represent a true difference in state organization between fetuses, or does it simply reflect individual fluctuations in state control at the time of observation? To answer this question, we examined each of 33 human fetuses for 4 h on three separate days between 38 and 40 weeks gestation. The percent time spent in each behavioral state and in transition and insertion periods was determined for each of the three 4-h study sessions, and within-subject analysis of variance was performed to obtain an objective measure of state profile consistency for each fetus. We found that, on the average, fetuses exhibited remarkable within-subject consistency in their state profiles. However, even among this group of low-risk fetuses, there were significant differences in the degree of state organization achieved by individual fetuses. These findings, which indicate the existence of a well-developed central nervous system before birth, suggest that individual differences in the consistency of behavioral state profiles may be indexing important between-subject differences in neurological development.

MATERNAL ANXIETY DURING PREGNANCY: EFFECT ON FETAL BEHAVIOR AT 38 TO 40 WEEKS OF GESTATION

The purpose of this study was to determine if there is a relationship between fetal behavior and maternal anxiety during pregnancy. The study population consisted of 18 uncomplicated human pregnancies at 38 to 40 weeks gestation. Maternal anxiety was assessed one time using Spielbergers State-Trait Anxiety Inventory. After an overnight fast, each mother was given a standard meal on arrival to the fetal testing unit. Each fetus was examined for 4 hours using heart rate monitoring and real-time sonography. Fetal behavioral states were assigned based on heart rate pattern and the presence or absence of eye and gross body movements. We found that, compared with fetuses of mothers with low trait anxiety scores, fetuses of mothers with relatively high trait anxiety scores spent significantly more time in quiet sleep and exhibited less gross body movement when in active sleep. The results of this pilot study raise the possibility that maternal anxiety during pregnancy may have a significant effect on fetal behavior.

Fetuses and neonates have different heart rate responses to low-intensity stimulation in quiet sleep

Abstract A sustained heart rate (HR) deceleration, elicited by low-intensity stimulation, is considered part of Sokolov’s generalized orienting reflex and is a useful measure of information processing in nonverbal subjects. This study was undertaken to investigate developmental changes in the perinatal period in information processing during quiet sleep (QS). Twenty-six infants were tested as fetuses at 36–40 weeks and again as neonates at a postnatal age of 2 weeks. Quiet sleep was defined in the same way for fetuses and neonates, and the same airborne sound was used for fetal and neonatal testing. We found that stimulation elicited a sustained, monophasic HR deceleration in the majority of fetuses. However, the response was more heterogenous when these infants were tested after birth, with approximately half the 2-week-old infants exhibiting a prolonged HR deceleration and half exhibiting a HR acceleration. These data provide evidence that a developmental change may occur, between the prenatal and postnatal periods, in information processing during QS.

Heart rate dynamics in low risk human fetuses.

Evaluation of nonlinear heart rate (HR) dynamics has received considerable attention in the pediatric literature because such analyses not only provide insight into underlying control mechanisms, but may also help to differentiate between normal and abnormal infants. The purpose of this study was to determine, in eight low risk human fetuses, if nonlinear HR dynamics could be identified by analyzing the dispersion of interbeat intervals at slow (Ds) and fast (Df) HRs. The fetal cardiac electrical signal was captured transabdominally at a resolution of ±1 ms. To test the null hypothesis, that the time series is the result of a linear stochastic process, Ds and Df for the original time series were compared with the values calculated for three linear models. The linear models were constructed to preserve the major statistical properties of the original time series, including the mean, SD, and the Fourier power spectrum. For each fetus, there was no evidence of nonlinear cardiac dynamics based on analyses of Ds and Df. In contrast, the distribution of adjacent R-R intervals and the pattern of change across three successive interbeat intervals both revealed significant nonlinearities in HR control in each fetus. If the difference between normal and abnormal infants is the result of aberrant control of nonlinear processes, then our findings indicate that parameters which describe the nonlinearity may be more useful then Ds and Df in assigning a risk status.