Human fetal responses to sound as a function of stimulus intensity.

Longitudinal measurements of fetal breathing, body movements, heart rate, and heart rate accelerations and decelerations at 24 to 32 weeks of gestation

Observation of fetal movement and fetal heart rate (FHR) responses to repeated vibroacoustic stimulation (VAS) might be useful as a measure to assess fetal well-being and to assess the integrity of the fetal central nervous system (CNS). We observed the movement and FHR responses to repeated VAS of a term fetus with a serious brain anomaly as compared to responses of normal term fetuses. In 37 normal term fetuses and in a term fetus with an encephalocele we studied movement and FHR response to repeated VAS. All normal fetuses responded within 1 s after stimulation with general body movement and FHR acceleration. At 36 gestational weeks, no movement or FHR responses were seen in the fetus with an encephalocele. Repetition of the test in this fetus after one week still showed no response to repeated VAS. Normal fetuses showed movement and FHR responses to external stimulation. The fetus with an encephalocele did not respond to repeated VAS with a movement or FHR acceleration. Case studies in fetuses with structural anomalies of the CNS are needed to gain insight into the spectrum of possible responses to VAS.

Thirty women were studied to examine the effect of fetal scalp stimulation on fetal heart rate (FHR) accelerations and gross body movements in quiet and active fetal behavioral states during the active phase of labor. Stimulation was performed by five consecutive tractions of the fetal scalp electrode. Fetal response in terms of fetal movements and FHR accelerations occurring within 15 seconds after stimulation was observed in all fetuses of the active state group. In the quiet state group 14 of 15 fetuses responded with body movements and in 12 fetuses FHR accelerations were observed. Subsequently, most of the fetuses returned to the quiet state. We suggest that a normal and healthy fetus is expected to respond to the fetal scalp electrode stimulation test even in the quiet behavioral state.

Use of sound-elicited fetal heart rate accelerations to assess fetal hearing in the second and third trimester

The presence of fetal heart rate (FHR) accelerations is considered a sign of fetal well-being. Fetal body and breathing movements, as visualized by real-time ultrasound, were correlated to FHR accelerations in 16 high-risk pregnancies. The association between FHR accelerations (greater than 15 beats/min lasting 15 sec or more) and the different fetal behavioral states is described.

The relationship between fetal heart rate accelerations, fetal movements, and uterine contractions

We measured duration, amplitude, and duration at peak amplitude of 117 heart rate accelerations of 12 normal fetuses greater than 36 weeks gestation. Fetal movement measured by Doppler was analyzed for duration of movement; number of limb, spine, and rolling movements; and total movements per epoch of movement. Of 117 accelerations, only five were not associated with recorded movement and all of these had amplitude less than 12 bpm and duration less than 16 seconds. Only four (3%) accelerations occurred before fetal movement was detected, 23 (20%) began after onset of movement, and the large majority (77%) of fetal heart rate (FHR) accelerations occurred synchronously with fetal movement. In addition to an obvious correlation between number of movements and time spent in movement, a relationship exists between movements and duration of accelerations. Movements do not correlate with amplitude of accelerations. Fetal movement and heart rate acceleration relate temporally, but the strength or type of movemen...

The risk of intraventricular hemorrhage and periventricular leukomalacia correlates with fetal brain immaturity. Given that the appearance of fetal heart rate (FHR) accelerations is associated with brain maturation, we tested the hypothesis that neonatal cerebral lesions and developmental delay in very low birthweight newborns are associated with absent reactivity of the FHR tracing prior to delivery. We analyzed the FHR tracing of 97 fetuses with birthweight < 1200 g who underwent head ultrasound at day 3 and Bayley Scales of Infant Development testing at age 1 year. We used multivariate analysis to adjust for confounding variables. We found that the absence of two FHR accelerations of 10 beats per minute (bpm) for 10 seconds twice in a 20-minute window 1 hour before delivery was associated with intraventricular hemorrhage and/or periventricular leukomalacia ( P < 0.01) and a significant risk for mental and psychomotor delays by Bayley testing ( P < 0.001). The absence of accelerations of 15 bpm for 15 seconds was not associated with these abnormalities. The absence of FHR accelerations before delivery suggests a greater risk for cerebral injury and developmental delay in the very premature neonate.

Effect of intravenous glucose injection on human maternal and fetal heart rate at term

Fetal responses to vibratory acoustic stimulation: Influence of basal heart rate

Aims To study fetal brain response to fetal movements with fetal heart rate (FHR) changes. Methods FHR changing mechanism was investigated by simultaneously recorded FHR and fetal movements detected directly at fetal thorax with Doppler ultrasound in act cardiogram (ACG). FHR changing process was confirmed by electronic and physiologic simulations. Results and conclusion As recorded movement spike height was parallel to fetal movement amplitude in ACG, FHR increased when the fetus moved, and triangular FHR acceleration developed at fetal movement burst by the integral function of midbrain. Moderate fetal movements developed moderate FHR increase, and periodically changing fetal movements developed physiologic sinusoidal FHR separating pathologic sinusoidal one. FHR variability developed by minor fetal movements. FHR acceleration was lost in early stage of hypoxia, and then the loss of variability comparable to anencephaly appeared in severe hypoxic fetal brain damage, followed by cerebral palsy. Thus, early delivery is recommended before the loss of variability, instead of C-section after the loss of variability. Rabbit heart rate reduced along PaO2 drop, where parasympathetic centre was excited in medulla oblongata by low PaO2 developing fetal bradycardia, which showed environmental hypoxia, whereas the loss of variability was full brain damage due to severe hypoxia, where fetal brain could not respond fetal movements as anencephaly.

To determine the influence of diurnal variation in maternal movements (MM) on fetal heart rate (FHR) accelerations, 24-hour maternal heart rates (MHR), MM and FHR recordings were made simultaneously on nine healthy pregnant women at 36-39 weeks of gestation. Correlations between the diurnal variations in maternal factors and FHR parameters; that is, baseline FHR, amplitude, duration and hourly percentage of time spent in accelerations, were examined. Only a few cases showed a significant correlation between acceleration parameters and the diurnal variation of MHR or MM, while most cases indicated a high correlation between the diurnal variation in baseline FHR and that of maternal factors. In conclusion, the occurrence and form of accelerations might be independent of maternal activity.

The results of the concomitant monitoring of the fetal heart rate and the total fetal movement activity by two ultrasound monitors are reported. In 111 patients from 26 weeks gestation to term the cardiotocogram and the fetal movement activity were at the same time monitored with two ultrasound monitors. In total 453 fetal heart rate accelerations of more than 15 beats per minute and more than 15 seconds duration were found in all cardiotocograms. The most frequent finding with an acceleration of the fetal heart rate were fetal body movements with or without movements of the extremities in 71% of the fetal heart rate accelerations. In 18% of the fetal heart rate accelerations movements of the fetal extremities were found by ultrasonography. In 7% of the fetal heart rate accelerations, fetal respiratory movements or contractions were found without fetal body movements. 4% of the fetal heart rate accelerations occurred without sonographically or topographically recognizable cause. In all ultrasonographically recognized fetal movements of the body and/or the extremities the fetal heart rate accelerations occurred in 28% of the cases. The most frequent findings were movements of the fetal body with or without movements of the fetal extremities in 48% of the fetal heart rate accelerations. In isolated movements of the fetal extremeties the fetal heart rate was only accelerated in 11% of the cases.

Fetal Brain Behavior and Cognitive Development

Objective. To analyze typical maternal heart rate (MHR) patterns in the first and second stages of labor. Design. Observational study. Setting. Tertiary care community hospital. Population. Normal term parturients with epidural anesthesia. Methods. Confirmed MHR and uterine activity were simultaneously recorded. The average MHR was analyzed 10 seconds before, as well as at the peak of, each contraction and/or pushing effort. Each woman contributed one datapoint at each time point to the analysis. Main outcome measure. Change in MHR during contractions. Results. First stage: 7.6±2.1 contractions per woman (n=18) were analyzed. Average MHR decreased during contractions: from 83±13 to 74±10bpm; p<0.001). In 56% (10/18) of the women, 'early' type decelerations were seen in at least 50% of contractions. Second stage: 3.5±1.5 contractions per woman. All women (n=15) showed MHR accelerations during every pushing effort (ΔMHR: +35±13bpm; 88±14 to 123±17bpm; p<0.001). MHR was persistently >100bpm in three women (17%) in the first stage, and in four women (27%) in the second stage. Peak MHR >140bpm occurred during pushing in 20%. Conclusion. Decreases in MHR during contractions in the first stage of labor can mimic fetal heart rate (FHR) accelerations as well as early type decelerations. Thus, first stage tracings with a low baseline and early type decelerations may be maternal in origin and FHR should be independently confirmed in such tracings. Because second stage MHR accelerations generally show greater amplitude than FHR accelerations, tracings with repetitive accelerations during contractions (especially when Δ >20bpm) should be considered MHR until proven otherwise.