The relation between fetal heart rate accelerations and fetal movements

Fetal heart rate (FHR) accelerations associated with fetal movements is considered a sign of fetal well-being. Fetal movements as felt by the pregnant woman and visualized by real-time ultrasonography were correlated to FHR accelerations in 52 normal and high-risk pregnant women. All fetal movements felt by the mother or seen in the real-time ultrasonography were associated with large FHR accelerations (more than 15 beats per minute lasting 15 seconds or more) or small accelerations (fewer than 15 beats per minute). The large accelerations were associated with 78.6% of fetal movements felt by the mother and 99.6% of fetal movements seen by real-time ultrasonography. The small accelerations were associated with 52.9% of fetal movements felt by the mother and 82.4% of fetal movements seen by ultrasonography. Mothers felt 75.7% of fetal movements seen by real-time ultrasonography. It was concluded that fetal movements could be verified by existence of large accelerations on the FHR tracing.     

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

The association between fetal heart rate (FHR) accelerations and fetal movements during uterine contractions was studied in 52 pregnant women near term or at the beginning of labor. FHR and uterine contractions were recorded by tococardiograph. At the same time, fetal movements, whether associated or not with contractions, were viewed by real-time ultrasound. During uterine contractions, 95.5% of the FHR accelerations were associated with fetal movements. Also, 90.9% of the accelerations which appeared when the uterus was not contracting were associated with fetal movements. Fetal movements were not seen in 91% of uterine contractions which were not associated with FHR accelerations. The suggestion is made that uterine contractions stimulate both fetal movements and FHR accelerations.     

Antepartum fetal heart rate monitoring: III. Fetal movements and accelerations in fetal heart rate

This third part of the paper deals with the study of the relationships between fetal movements, fetal heart rate accelerations associated with such movements, fetal heart rate instability and neonatal outcome.No correlation has been found between absence of fetal movements and neonatal distress.A correlation has been found between the lack of fetal heart rate accelerations, the flatness of the record and poor neonatal outcome.In extreme situations (i.e. flatness in less than 10% of the record or in more than 80%) the presence or absence of accelerations does not add further useful information. Such information, however, is gained in the intermediary situations (the ‘combined’ recordings) and particularly when the record is between 51 and 80% flat where there appears to be an 85.6% risk to the fetus.Consequently, when trying to analyse an antenatal record it seems advisable to take primarily into account the percentage of flat recordings (providing the records are numerous enough and of sufficient length). Then, in records between 10 and 50% flat, the presence or the lack of spontaneous decelerations requires consideration whereas, when the record is between 51 and 80% flat, it is the presence or absence of fetal heart rate accelerations which is important.     

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

Fetal breathing, fetal body movements, fetal heart rate, and fetal heart rate accelerations and decelerations were studied longitudinally in healthy fetuses between 24 and 32 weeks' gestation in the second and third hour following an 800 kcal maternal meal. The expected increase in fetal breathing following a maternal meal was not seen until fetuses were at 30 to 32 weeks' gestation. The number of body movements decreased and the interaction between body movements and fetal heart rate accelerations became more evident as fetuses became older. Fetal heart rate decelerations increased with gestational age, and the relative proportion of total decelerations that were either associated with body movements or were part of a deceleration/acceleration/deceleration complex increased from 24 to 32 weeks' gestation. The data support the hypothesis that gestational age is an important variable to consider when interpreting biophysical measurements in the human fetus at 24 to 32 weeks' gestation. Fetal body movements may be the single most important measurement of fetal health at these gestational ages.     

Evaluation of the fetal movements and accelerations of fetal heart rate in twin pregnancy

In twin pregnancy, the fetal heart rates (FHR) of each fetus and uterine contraction were recorded simultaneously on a single recording chart by two cardiotocographs and a linear multichannel recorder. In addition, with a new technique, FHR and fetal movement (FM) signal bursts for each fetus were recorded similarly on a single recording chart by two ultrasonic Doppler actographs and an electronic polyrecorder. Simultaneous nonstress tests were done for 32 sets of twins at 28 to 41 weeks' gestation. The observed acceleration number in every gestational week increased till 38 weeks and this result was similar to that in singletons. Completely synchronous acceleration patterns in the 2 fetuses were observed in 654 recordings (31.4%) and asynchronous acceleration patterns in 1,108 recordings (53.1%). Simultaneous FHR and FM signal burst recordings were performed in 7 twin pregnancies. In about half of the 1,535 recordings, the FM signal bursts were synchronous between 2 fetuses, whereas they were asynchronous in the other half. Synchronous FM bursts in each gestational week decreased with time. Neurological independency between the twins was suggested by the results. The synchronous appearance of FM signal bursts with FHR accelerations of 2 fetuses was more pronounced in a uniovular twin than in a biovular twin.     

The relationship between movements and accelerations in fetal heart rate at twenty-four to thirty-two weeks' gestation

The purpose of this study was to establish the relationship between fetal heart rate accelerations and fetal body movements in fetuses at 24 to 32 weeks' gestation. The results suggest that body movements in younger fetuses do not occur with accelerations that are readily recognizable (i.e., less than 15 bpm), but as fetuses get older, the interaction between body movements and fetal heart rate becomes more evident and accelerations become more recognizable (i.e., greater than or equal to 15 bpm). The data presented suggest that there is a maturational aspect to the relationship between fetal heart rate and fetal body movements as fetuses increase in gestational age from 24 to 32 weeks. The conclusion, therefore, is that the nonstress test, as presently defined for older fetuses, is not valid for gestations below 32 weeks, and new criteria must be established.     

The relationship between gestational weeks and fetal breathing movements in each pattern of the fetal heart rate

Fetal breathing movement (FBM) was analysed in each fetal heart rate (FHR) pattern and the gestational 2 weeks. FHR pattern was divided in automated FHR analysis into 3 groups; active, intermediate and resting patterns. The patients consisted of 102 pregnant women at 30-41 weeks, including 13 complicated pregnancies. 1) The active pattern percentage was 52.7% at 32-33 weeks and it decreased gradually. That of the resting pattern was 25.5% at 32-33 weeks and it increased gradually. 2) The percentages of positive FBM in the active pattern were significantly larger than those in the resting pattern in each 2 weeks. 3) The duration of continuous FBM ranged from 3 to 202 sec. FBM of long duration tended to exist in the resting pattern rather than in the active pattern. 4) The percent time ratio of FBM ranged from 1.0 to 92.7% and showed no definite relationship with the FHR patterns or gestational weeks. 5) The FBM rates in each FHR pattern showed no significant differences. Their sequential differences after 36 weeks were significant; that is, FBM in the resting pattern was more regular than that in the active pattern. 6) In high risk pregnancy, the resting pattern percentage was 52.3% and the ratio of positive FBM in the resting pattern was significantly smaller than that in active pattern.     

The extent of fetal heart rate accelerations associated with fetal body movements in relation to the duration of fetal body movement

The temporal relations between fetal body movements and associated fetal heart rate accelerations were shown as the ratios of duration of acceleration or acceleration amplitude and the duration of associated fetal body movements in 44 normotrophic and 40 hypotrophic fetuses (body weights within the 6th to 10th percentiles, n = 19, and less than or equal to the 5th percentile, n = 21) between the 36th and 40th gestational weeks. Related to the duration of associated fetal body movements, hypotrophic fetuses proved to have gradually smaller heart rate accelerations than normotrophic fetuses. Moreover, the acceleration parameters duration and amplitude were dependent on the relative duration of fetal body movements. Short fetal body movements were accompanied by fetal heart rate accelerations of relatively highest degree and vice versa. As a consequence, no comparison is possible between temporally different fetal body movements and their associated heart rate accelerations. Of the two acceleration parameters duration and amplitude, the inclusion of the accelerations amplitude in the above mentioned ratio yielded the most obvious results. Taking into consideration that fetuses with intrauterine growth retardation are often in a state of chronic hypoxia, the ratios of acceleration amplitude and durations of associated fetal body movements indicated different degrees of this metabolic situation.     

Fetal heart rate and fetal movements.

Fetal Heart Rate (F.H.R.) in association with fetal movement was evaluated in 141 normal and pathological pregnancies. In the normal cases only 31% showed an acceleration of F.H.R. in association with fetal movement. The majority of the normal cases, 62%, did not demonstrate changes in F.H.R. in association with fetal movement. In the pathological pregnancies there were no characteristic changes in F.H.R. associated with fetal movement. It appears that F.H.R. acceleration associated with fetal movement cannot be used as an index for fetal well being.     

Fetal heart rate accelerations and fetal oxygen pressure sub partu

By means of tcPO2 measurement, a total of 297 FHR accelerations from 55 oxygen cardiotocograms were analysed with regard to their association with changes in fetal oxygen pressure sub partu. It could be demonstrated that the transcutaneous oxygen pressure of 2.3 kPa (17.1 mmHg) with occasional accelerations was significantly (alpha less than 0.05) higher than that of 2.2 kPa (16.6 mmHg) with periodic accelerations. Oxygen pressure with occasional accelerations with "classical parameters" (amplitude greater than or equal to 15 bpm, duration greater than or equal to 15 sec) did not significantly differ from that with one or both parameters below these minimal values. Furthermore, our results suggest the production of periodic accelerations by pressorreceptor reflex due to intermittent disturbance in umbilico-placental perfusion.     

Significance of exaggerated fetal heart rate accelerations during active labor

One hundred fifty-three of 1,289 patients (11.9%) monitored during labor were identified as having exaggerated fetal heart rate accelerations (EFHRAs), defined as accelerations of the fetal heart rate above the baseline of 30 beats/min or greater and lasting at least 30 seconds. Comparisons of patients with and without EFHRAs showed that the only difference between the two groups was a higher percentage of nulliparous patients in the EFHRA group. Comparisons of intrapartum complications showed a decreased incidence of meconium staining and an increased percentage of abnormal labor patterns in the EFHRA group. Comparisons of neonatal outcome statistics showed lower perinatal morbidity and higher mean birth weight in the EFHRA group.     

The relationship between antepartum fetal heart rate, intrapartum fetal heart rate, and fetal acid-base status

The relationships between antepartum baseline fetal heart rate, baseline variability, accelerations, decelerations, and fetal movement and intrapartum fetal heart rate, fetal acid-base assessment at delivery, and Apgar scores 1 and 5 minutes after delivery were studied in 290 mature pregnancies. There was a significant relationship between antepartum and intrapartum baseline fetal heart rate and baseline variability. There was no relationship between antepartum and intrapartum accelerations or decelerations. There was no correlation between antepartum fetal heart rate or fetal movement and fetal acid-base status at delivery or Apgar scores 1 and 5 minutes after delivery. There was a trend for decreased accelerations and decreased fetal movements to be associated with a low Apgar score 1 minute after delivery.     

Antepartum fetal evaluation by assessment of fetal heart rate and fetal movements

Three antenatal monitoring tests--fetal movement acceleration test (FMAC-test), fetal heart rate-nonstress test (FHR-NST), and daily fetal movement recording (DFMR) were evaluated in 212 high risk pregnant women. While in 196 cases all three tests were normal, in 16 patients one to three tests showed pathological results. In the latter group, there was a significantly higher incidence of perinatal mortality, low Apgar score and growth retardation. Since false positives are known to occur in these tests, at least two should be pathological to warrant delivery in am attempt to prevent fetal death in utero. The sequence in which the pathology appears in the deteriorating fetus is as follows: the first to become non-reactive is the FMAC-test, followed by decreased fetal movements till cessation, and, finally, severe changes in the FHR-NST take place. The importance of this sequence of events is discussed.     

Coupling of fetal movement and fetal heart rate accelerations as an indicator of fetal health.

OBJECTIVE: The purpose of this study was to determine the clinical value of identified coupling of fetal heart rate (FHR) accelerations (more than five beats per minute for any duration) with objectively detected fetal movements. METHODS: One hundred sixty-six patients underwent routine fetal testing using a Doppler device that recognized both FHR and fetal movements. The coupling index was determined to be the percentage of fetal movements associated with FHR accelerations, and various coupling indices were compared with nonstress test (NST) results. RESULTS: A coupling index above 25% and below 75% compared well with the traditional NST by standard epidemiologic criteria and by the kappa statistic. CONCLUSION: Coupling of even small FHR accelerations and fetal movements could substitute for or replace the NST in antenatal screening.     

Intrauterine breathing movements and fetal presentation

Fetal breathing movements in 14 twin pregnancies were examined with ultrasonic technique. The twin fetuses I in cephalic presentation showed a significantly higher percentage of apnea and periodic breathing compared with twin fetuses II. No such difference was found in twin pairs with Twin ti in breech presentation. Also in the control group of 27 singleton pregnancies, the fetuses in cephalic presentation had a higher incidence of apnea and periodic breathing than those in breech presentation. The position of the fetus seems to be decisive for the character of the breathing movements before birth.