Fetal Movement Rate Research Articles

The Actifetus System: A Multidoppler Sensor System for Monitoring Fetal Movements

Fetal heart rate (FHR) monitoring is a crucial part of monitoring at-risk pregnancies and labor. Its aim is to detect any abnormalities that might indicate acute fetal distress and a need for rapid treatment to avoid death or serious sequelae, including cerebral handicap. The use of fetal biophysical profiles in high-risk pregnancies (gravidic hypertension, in utero infection, etc.) helps to distinguish healthy fetuses from those with chronic conditions. Fetal biophysical profile scores have been developed that integrate five biophysical parameters, one of which is derived from the FHR. The major parameters detected are the rate of fetal movements, fetal tone, fetal breathing movement and amniotic fluid volume. All of those parameters except FHR are obtained by prolonged echographic observation and cannot be used routinely. We developed in this study a new multigate multitransducer pulsed Doppler system for survey of fetal behavior. Fast Fourier transform and autocorrelation function have been used for processing and analyzing ultrasonic Doppler signals generated by fetal movements. Several parameters are analyzed in each of the 12 × 5 = 60 Doppler gates: amplitude of signals reflected by moving fetal structures, velocity, direction and amplitude of displacement of fetal structure (heart, chest, limbs). From these parameters it is possible to calculate FHR and characterize fetal activity. Preliminary in vivo results obtained in 15 pregnant women (30 to 36 wk) are very encouraging but they have yet to be confirmed in future studies. These results also demonstrate the advantages of transducers designed for improved fetal movement detection. The algorithms needs to be precise enough to allow the Actifetus system to function in real time. We now have at our disposal some algorithms that succeed in quantifying FHR and fetal movements with a signal from a given sensor at a given depth. This study confirms the feasibility of monitoring fetal movements by the Actifetus system and demonstrates the importance of the characterization of fetal rhythms (and fetal behavior). The Actifetus system will serve as a new mean for studying fetal response to environment and detecting anomalies related to fetal suffering. (E-mail: ali.kribeche@med.univ-tours.fr)

Incidence of Spontaneous and Evoked Fetal Movements in the First Half of Twin Pregnancy

Fetal movements (FM) may be spontaneous, originating in the fetus itself, or evoked, caused by external stimuli. The FM in 21 normal twin pregnancies at 10 and 21 weeks of gestation were studied. The percentage rate of evoked FM which occur simultaneously in both twins was 4.96% of all observed FM. The rate of the spontaneous FM which occur independently in each fetus was 95.04% of all FM. The low incidence of evoked FM, at an early gestational age (10-21 weeks) emphasizes the ability of these young fetuses to perceive external stimuli and to react to them by FM.

Ultrasonographical evaluation of the incidence of simultaneous and independent movements in twin fetuses.

Fetal movements (FM) may be spontaneous, originating in the fetus itself, or evoked by external stimuli. The relative rate of spontaneous and evoked FM has not yet been documented. As it is impossible to differentiate in a singleton pregnancy between these types of movements - the natural model of twin pregnancy was used. The FM of 10 normal twin pregnancies between 33 and 39 weeks of gestation were studied by two realtime ultrasounds, and were operated by two ultrasonographers over a period of 10 min. The mean number of independent FM of each fetus which occurred while the other fetus was resting was 7.9 FM and 7.7 FM, respectively (average 7.8 FM). A mean of 2.5 FM occurred simultaneously. The rate of independent FM was 75.7% and that of simultaneous FM was 24.3%. Vibroacoustic stimulation applied to the maternal abdomen evoked simultaneous movements of both fetuses in all cases. It is suggested that the independent FM may represent spontaneous FM and that the simultaneous FM may indicate the presence of an external stimuli and are therefore evoked responses.

Incidence of spontaneous and evoked fetal movements.

Fetal activity is composed of fetal movements (FM), which are either nonreflexive, originating in the fetus itself, or evoked reflexive FM which are stimulated by the fetal environment. The relative ratio of the spontaneous to evoked FM has not yet been documented. Since it is impossible to differentiate in a singleton pregnancy between these two types of FM on the basis of maternal perception alone, the natural model of twin pregnancy was used. It has previously been shown that the number of FM in a singleton pregnancy is similar to that of each individual fetus in a twin pregnancy of the same gestational age. It was assumed that the factors which cause spontaneous and evoked FM are similar in singleton and twin pregnancies. The fetal activity in 44 twin and 76 singleton pregnancies between 28 and 39 weeks of gestation was assessed during 20 min of nonstress test recording. The means of FM in twins were significantly higher than those in singleton pregnancies. The rate of the spontaneous FM was calculated to be 50-59% of all FM in singleton pregnancies and that of the evoked FM 41-50%.

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drops per minute according to the clinical effect. Isox­ suprine was discontinued 4 hours after control of the contractions was obtained. This was usually obtained after 12 to 36 hours, and then oral administration was started with 10 mg of isoxsuprine every hour. Within several days the oral dose was gradually reduced to 5 mg eight times daily. The total duration of hospitaliza­ tion was between 4 and 84 days. The rate of reduction of the dose was governed by the frequency of the uterine contractions which caused pains and side effects, such as weakness or tachycardia. When the oral regimen of isoxsu prine was started, the women were asked to assess fetal movements felt during a period of 30 minutes three times daily (morn­ ing, noon, and evening, after meals and while lying in bed on their side). The number of fetal movements calculated for 12 hours constituted the daily fetal movement recording. The mean daily fetal movement rate expresses the mean of the number of cases each individually calcu­ lated for daily average of weekly counts. Statistical analysis of the difference between the daily fetal movement rate in the ,8-mimetic-treated group and the control group at the same week of gestation was carried out with Student's t test. Table I shows the daily fetal movement rate (mean ± SD) according to the week of gestation in 102 isoxsu­ prine-treated patients between the twenty-sixth and thirty-sixth weeks of pregnancy as compared with the results of our previous study,3 in which weekly averages of daily fetal movement recordings of singleton preg­ nancies in 127 pregnant women with good outcome were presented. Table I shows that there was no significant difference in the mean daily fetal movement rate in the ,8mimetic-treated group as compared to the control group. The results of the present study show that the mean fetal activity in isoxsuprine-treated pregnant women is similar to that of the control normal pregnancies. These findings are supported by Rayburn. 4 The results also show that the pattern of fetal activity in the ,8-mimetic-treated group resembles that of the control group by increasing from the twenty-sixth week, with a plateau in the twenty-ninth to thirty­ second weeks, and then decreasing thereafter. Thus, cases of threatened premature delivery treated with isoxsuprine can be screened by fetal movement assess­ ment for the diagnosis of fetal jeopardy as in other high-risk pregnancies.

Fetal movements and intrauterine growth retardation

Fetal Movement (FM) rate was evaluated in cases of symmetrical and asymmetrical intrauterine growth retardation (IUGR) and was compared to the FM rate in normal pregnancy. In the 25–36th week of gestation there was a significant decrease of FM rate in both groups of IUGR which was more pronounced in the symmetrical group. Also shown, was a gradual trend of increase of the FM rate with advancing gestational age in both groups of IUGR. Cases of asymmetrical IUGR were noted, who had markedly decreased FM until cessation. In this group of IUGR decreased FM demands prompt hospitalization and fetal heart rate monitoring so that possible respiratory failure and impending fetal death can be detected.