Antenatal Fetal Heart Rate Monitoring Research Articles

Validation of beat by beat fetal heart signals acquired from four-channel fetal phonocardiogram with fetal electrocardiogram in healthy late pregnancy

Fetal heart rate monitoring is an essential obstetric procedure, however, false-positive results cause unnecessary obstetric interventions and healthcare cost. In this study, we propose a low cost and non-invasive fetal phonocardiography based signal system to measure the fetal heart sounds and fetal heart rate. Phonocardiogram (PCG) signals contain acoustic information reflecting the contraction and relaxation of the heart. We have developed a four-channel recording device with four separated piezoelectric sensors harnessed by a cloth sheet to record abdominal phonogram signals. A multi-lag covariance matrix based eigenvalue decomposition technique was used to extract fetal and maternal heart sounds as well as maternal breathing movement. In order to validate the fetal heart sounds extracted by PCG signal processing, 10 minutes’ simultaneous recordings of fetal Electrocardiogram (fECG) and abdominal phonogram from 15 pregnant women (27 ± 5-year-old) with fetal gestation ages between 33 and 40 weeks were obtained and processed. Highly significant (p < 0.01) correlation (r = 0.96; N = 270) was found between beat to beat fetal heart rate (FHRECG) from fECG and the same (FHRPCG) from fetal PCG signals. Bland–Altman plot of FHRECG and FHRPCG shows good agreement (<5% difference). We conclude that the proposed beat to beat fetal heart rate measurement system would be useful for monitoring fetal neurological wellbeing as a better alternative to traditional cardiotocogram based antenatal fetal heart rate monitoring.

Telemetric antenatal fetal monitoring.

Extracted from text ... September 2005, Vol. 11, No. 3 71 SAJOG The origin of antenatal fetal heart rate monitoring (AFM) appears lost in the mists of time. Odendaal, 1 in his signal thesis on cardiotocography, mentions that Legumeau de Kegadarek had first observed the occurrence of fetal heart rate decelerations in 1822, after which Von Winckel, in 1893, observed that bradycardia may be associated with poor fetal outcome. Electronic AFM has remained an integral part of obstetric practice since the early 1970s, when continuous monitoring became established and the true significance of decelerations was appreciated. Developing communities often have inordinately high perinatal mortality ..

The Role of Doppler Velocimetry in the Management of High Risk Pregnancies

Objective To determine whether knowledge of the result of Doppler velocimetry of the umbilical artery is beneficial to the management of a high risk pregnancy. Design Randomised controlled trial. The trial was of the management type, designed to assess benefit accruing from additional information supplied by Doppler velocimetry. Setting Tygerberg Hospital, Cape Town, South Africa. The hospital serves a population from the lower socio-economic groups. Subject Women with pregnancies 28 or more weeks gestation with hypertensive diseases and/or suspected small for gestational age fetuses were referred for Doppler velocimetry. From this population, three subsets were formed: 1. those with fetuses with absent end-diastolic velocities (20 fetuses); 2. those with hypertension but with fetuses with end-diastolic velocities (89 fetuses); and 3. those with fetuses suspected of being small for gestational age but with end-diastolic velocities (104 fetuses). Interventions Doppler velocimetry on all subjects. The study group consisted of 10 cases with absent end-diastolic velocities, 47 cases with hypertensive diseases with end-diastolic velocities and 51 cases with suspected small for gestational age fetuses but with end-diastolic velocities in which the result was revealed to the clinician. The control group consisted of 10, 42 and 53 cases, respectively, in which the Doppler results were not revealed. All other routine investigations (sonar and antenatal fetal heart rate monitoring) were available to the clinicians. Standard management protocols were followed in all groups. Main outcome measures Perinatal mortality and morbidity, antenatal hospitalisation, maternal intervention, admission to the neonatal intensive care unit and hospitalisation until discharge from the neonatal wards. Results In the study and control groups the gestational age at entry to the study, maternal age, parity and various complications were not significantly different. In the subset with absent end-diastolic velocities, there was one neonatal death in the study group, but in the control group there were six deaths, five intrauterine and one perinatally related infant death (P= 0.029). Because of this significant finding, the study was stopped. There were no differences in outcome in the subset where there was hypertensive disease with end-diastolic velocities between the study and control groups. In the subset in which small for gestational age fetuses were suspected, but in which end-diastolic velocities were present, the women in the study group had significantly fewer days in hospital before delivery (P < 0.001) and tended to have fewer maternal interventions (study group = 27%, control group = 43%; P= 0.07; odds ratio (OR) 0.49, 95% confidence limits (CL) 0.2 and 1.25) and caesarean sections (study group =13%, control group = 27%; P= 0.08; OR 0.43, 95% CL 0.14 and 1.32). The infants of the study group in this subset also spent significantly less time in the neonatal wards (P= 0.029). Conclusions Within the confines of this study, knowledge of the Doppler velocimetry result was beneficial in the subsets with absent end-diastolic velocities and in which intrauterine growth retardation was suspected. In the subset in which women had hypertension but whose fetuses had end-diastolic velocities, there was no beneficial or adverse effect.

The role of Doppler velocimetry in the management of high risk pregnancies

To determine whether knowledge of the result of Doppler velocimetry of the umbilical artery is beneficial to the management of a high risk pregnancy. Randomised controlled trial. The trial was of the management type, designed to assess benefit accruing from additional information supplied by Doppler velocimetry. Tygerberg Hospital, Cape Town, South Africa. The hospital serves a population from the lower socio-economic groups. Women with pregnancies 28 or more weeks gestation with hypertensive diseases and/or suspected small for gestational age fetuses were referred for Doppler velocimetry. From this population, three subsets were formed: 1. those with fetuses with absent end-diastolic velocities (20 fetuses); 2. those with hypertension but with fetuses with end-diastolic velocities (89 fetuses); and 3. those with fetuses suspected of being small for gestational age but with end-diastolic velocities (104 fetuses). Doppler velocimetry on all subjects. The study group consisted of 10 cases with absent end-diastolic velocities, 47 cases with hypertensive diseases with end-diastolic velocities and 51 cases with suspected small for gestational age fetuses but with end-diastolic velocities in which the result was revealed to the clinician. The control group consisted of 10, 42 and 53 cases, respectively, in which the Doppler results were not revealed. All other routine investigations (sonar and antenatal fetal heart rate monitoring) were available to the clinicians. Standard management protocols were followed in all groups. Perinatal mortality and morbidity, antenatal hospitalisation, maternal intervention, admission to the neonatal intensive care unit and hospitalisation until discharge from the neonatal wards. In the study and control groups the gestational age at entry to the study, maternal age, parity and various complications were not significantly different. In the subset with absent end-diastolic velocities, there was one neonatal death in the study group, but in the control group there were six deaths, five intrauterine and one perinatally related infant death (P = 0.029). Because of this significant finding, the study was stopped. There were no differences in outcome in the subset where there was hypertensive disease with end-diastolic velocities between the study and control groups. In the subset in which small for gestational age fetuses were suspected, but in which end-diastolic velocities were present, the women in the study group had significantly fewer days in hospital before delivery (P < 0.001) and tended to have fewer maternal interventions (study group = 27%, control group = 43%; P = 0.07; odds ratio (OR) 0.49, 95% confidence limits (CL) 0.2 and 1.25) and caesarean sections (study group = 13%, control group = 27%; P = 0.08; OR 0.43, 95% CL 0.14 and 1.32). The infants of the study group in this subset also spent significantly less time in the neonatal wards (P = 0.029).

Antenatal cardiotocography in the evaluation of fetal well-being.

Antenatal fetal heart rate monitoring is a reliable tool to detect the fetus at risk. In the interpretation of records, however, due account must be taken of maturation and fetal behavioural status. In this article the normal heart rate pattern throughout gestation is described. Visual quantitative and descriptive scoring systems are compared and the consequences of interobserver variability in assessing antenatal heart rate records are discussed. It is postulated that there is only a small--if any--place for oxytocin stress testing. Finally the clinical implications of the different fetal heart rate patterns are presented.

Combined (stressed and non-stressed) antenatal fetal heart rate monitoring

Acceleration patterns of the fetal heart rate, or a normal heart rate during spontaneous contractions, were used as a short weekly screening test to evaluate fetal well-being in 1102 high-risk pregnancies. When accelerations or contractions were absent during the initial screening, oxytocin was administered to stimulate uterine contractions. The mean duration of the antenatal monitoring was 18.5 min when the initial antenatal monitoring was normal, but 38.8 min when the initial results were uncertain. Oxytocin was administered to 38% of patients. This reduced the number of occasions where the diagnosis was uncertain from 46.6% to 12%. Patients with uncertain antenatal fetal monitoring had significantly more late decelerations during labor as well as newborns with low Apgar scores when compared to those with normal antenatal monitoring. Patients with abnormal antenatal monitoring (positive stress test) had significantly more low 5-min Apgar scores, late decelerations during labor and growth-retarded infants than the patients with normal antenatal fetal monitoring. Only 1 intrauterine death occurred within 7 days of a normal antenatal heart rate recording. No preventable fetal deaths occurred when antenatal monitoring demonstrated an acceleration pattern of the fetal heart rate.

EVALUATION OF FETAL WELLBEING BY ANTEPARTUM FETAL HEART MONITORING

The value of antenatal fetal heart rate monitoring was assessed in 301 patients. Tracings from each patient were classified as reactive or non-reactive. Perinatal mortality, fetal distress in labour, caesarean section for fetal distress, and the incidence of low Apgar scores were all significantly increased in the non-reactive group.

Evaluation of fetal wellbeing by antepartum fetal heart monitoring.

The value of antenatal fetal heart rate monitoring was assessed in 301 patients. Tracings from each patient were classified as "reactive" or "non-reactive." Perinatal mortality, fetal distress in labour, caesarean section for fetal distress, and the incidence of low Apgar scores were all significantly increased in the non-reactive group.

Antenatal Fetal Heart Rate Monitoring

Summary: The value of antenatal fetal heart rate monitoring has been studied in 110 patients. When the fetal heart rate pattern was normal, the fetal outcome was satisfactory. When abnormalities of the fetal heart rate were present there was an increased incidence of fetal distress in labour, and reduced Apgar scores at 1 and 5 minutes. The place of fetal heart rate monitoring in antenatal care is discussed.