Fetal Heart Rate Measurements Research Articles

The development of an obstetric tele-monitoring system.

Fetal growth restriction and preterm uterine contractions can turn a normal pregnancy into a problematic one. In previous work, we have developed a system for electrophysiological measurement of fetal heart rate (fHR), fetal electrocardiogram (fECG) and (premature) uterine contractions to enable early detection of foetal problems. In this work we have expanded this system into a tele-monitoring system for measurement at home. In order to permit home monitoring, the communication chain of the data has to be designed such that home-measured signals (fHR, fECG, uterine activities) are available in the hospital in real-time. Furthermore, the data must be transferred wirelessly to any location (worldwide) for interpretation by gynaecologists. A web application helps the gynaecologist or midwife to access the signals everywhere, provided that internet access is available. We developed a webserver as the heart of the entire system; it manages the patient database, transforms the signals in a graphical representation similar to that of the cardiotocography and manages the data communication with the proper data security policy. This tele-monitoring system can be used also during home deliveries enabling prompt transfer and proper intervention in the hospital when complications occur.

Fetal QRS detection and heart rate estimation: a wavelet-based approach

Fetal heart rate monitoring is used for pregnancy surveillance in obstetric units all over the world but in spite of recent advances in analysis methods, there are still inherent technical limitations that bound its contribution to the improvement of perinatal indicators. In this work, a previously published wavelet transform based QRS detector, validated over standard electrocardiogram (ECG) databases, is adapted to fetal QRS detection over abdominal fetal ECG. Maternal ECG waves were first located using the original detector and afterwards a version with parameters adapted for fetal physiology was applied to detect fetal QRS, excluding signal singularities associated with maternal heartbeats. Single lead (SL) based marks were combined in a single annotator with post processing rules (SLR) from which fetal RR and fetal heart rate (FHR) measures can be computed. Data from PhysioNet with reference fetal QRS locations was considered for validation, with SLR outperforming SL including ICA based detections. The error in estimated FHR using SLR was lower than 20 bpm for more than 80% of the processed files. The median error in 1 min based FHR estimation was 0.13 bpm, with a correlation between reference and estimated FHR of 0.48, which increased to 0.73 when considering only records for which estimated FHR > 110 bpm. This allows us to conclude that the proposed methodology is able to provide a clinically useful estimation of the FHR.

Prediction of spontaneous miscarriage risk by the use of first trimester ultrasound measurements and maternal serum progesterone level at the 7th week of pregnancy

Abstract Study objective To evaluate the accuracy of using first trimester ultrasound markers such as mean gestational sac diameter (MGSD), crown-rump length (CRL), MGSD:CRL ratio and fetal heart rate (FHR), plus progesterone level at the 7th week of pregnancy to predict spontaneous miscarriage risk. Design A prospective diagnostic accuracy study. Setting Ain Shams University Maternity Hospital. Materials and methods Included women were recruited from those attending antenatal outpatient clinics during the 7th week of gestation. Transvaginal sonography was performed for all women for confirmation of the gestational age and measurements of MGSD, CRL and FHR. Blood samples were collected at the same time for the measurement of serum progesterone level. All pregnancies were followed up till the completion of the 20th week of pregnancy. Main outcome measure Spontaneous miscarriage occurring before or at the 20th week of gestation. Results A total of 200 women were divided into two groups: Group 1 ( n = 23), women who miscarried (miscarriage group) and group 2 ( n = 177) included women who continued after the 20th week of pregnancy (control group). Women in group 1 had significant lower MGSD, MGSD–CRL ratio, and FHR compared to those of group 2. While, there were no significant differences between both groups regarding CRL and progesterone level. The best cut off point for MGSD is 14 mm with a sensitivity and specificity of 96% and 74%, respectively. The best cut off point for CRL is 5.5 mm with a sensitivity of 58% and specificity of 60%. The best cut off point for MSD–CRL ratio is 9 with sensitivity and specificity of 97% and 73%, respectively. The best cut off point for FHR is 111 beat/min with a sensitivity and specificity of 92% and 91%, respectively. For progesterone, the best cut off point is 27 ng/ml with a sensitivity and specificity of 63% and 56%, respectively. Major conclusions To predict spontaneous miscarriage risk at the 7th week of pregnancy, MGSD, MGSD–CRL ratio and FHR, were considered highly valid markers and better positive than negative with higher sensitivity compared to progesterone and CRL.

Fetal heart rate and motor activity associations with maternal organochlorine levels: results of an exploratory study

Contemporaneous associations between circulating maternal organochlorines (OCs) and measures of fetal heart rate and motor activity were evaluated. A panel of 47 OCs, including pesticides and polychlorinated biphenyls (PCBs), was analyzed from serum of 50 pregnant women at 36 weeks gestation. Data were empirically reduced into four factors and six individual compounds. All participants had detectable concentrations of at least one-quarter of the assayed OCs and, in general, higher socioeconomic level was associated with higher OC concentrations. Fetal heart rate measures were not consistently associated with maternal OCs. In contrast, one or more indicators of greater fetal motor activity were significantly associated with higher levels of the DDT and low chlorinated OC factors and five of the six individual compounds (heptachlor epoxide, trans nonachlor, oxychlordane, and PCBs 18 and 52). This preliminary demonstration of associations between fetal motor activity and maternal concentrations of persistent and pervasive environmental contaminants suggests that fetal assessment may be useful in ascertaining the potential early effects of these compounds on development.

A mathematical model of nutrient delivery during labour: predicting fetal distress due to severe acidemia

The mainstay of human labour monitoring, fetal heart rate (FHR), has low positive predictive value (PPV) for severe acidemia, which is associated with increased risk for brain injury. Fetal electroencephalogram (EEG) is feasible during labour and FHR-EEG monitoring would improve the detection of early onset of acidemia. The physiological challenge is generalizing the observations on the dynamic FHR-EEG interaction predictive of incipient severe acidemia from a limited spectrum of FHR-EEG responses that can be induced in vivo. We present a mathematical model that includes blood flow to the heart and brain, so that model output corresponds to FHR and EEG measurements. Model simulations are compared to FHR and EEG data from fetal ovine studies and show a qualitatively good fit: The coherence shows a correlation between ECOG and FHR signals when occlusion is severe, identical to that seen in experimental data. Fuzzy Entropy for simulated ECOG at four occlusion levels distinguishes severe occlusion from less severe levels. In conclusion, our heart-brain oscillator model, coupled by the nutrient flow, reproduces some of the salient dynamics observed in the data. In silico derived theoretical conclusions can be tested in vivo and against clinical data, suggesting new diagnostic criteria of fetal acidemia associated with cerebral compromise for timely intervention during labour.

First trimester volumetric measurements: relation with hormone levels and fetal heart rate

This study aimed to examine two-dimensional ultrasound (2D US) volumetric measurements of 1st trimester structures and their relationship with β-hCG, progesterone, and fetal heart rate (FHR) in 6-10 weeks healthy pregnant women. Using conventional 2D transvaginal ultrasound imaging, the crown rump length (CRL), yolk sac (YS) and gestational sac (GS) were measured in 80 women. Volumetric measurements were done in 32 cases that were selected among 80 women, using a simplified formula for the volume of a prolate ellipsoid: V = 0.523 × length × height × width. The β-hCG and progesterone levels were recorded. The heart rate was determined from M-mode tracings using electronic calipers. Moderately positive correlation was found between FHR versus CRL, embryo volume and GS volume. FHR increased linearly with CRL value, till CRL became 15 mm, after which it formed a plateau. β-hCG increased linearly till CRL was 15 mm, and then it formed a plateau. Progesterone level was stable till CRL became 20 mm, embryo volume 2 cm(3), after which it increased linearly. Various ranges of relations are observed between FHR, obstetric, and hormonal measurements. The relationship between these parameters might be used for determination of abnormal growth and adverse outcomes in early pregnancy.

Determination of fetal heart rate from abdominal signals: evaluation of beat-to-beat accuracy in relation to the direct fetal electrocardiogram.

The main aim of our work was to assess the reliability of indirect abdominal electrocardiography as an alternative to the commonly used Doppler ultrasound monitoring technique. As a reference method, we used direct fetal electrocardiography. Direct and abdominal signals were acquired simultaneously, using dedicated instrumentation. The developed method of maternal signal suppression as well as fetal QRS complexes detection was presented. Recordings were collected during established labors, each consisted of four signals from the maternal abdomen and the reference signal acquired directly from the fetal head. After assessing the performance of the QRS detector, the accuracy of fetal heart rate measurement was evaluated. Additionally, to reduce the influence of inaccurately detected R-waves, some validation rules were proposed. The obtained results revealed that the indirect method is able to provide an accuracy sufficient for a reliable assessment of fetal heart rate variability. However, the method is very sensitive to recording conditions, influencing the quality of signals. Our investigations confirmed that abdominal electrocardiography, even in its current stage of development, offers an accuracy equal to or higher than an ultrasound method, at the same time providing some additional features.

697: Improved visual measurement of fetal heart rate (FHR) variability using an electronic ruler

697: Improved visual measurement of fetal heart rate (FHR) variability using an electronic ruler

Newborn Respiratory Disorders

Newborn Respiratory Disorders

Human fetal heart rate: a unique opportunity to assess the fetal programming hypothesis

AbstractThe study of the human fetus presents several unique challenges. Methods of the measurement and procedures for exploring the functional capability of the fetus coupled with the perceived fragility of the maternal/fetal dyad have been barriers for the study of the human fetus. The studies reported here by Kisilevesky and Hains (2009) and those conducted by others indicate that the psychology of the human fetus is not only important, but also clearly feasible. Kisilevsky and Hains (2009) provide compelling evidence from their own well‐designed studies and the growing number of studies from other investigators that by the middle of the second trimester the human fetus is able to detect ex utero stimulation and by the early third trimester can discriminate and learn associations. The review provides important technical information and physiological rationale for measuring human fetal heart rate as an index of cognition. Other measures of fetal behavior are only briefly discussed. Some, such as MEG and MRI are dismissed as impractical and only feasible near term. Other measures that can be used to assess fetal cognition, such as fetal movement and the elegant studies of fetal movement patterns Salisbury et al. (2005) are not discussed but see articles by Di Pietro, van den Bergh, James, Kawai, Sheridan et al., Huoutilainen, Hata et al. and Emory (this issue). This commentary will focus on the application of the human fetal heart rate measures that both support and broaden the conclusions of Kisilevsky and Hains (2009). Copyright © 2010 John Wiley & Sons, Ltd.

Fetal distress evaluation using and analyzing the variables of antepartum computerized cardiotocography

In this study, we tried to establish cut-off values for more than one parameters of computerized cardiotocography (c CTG) in the prediction of fetal distress during labor, using a group of pregnant women with low-risk pregnancies. A retrospective study was performed. Data were collected from 167 patients for measurements of fetal heart rate (FHR) variables and perinatal outcome. Computerized CTG was performed with an Oxford Sonicaid monitor with connection to a 8000 system for CTG spontaneous analysis. The following c CTG variables were considered: FHR, number of accelerations, the presence and the number of episodes of high and low variation, the number of decelerations, short-term variation (STV), peaks of contractions (per hour) and fetal movements assessed by maternal perception (per hour). Computerized CTG recordings started not earlier than the beginning of week 38 of gestation. Immediately after delivery, blood sample was collected from umbilical artery for umbilical artery blood gas analysis (UBGA). The main UBGA parameter in cord umbilical artery that was considered for analysis was pH. pH values<7.25 were considered as suspicious for acidemia and pH values>or=7.25 as normal. Women suspicious for fetal distress during labor presented significantly lower fetal movements (P=0.026), accelerations (P=0.018), variability (P<0.001), number of high episodes (P<0.001), higher values of FHR baseline (P<0.001) and low episodes (P<0.001). Only the number of decelerations did not differ significantly between the two groups (P=0.545). The cut-off points of 5.00 for STV and 3.00 for high episodes were determined to classify women with fetal distress, which yielded high sensitivities (34 and 52%) and specificities (96.6 and 94.9%), with positive predictive values of 81.0 and 81.3% and negative predictive values of 77.4 and 82.2%, respectively. In conclusion, we believe that not only STV but also other components of the cCTG, mainly the presence and the number of episodes of high variation, are related to pregnancy's outcome as measured by an umbilical artery pH.

The assessment of the gestational sac diameter, crown–rump length, progesterone and fetal heart rate measurements at the 10th gestational week to predict the spontaneous abortion risk

The assessment of the first trimester ultrasonographic and progesterone measurements to predict spontaneous abortion risk. Ninety-nine women at the 10th week of pregnancy were included in this prospective study. Their ages, progesterone (P) levels, mean gestational sac diameters (MGSD), crown-rump lengths (CRL), MGSD-CRL measurements and fetal heart rates (FHR) were recorded. These variables were compared by abortion status. Patients were followed up until the 20th weeks, and 8 (8.08%) aborted. We evaluated the variables by receiver operator characteristic curve to predict abortion. Only the areas under the curve for P levels (0.29) and for MGSD--CRL (0.16) were statistically significant We. also made logistic regression analysis to predict abortion. P level and FHR were statistically significant (P < 0.01) when the threshold value was 50%. Negative predictive value of the model was 98.9%, and positive predictive value was 50%. Overall, this model can correctly classify 94.9% of the groups. We determined threshold values for MGSD-CRL (> or =10 mm) and P (> or =25 ng/mL) to predict abortion, but not for FHR. Interestingly, 14 patients with FHR > or =175 beats/min did not abort. For the MGSD-CRL threshold, we can predict that the pregnancy will continue with 95.78% probability, with 67% sensitivity and 89% specificity. For the P threshold, the pregnancy will continue with 97.85% probability, with 80% sensitivity and 80% specificity. MGSD-CRL and P could predict patients with low abortion risk. However, at the 10th week of pregnancy, FHR > or =175 beats/min should be evaluated for this purpose by future studies with larger sample sizes.

Fetal electrocardiography: feasibility of long‐term fetal heart rate recordings

The feasibility and accuracy of long-term transabdominal fetal electrocardiogram (fECG) recordings throughout pregnancy were studied using a portable fECG monitor. Fifteen-hour recordings of fetal heart rate (FHR) were performed in 150 pregnant women at 20-40 weeks of gestation and 1-hour recordings were performed in 22 women in labour and compared with simultaneous scalp electrode recordings. When >or=60% of fECG signals was present, the recording was defined as good. Eighty-two percent (123/150) of antenatal recordings were of good quality. This percentage increased to 90.7 (136/150 recordings) when only the night part (11 p.m.-7 a.m.) was considered. Transabdominal measurement of FHR and its variability correlated well with scalp electrode recordings (r=0.99, P<0.01; r=0.79, P<0.01, respectively). We demonstrated the feasibility and accuracy of long-term transabdominal fECG monitoring.

Fetal Heart Rate Response to Maternal Hypocapnia and Hypercapnia in Late Gestation

ObjectiveTo examine the effects of acute maternal hypocapnia and hypercapnia on electronic fetal heart rate (FHR) patterns in late gestation. MethodsThirty-five women with healthy singleton pregnancies performed a modified carbon dioxide (CO2) rebreathing procedure between 34 and 38 weeks of pregnancy. Prior to rebreathing, subjects hyperventilated for five minutes to reduce end-tidal CO2 tensions (PETco2) below 23 Torr (hypocapnia). During rebreathing, PETco2 progressively increased from hypocapnia to hypercapnia (PETTco2 = 40–60 Torr) at a constant hyperoxic end-tidal O2 tension of 150 Torr. FHR responses were classified using standardized guidelines over four periods: 20 minutes before rebreathing (pretest), during hypocapnia and hypercapnia, and 20 minutes after rebreathing (post-test). ResultsMean baseline FHR measures (SD) over the four test periods were 138(8), 144(10), 132(11), and 137(9) beats per minute (bpm). All pairwise comparisons were statistically significant except the pretest versus post-test comparison (P < 0.05, Tukey-Kramer multiple comparisons test). A single tachycardia episode of 170 bpm was recorded in the post-test period. In 20 subjects FHR variability changed from moderate in the pretest period to minimal during hypocapnia and/or hypercapnia. All but two returned to moderate FHR variability in the post-test period. One other fetus with minimal post-test variability had moderate values in the three preceding test periods. ConclusionElectronic FHR parameters remained within normal limits for third-trimester fetuses with the exception of one fetus that experienced tachycardia. Acute maternal hypocapnia and hypercapnia over the range studied had no adverse effects on fetal well-being. These results support the safety of the modified CO2 rebreathing procedure for research in healthy, low-risk pregnancy.

Generalized Blind Delayed Source Separation Model for Online Non-invasive Twin-fetal Sound Separation: A Phantom Study

The fetal phonocardiogram, which is the acoustic recording of mechanical activity of the fetal heart, facilitates the measurement of the instantaneous fetal heart rate, beat-to-beat differences and duration of systolic and diastolic phases. These measures are sensitive indicators of cardiac function, reflecting fetal well-being. This paper provides an algorithm to non-invasively estimate the phonocardiogram of an individual fetus in a multiple fetus pregnancy. A mixture of fetal phonocardiograms is modeled by a generalized pure delayed mixing model. Mutual independence of fetal phonocardiograms is assumed to apply blind source separation based techniques to extract the fetal phonocardiograms from their mixtures. The performance of the algorithm is verified through simulation results and on experimental data obtained from a phantom that is used to simulate a twin pregnancy.

The Normal Fetal Heart Rate Study: Analysis Plan

Recording of fetal heart rate via CTG monitoring has been routinely performed as an important part of antenatal and subpartum care for several decades. The current guidelines of the FIGO (ref1) recommend a normal range of the fetal heart rate from 110 to 150 bpm. However, there is no agreement in the medical community whether this is the correct range (ref2). We aim to address this question by computerized analysis (ref 3) of a high quality database (HQDb, ref 4) of about one billion electronically registered fetal heart rate measurements from about 10,000 pregnancies in three medical centres over seven years. In the present paper, we lay out a detailed analysis plan for this evidence-based project in the vein of the validation policy of the Sylvia Lawry Centre for Multiple Sclerosis Research (ref 5) with a split of the database into an exploratory part and a part reserved for validation. We will perform the analysis and the validation after publication of this plan in order to reduce the probability of publishing false positive research findings (ref 6-7).

The Normal Fetal Heart Rate Study: Analysis Plan

AbstractRecording of fetal heart rate via CTG monitoring has been routinely performed as an important part of antenatal and subpartum care for several decades. The current guidelines of the FIGO (ref1) recommend a normal range of the fetal heart rate from 110 to 150 bpm. However, there is no agreement in the medical community whether this is the correct range (ref2). We aim to address this question by computerized analysis (ref 3) of a high quality database (HQDb, ref 4) of about one billion electronically registered fetal heart rate measurements from about 10,000 pregnancies in three medical centres over seven years. In the present paper, we lay out a detailed analysis plan for this evidence-based project in the vein of the validation policy of the Sylvia Lawry Centre for Multiple Sclerosis Research (ref 5) with a split of the database into an exploratory part and a part reserved for validation. We will perform the analysis and the validation after publication of this plan in order to reduce the probability of publishing false positive research findings (ref 6-7).

The Normal Fetal Heart Rate Study: Analysis Plan

AbstractRecording of fetal heart rate via CTG monitoring has been routinely performed as an important part of antenatal and subpartum care for several decades. The current guidelines of the FIGO (ref1) recommend a normal range of the fetal heart rate from 110 to 150 bpm. However, there is no agreement in the medical community whether this is the correct range (ref2). We aim to address this question by computerized analysis (ref 3) of a high quality database (HQDb, ref 4) of about one billion electronically registered fetal heart rate measurements from about 10,000 pregnancies in three medical centres over seven years. In the present paper, we lay out a detailed analysis plan for this evidence-based project in the vein of the validation policy of the Sylvia Lawry Centre for Multiple Sclerosis Research (ref 5) with a split of the database into an exploratory part and a part reserved for validation. We will perform the analysis and the validation after publication of this plan in order to reduce the probability of publishing false positive research findings (ref 6-7).

Effects of Smoking and Fetal Hypokinesia in Early Pregnancy

The aim of this study was to perform qualitative and quantitative ultrasound (US) monitoring of fetal movement in early pregnancy (gestational weeks 10-20) as a component of fetal behavior in women smokers. The study included three groups of 20 pregnant women each: non-smokers (group 1), smokers of an average of 10 cigarettes daily (group 2), and smokers of an average of >20 cigarettes daily (chronic smokers; group 3). Two-dimensional US study was performed once during gestational weeks 10-20 by the then standard method of fetal movement monitoring: 1) quantitative measurement of global fetal movements qualitatively verified as brisk or sluggish; 2) quantitative measurement of isolated spontaneous head movements; 3) quantitative measurement of isolated spontaneous arm movements; 4) quantitative measurement of isolated spontaneous leg movements; and 5) M-mode measurement of fetal heart rate. The ratio of brisk to sluggish fetal movements was 82.8% to 17.2%, 79.01% to 20.98%, and 44.25% to 55.75% in groups 1, 2, and 3, respectively (p <0.001). The rate of isolated spontaneous head and arm movements and of the upper cerebral pattern (head and arm movements) was statistically significantly lower in group 3 as compared with groups 1 and 2 (p <0.001), whereas no statistical significance was recorded in isolated spontaneous leg movements (p >0.01). The rate of fetal tachycardia was also significant in group 3, whereas tachyarrhythmia was recorded in seven children born to group 3 mothers (p <0.001). The present study of the effect of chronic tobacco hypoxia on the components of fetal behavior revealed a positive correlation between global and isolated fetal hypokinesia of the upper cerebral pattern (p <0.001), fetal tachycardia, and tachyarrhythmia in the group of mothers who were chronic smokers (p <0.001).

Sonographic screening for trisomy 13 at 11 to 13 +6 weeks of gestation

The purpose of this study was to examine the sonographic features of trisomy 13 at 11 to 13(+6) weeks of gestation. This was a retrospective study that examined the features of trisomy 13 at the ultrasound scan at 11 to 13(+6) weeks of gestation, which in our center is performed for the measurement of crown-rump length, nuchal translucency thickness, and fetal heart rate and the examination for major defects. In the 181 fetuses with trisomy 13, there were holoprosencephaly, exomphalos, and/or megacystis in 92 fetuses (50.2%), fetal heart rate above the 95th percentile in 129 fetuses (71.3%), and nuchal translucency above the 95th percentile in 141 fetuses (77.9%). There was no significant association between nuchal translucency and fetal heart rate, and it was estimated that inclusion of fetal heart rate in nuchal translucency screening can improve the detection rate of trisomy 13 by approximately 5%. At the 11 to 13(+6)-week scan, the measurement of fetal nuchal translucency and fetal heart rate and fetal examination for holoprosencephaly, exomphalos, and megacystis can identify >90% of fetuses with trisomy 13.