Fetal Heart Rate Measurements Research Articles

Transcutaneous Discrimination of Fetal Heart Rate from Maternal Heart Rate: A Fetal Oximetry Proof-of-Concept.

Intrapartum care uses electronic fetal heart rate monitoring (EFHRM) for over 50years to indirectly assess fetal oxygenation. However, this approach has been associated with an increase in cesarean delivery rates and limited improvements in neonatal hypoxic outcome. To address these shortcomings, a novel transabdominal fetal pulse oximeter (TFO) is being developed to provide an objective measurement of fetal oxygenation. Previous studies have evaluated the performance of TFO on pregnant ewe. Building on the animal model, this study aims to determine whether TFO can successfully capture human fetal heart rate (FHR) signals during non-stress testing (NST) as a proof-of-concept. Eight ongoing pregnancies meeting specific inclusion criteria (18-40years old, singleton, and at least 36weeks' gestation) were enrolled with consent. Each study session was 15 to 20min long. Reference maternal heart rate (MHR) and FHR were obtained using finger pulse oximetry and cardiotocography for subsequent comparison. The overall root-mean-square error was 9.7BPM for FHR and 4.4 for MHR, while the overall mean-absolute error was 7.6BPM for FHR and 1.8 for MHR. Bland-Altman analysis displayed a mean bias ± standard deviation between TFO and reference of -3.9 ± 8.9BPM, with limits of agreement ranging from -21.4 to 13.6 BPM. Both maternal and fetal heart rate measurements obtained from TFO exhibited a p-value < 0.001, showing significant correlation with the reference. This proof-of-concept study successfully demonstrates that TFO can accurately differentiate maternal and fetal heart signals in human subjects. This achievement marks the initial step towards enabling fetal oxygen saturation measurement in humans using TFO.

Increased risk of preterm birth due to heat exposure during pregnancy: Exploring the mechanism of fetal physiology

BackgroundHeat exposure during pregnancy can increase the risk of preterm birth (PTB) through a range of potential mechanisms including pregnancy complications, hormone secretion and infections. However, current research mainly focuses on the effect of heat exposure on pathophysiological pathways of pregnant women, but ignore that maternal heat exposure can also cause physiological changes to the fetus, which will affect the risk of PTB. ObjectiveIn this study, we aimed to explore the mediating role of fetal heart rate (FHR) in the relationship between maternal heat exposure and PTB incidence. MethodsWe assigned heat exposure to a multi-center birth cohort in China during 2015–2018, which included all 162,407 singleton live births with several times FHR measurements during the second and third trimesters. We examined the associations between heat exposure, FHR and PTB in the entire pregnancy, each trimester and the last gestational month. The inverse odds ratio-weighted approach applied to the Cox regression was used to identify the mediation effect of heat exposure on PTB and its clinical subtypes via FHR. FindingsExposure to heat significantly increased the risk of PTB during the third trimester and the entire pregnancy, hazard ratios and 95 % CIs were 1.266 (1.161, 1.379) and 1.328 (1.218, 1.447). Heat exposure during the third trimester and entire pregnancy increased FHR in the third trimester by 0.24 bpm and 0.14 bpm. The proportion of heat exposure mediated by FHR elevation on PTB and its subtype ranged from 3.68 % to 24.06 %, with the significant mediation effect found for both medically indicated PTB and spontaneous PTB. ConclusionsThis study suggests that heat exposure during pregnancy has an important impact on fetal health, and FHR, as a surrogate marker of fetal physiology, may mediate the increased risk of PTB caused by extreme heat. Monitoring and managing physiological changes in the fetus would constitute a promising avenue to reduce adverse birth outcomes associated with maternal heat exposure.

A novel hybrid method for calculating the fetal heart rate from the non-invasive abdominal Electrocardiogram signal

Continuous monitoring of fetal health requires the accurate calculation of the Fetal Heart Rate (FHR) by efficiently isolating fetal Electrocardiogram (fECG) from non-invasive abdominal Electrocardiogram (aECG). There are numerous solutions proposed for this problem, having its own restrictions. This paper introduces a novel three-stage hybrid adaptive approach for fECG extraction and FHR determination from aECG. The proposed framework is an amalgamation of independent component analysis (ICA), adaptive exponential functional link network (AEFLN), and novel wavelet thresholding (NWT). The proposed work aims to determine the best quality fetal R-peaks for calculating fetal heart rate (FHR). ICA is a blind source separation technique that uses all the information from the multichannel inputs to determine the maternal Electrocardiogram (mECG) and enhanced aECG. In the next stage, a non-linear adaptive filter, AEFLN, is used for the extraction of fECG. This approach requires no additional algorithm for polarity reversal and time alignment before AEFLN. At last, NWT determines the fetal R-peak envelopes from the residual fECG. The R-peak envelopes are used to analyze FHR, and its accuracy was accessed using the FHR trace. So far, FastICA-AEFLN-NWT has not been used as a hybrid method for fECG extraction and fetal R-peak detection. The algorithm’s effectiveness was tested on both real databases from Daisy and Physionet and synthetic databases from Physionet. The proposed hybrid method attains 95.29 % of sensitivity (SE), 96.68 % of Positive Predictive Value (PPV), 95.92 % of F1 score, and FHR measurement (FHRmeas) is 29.72 bpm2. The proposed methodology outperforms the state-of-art methods in fECG extraction.

Pre-pregnancy BMI Association with Maternal Phenotype and Offspring Neurobehavioral Outcomes

BackgroundAllostatic load due to chronic exposure to physiological or psychological stressors lead to compromised capacity of the body to maintain homeostasis. Obesity as a metabolic stressor is associated with a suboptimal physiological milieu including an inflammatory state and a dysregulated stress axis. Perinatal maternal body mass index (BMI) impacts pregnancy, birth outcomes, and child metabolic and neurodevelopmental health. We examine the impacts of pre-pregnancy BMI on maternal phenotype characteristics throughout pregnancy and fetal heart rate measurements as an early marker of programming effects of altered autonomic nervous system and infant neurobehavioral outcomes with a focus on sex-dimorphic effects. MethodsPregnant women (n=176) attended sessions at gestation weeks 12-22, 23-28, and 34-36, where blood was collected for cytokine analysis and DNA methylation, and Edinburgh post-partum depression scale was administered. On the latter two visits, heart rate assessment was carried out for mothers and fetuses. ResultsMaternal high BMI was associated with higher perinatal depression, increased inflammation, and reduced heart rate variability. DNA methylation of maternal blood indicated enrichment in immune related biological processes. Moreover, we observed a decrease in fetal heart rate variability in female fetuses of women of high BMI, indicating alteration in the neurobehavioral development of the fetus. In infancy, female infants of high BMI mothers had reduced behavioral regulation and orientation to stimulus. ConclusionThis work highlights that the metabolic stress associated with BMI could leave a molecular fingerprint that could explain other maternal physiological and psychological outcomes, which in turn program the fetal neurodevelopmental outcomes.

Feasibility of Teaching Emergency Department Nurses to Determine Fetal Heart Rates Using Bedside Ultrasound Versus the Hand-Held Doppler

BackgroundThe current nursing standard for assessment of injured pregnant patients ≥12 weeks presenting to the emergency department (ED) includes obtaining an auditory fetal heart rate (FHR) measurement using a handheld Doppler (HHD). If the audible lower maternal heart rate is mistakenly determined as the FHR, the misidentified rate can cause false concern for fetal distress. PurposeA feasibility study was performed to investigate if nurses could accurately determine FHRs using point-of-care ultrasound (POCUS). MethodsNurses completed a self-paced learning module along with 2-hour hands-on simulation to determine FHRs using POCUS. Competency achievement was determined by ED physician clinical supervision on pregnant patients ≥8 weeks presenting to the ED between May 9 to November 29, 2022. FindingsEight of 11 nurses achieved competency. DiscussionThe participants had mixed reviews on using POCUS but favored POCUS over the HHD for reliability of locating and determining the FHR.

Computerised Cardiotocography Analysis for the Automated Detection of Fetal Compromise during Labour: A Review.

The measurement and analysis of fetal heart rate (FHR) and uterine contraction (UC) patterns, known as cardiotocography (CTG), is a key technology for detecting fetal compromise during labour. This technology is commonly used by clinicians to make decisions on the mode of delivery to minimise adverse outcomes. A range of computerised CTG analysis techniques have been proposed to overcome the limitations of manual clinician interpretation. While these automated techniques can potentially improve patient outcomes, their adoption into clinical practice remains limited. This review provides an overview of current FHR and UC monitoring technologies, public and private CTG datasets, pre-processing steps, and classification algorithms used in automated approaches for fetal compromise detection. It aims to highlight challenges inhibiting the translation of automated CTG analysis methods from research to clinical application and provide recommendations to overcome them.

Combining early pregnancy bleeding with ultrasound measurements to assess spontaneous abortion risk among infertile patients

Approximately 15% of all clinically recognized pregnancies in patients with infertility result in spontaneous abortion. However, despite its potential to have a profound and lasting effect on physical and emotional well-being, the natural history of spontaneous abortion in women with infertility has not been described. Although vaginal bleeding is a common symptom in pregnancies conceived via reproductive technologies, its prognostic value is not well understood. This study aimed to evaluate the combination of early pregnancy bleeding and first-trimester ultrasound measurements to determine spontaneous abortion risk. This was a retrospective cohort study of patients with infertility who underwent autologous embryo transfer resulting in singleton intrauterine pregnancy confirmed by ultrasound from January 1, 2017, to December 31, 2019. Early pregnancy symptoms of bleeding occurring before gestational week 8 and measurements of crown-rump length and fetal heart rate from ultrasounds performed during gestational week 6 (6 0/7 to 6 6/7 weeks of gestation) and gestational week 7 (7 0/7 to 7 6/7 weeks of gestation) were recorded. Modified Poisson regression with robust error variance was adjusted a priori for patient age, embryo transfer day, and transfer of a preimplantation genetic-tested embryo to estimate the relative risk and 95% confidence interval of spontaneous abortion for dichotomous variables. The relative risks and positive predictive values for early pregnancy bleeding combined with ultrasound measurements on the occurrence of spontaneous abortion were calculated for patients who had an ultrasound performed during gestational week 6 and separately for patients who had an ultrasound performed during gestational week 7. The primary outcome was spontaneous abortion in the setting of vaginal bleeding with normal ultrasound parameters. The secondary outcomes were spontaneous abortion with vaginal bleeding and (1) abnormal crown-rump length, (2) abnormal fetal heart rate, and (3) both abnormal crown-rump length and abnormal fetal heart rate. Of the 1858 patients who were included (359 cases resulted in abortions and 1499 resulted in live births), 315 patients (17.0%) reported vaginal bleeding. When combined with ultrasound measurements from gestational week 6, bleeding was significantly associated with increased spontaneous abortion only when accompanied by absent fetal heart rate (relative risk, 5.36; 95% confidence interval, 3.36-8.55) or both absent fetal heart rate and absent fetal pole (relative risk, 9.67; 95% confidence interval, 7.45-12.56). Similarly, when combined with ultrasound measurements from gestational week 7, bleeding was significantly associated with increased spontaneous abortion only when accompanied by an abnormal assessment of fetal heart rate or crown-rump length (relative risk, 5.09; 95% confidence interval, 1.83-14.19) or both fetal heart rate and crown-rump length (relative risk, 14.82; 95% confidence interval, 10.54-20.83). With normal ultrasound measurements, bleeding was not associated with increased spontaneous abortion risk (relative risk: 1.05 [95% confidence interval, 0.61-1.78] in gestational week 6 and 0.80 [95% confidence interval, 0.36-1.74] in gestational week 7), and the live birth rate was comparable with that in patients with normal ultrasound measurements and no bleeding. Patients with a history of infertility who present after embryo transfer with symptoms of vaginal bleeding should be evaluated with a pregnancy ultrasound to accurately assess spontaneous abortion risk. In the setting of normal ultrasound measurements, patients can be reassured that their risk of spontaneous abortion is not increased and that their live birth rate is not decreased.

Early recognition and management of maternal sepsis in Pakistan: a feasibility study of the implementation of FAST-M intervention

ObjectiveMaternal sepsis is the third leading cause of maternal mortality globally. WHO and collaborators developed a care bundle called FAST-M (Fluids, Antibiotics, Source identification and treatment, Transfer and Monitoring) for...

The Epigenetic Link of Perinatal BMI to Maternal Phenotype and Fetal Heart Rate

Obesity is a metabolic stressor associated with a suboptimal physiological milieu including an inflammatory state and a dysregulated stress axis. Perinatal maternal BMI impacts pregnancy and birth outcomes along with child metabolic and neurodevelopmental health that are believed to be mediated by epigenetic mechanisms. Our research examines the impacts of pre-pregnancy BMI in a cohort of healthy pregnancies (n=187); first, by characterizing maternal phenotype throughout pregnancy, including her stress physiology (diurnal salivary cortisol), inflammatory status (blood cytokine levels), perinatal depression (EPDS scores), and the underlying epigenetic signature (DNA methylation) in blood that could mediate these effects. Second, we examine the effects of pre-pregnancy BMI on fetal heart rate measurements as an early marker of programming effects of altered autonomic nervous system and the associated placental DNA methylation with a focus on sex-dimorphic effects. Finally, we explore the impact of increasing the allostatic load of high BMI with stress, which was phenotyped in women early in pregnancy driven by data with 27 variables assessing psychological and physical health, on differential placental DNA methylation. To date: regional analysis revealed about 4500 differentially methylated regions (DMR) overall in response to high BMI. Gene ontology enrichment analysis revealed that DM genes annotated to these DMRs were enriched for biological processes involving inflammation in males and RNA silencing in females. This work highlights that the metabolic stress associated with BMI could leave a molecular fingerprint that mediate other maternal physiological and psychological outcomes, which in turn program the fetal neurodevelopmental outcomes.

Evaluation of cyclic repetition frequency based algorithm for fetal heart rate extraction from fetal phonocardiography

The passive and non-invasive approach of fetal heart rate (FHR) estimation using fetal phonocardiography (fPCG) provides an alternative to the commonly used Doppler ultrasound-based technique. The acoustic signal recorded on the mother’s abdomen is corrupted by noise, making FHR estimation difficult. Thus, an accurate and reliable FHR measurement algorithm from the fPCG signal is needed. This study evaluates a cyclic repetition frequency-based algorithm with additional FHR validation steps on the clinical recordings from three datasets with varying signal quality. The FHR from the algorithms is compared against the reference FHR measurements, and the accuracy and reliability performance measure is determined. The cyclic repetition algorithm significantly improves (p < 0.05) against the Hilbert-envelope autocorrelation algorithm for poor-quality signals. The algorithm's average reliability across three datasets is 93%, and accuracy is 4.5 beats per minute. The algorithm performs well for the gestation week ranging from 26 −40 and for the labor and antenatal ward data.

Fast electro-plasmonic detection of heart signal in Balb/C cells onto one-dimensional plasmonic grating.

The heart is a vital and complex organ in the human body that forms with most organs between the second week of pregnancy, and fetal heart rate is an important indicator or biological index to know the condition of fetal well-being. In general, long-term measurement of fetal heart rate is the most widely used method of providing information about fetal health. In addition to fetal life, growth, and maturity, information such as congenital heart disease, often due to structural or functional defects in heart structure that often occur during the first trimester of pregnancy during fetal development, can be detected by continuous monitoring of fetal heart rate. The gold standard for monitoring the fetus's health is the use of non-invasive methods and portable devices so that while maintaining the health of the mother and fetus, it provides the possibility of continuous monitoring, especially for mothers who have a high-risk pregnancy. Therefore, the present study aimed to propose a low-cost, compact, and portable device for recording the heart rate of 18-day-old fetal mouse heart cells. Introduced device allows non-invasive heart rate monitoring instantly and without side effects for mouse fetal heart cells. One-dimensional gold-plated plasmonic specimens as a physiological signal recorder are mainly chips with nanoarray of resonant nanowire patterns perform in an integrated platform. Here the surface plasmon waves generated in a one-dimensional plasmonic sample are paired with an electrical wave from the heart pulse, and this two-wave pairing is used to record and detect the heart rate of fetal heart cells with high accuracy and good sensitivity. This measurement was performed in normal mode and two different stimulation modes. Stimulation of cells was performed once using adrenaline and again with electrical stimulation. Our results show that our sensor is sensitive enough to detect heart rate in both standard and excitatory states and is also well able to detect and distinguish between changes in heart rate caused by different excitatory conditions.

Automatic signal quality assessment of raw trans-abdominal biopotential recordings for non-invasive fetal electrocardiography.

Introduction: Wearable monitoring systems for non-invasive multi-channel fetal electrocardiography (fECG) can support fetal surveillance and diagnosis during pregnancy, thus enabling prompt treatment. In these embedded systems, power saving is the key to long-term monitoring. In this regard, the computational burden of signal processing methods implemented for the fECG extraction from the multi-channel trans-abdominal recordings plays a non-negligible role. In this work, a supervised machine-learning approach for the automatic selection of the most informative raw abdominal recordings in terms of fECG content, i.e., those potentially leading to good-quality, non-invasive fECG signals from a low number of channels, is presented and evaluated. Methods: For this purpose, several signal quality indexes from the scientific literature were adopted as features to train an ensemble tree classifier, which was asked to perform a binary classification between informative and non-informative abdominal channels. To reduce the dimensionality of the classification problem, and to improve the performance, a feature selection approach was also implemented for the identification of a subset of optimal features. 10336 5-s long signal segments derived from a real dataset of multi-channel trans-abdominal recordings acquired from 55 voluntary pregnant women between the 21st and the 27th week of gestation, with healthy fetuses, were adopted to train and test the classification approach in a stratified 10-time 10-fold cross-validation scheme. Abdominal recordings were firstly pre-processed and then labeled as informative or non-informative, according to the signal-to-noise ratio exhibited by the extracted fECG, thus producing a balanced dataset of bad and good quality abdominal channels. Results and Discussion: Classification performance revealed an accuracy above 86%, and more than 88% of those channels labeled as informative were correctly identified. Furthermore, by applying the proposed method to 50 annotated 24-channel recordings from the NInFEA dataset, a significant improvement was observed in fetal QRS detection when only the channels selected by the proposed approach were considered, compared with the use of all the available channels. As such, our findings support the hypothesis that performing a channel selection by looking directly at the raw abdominal signals, regardless of the fetal presentation, can produce a reliable measurement of fetal heart rate with a lower computational burden.

Accuracy, interpretability and usability study of a wireless self-guided fetal heartbeat monitor compared to cardiotocography

Fetal Cardiography is usually performed using in-hospital Cardiotocographic (CTG) devices to assess fetal wellbeing. New technologies may permit home-based, self-administered examinations. We compared the accuracy, clinical interpretability, and user experience of a patient-administered, wireless, fetal heartbeat monitor (HBM) designed for home use, to CTG. Initially, participants had paired HBM and CTG examinations performed in the clinic. Women then used the HBM unsupervised and rated the experience. Sixty-three women had paired clinic-based HBM and CTG recordings, providing 6982 fetal heart rate measures for point-to-point comparison from 126 min of continuous recording. The accuracy of the HBM was excellent, with limits of agreement (95%) for mean fetal heart rate (FHR) between 0.72 and −1.78 beats per minute. The FHR was detected on all occasions and confirmed to be different from the maternal heart rate. Both methods were equally interpretable by Obstetricians, and had similar signal loss ratios. Thirty-four (100%) women successfully detected the FHR and obtained clinically useful cardiographic data using the device at home unsupervised. They achieved the required length of recording required for non-stress test analysis. The monitor ranked in the 96–100th percentile for usability and learnability. The HBM is as accurate as gold-standard CTG, and provides equivalent clinical information enabling use in non-stress test analyses conducted outside of hospitals. It is usable by expectant mothers with minimal training.

Sistem Pengukuran Detak Jantung Janin Melalui Elektrokardiogram Abdominal dan Android

&lt;p class="Abstract"&gt;An android-based fetal heart rate measurement is presented in this article. The fetal heart rate was obtained from the mother's abdominal electrocardiogram which was then measured and processed by Raspberry pi using k-means. Raspberry pi processed results produce ECG signals and fetal heart rate which was displayed on Android devices in real-time. The android application can also save heart rate and ECG data or retrieve previously taken heart rate recordings. The system obtained that the average value of accuracy, sensitivity and predictive positive were 90.49%, 97.10% and 93.03%, respectively. The variation of the training time of the algorithm showed that the training time of 10 and 15 seconds mostly has better performance than the training time of 5 seconds.&lt;/p&gt;

Novel Method for Fetal and Maternal Heart Rate Measurements Using 2-D Ultrasound Color Doppler Flow Images.

Fetal heart rate (FHR) and maternal heart rate (MHR) are important indicators of fetal well-being during pregnancy. A common method in clinical examination is to estimate the FHR using the Doppler shift of echoes from umbilical artery blood flow based on an ultrasound pulsed-wave (PW) Doppler technique. Similarly, a sampling gate can be located at the maternal blood flow to measure MHR using PW Doppler. Ultrasound color Doppler flow imaging (CDFI) is one of the most commonly used imaging modes for clinical fetal examinations. Color coding is employed to display the blood flow velocity and direction in color grades according to the Doppler shift. Continuous CDF images contain dynamic changes characteristics of the blood flow. The periodic characteristics can be used to obtain heart rate information. Therefore, here we propose a novel method to measure FHR and MHR simultaneously using CDF images. The proposed method calculates the histogram of color similarity of CDF images to initially extract the periodic characteristics of the CDF image sequence. The histogram of color similarity function is then processed by a bandpass filter and autocorrelation operation to reduce noise and enhance periodicity. Finally, peak detection is performed on the processed signal to obtain the period and estimate the heart rate. The proposed method can measure the FHR and MHR in parallel after selecting two regions containing the umbilical artery and maternal blood flow, respectively. Thus, the method has high computational efficiency. The proposed method was evaluated on a Doppler flow phantom and clinical CDF images and then compared with the PW Doppler method. The correlation analysis and Bland-Altman plots reveal that the proposed method agrees well with the PW Doppler. It is a sanity check method for real-time clinical FHR and MHR measurements.

Fetal heartrate tracking system based on intensity of Doppler signal

Doppler-detected fetal heart rate (FHR) tracking is the primary testing method for assessing fetal well-being during antepartum care. However, owing to fetal movements or maternal position variations, the transducer on the abdomen can be displaced, changing the fetal heart location (FHL) and resulting in frequent signal losses and uninterpretable results. In this study, we present FHR monitoring system for continuously maintaining FHR measurements without specifying the location of the Doppler ultrasound transducer. An algorithm is developed to track the FHL based on the intensity of the received Doppler signal. The performance is evaluated by conducting underwater experiments using an object with repeated movements. The tracking error is 7.93° on the X-axis and 1.42° on the Y-axis. Even with those tracking errors, the FHR is continuously recorded. This system can be used to obtain heart rate records without manipulating the position of the transducer and losing the signal.

Heart rate estimation and validation algorithm for fetal phonocardiography

Objective. Fetal heart rate (FHR) is an important parameter for assessing fetal well-being and is usually measured by doppler ultrasound. Fetal phonocardiography can provide non-invasive, easy-to-use and passive alternative for fetal monitoring method if reliable FHR measurements can be made even in noisy clinical environments. Therefore, this work presents an automatic algorithm to determine FHR from the fetal heart sound recordings in a noisy clinical environment. Approach. Using an electronic stethoscope fetal heart sounds were recorded from the expecting mother’s abdomen, during weeks 30–40 of their pregnancy. Of these, 60 recordings were analyzed manually by two observers to obtain reference heart rate measurement. An algorithm was developed to determine FHR using envelope detection and autocorrelation of the signals. Algorithm performance was improved by implementing peak validation algorithm utilizing knowledge of valid FHR from prior windows and power spectral density function. The improvements in accuracy and reliability of algorithm were measured by mean absolute error (MAE) and positive percent agreement. Main results. By including the validation step, the MAE reduced from 11.50 to 7.54 beats per minute and positive percent agreement improved from 81% to 87%. Significance. We classified the recordings into good, moderate and poor quality to understand how the algorithm works in each of the case. The proposed algorithms provide good accuracy overall but are sensitive to the noises in recording environment that influence the quality of the signals.

A Realistic and Inexpensive Ultrasound Phantom for Teaching M-Mode Measurement of Fetal Heart Rate.

M-mode ultrasound is frequently used to measure a fetal heart rate. Phantoms are used to simulate clinical conditions for teaching ultrasound-related skills. This is particularly important in the case of early pregnancy, when it is not ethical to use a live fetus in utero for teaching purposes. To date, no phantom has been created to model the beating heart of an intrauterine pregnancy. Our goal was to create such a model for use in teaching M-mode ultrasound. The phantom is constructed using a toy fish, several balloons, and water-absorbing gel crystals. We have created a novel phantom for use in teaching M-mode measurements. The cost per phantom is around $20 and the phantom can be constructed in about 20 min. This phantom is easily constructed and cost-effective. It gives learners the opportunity to practice measuring an intrauterine fetal heart rate in a learning environment without exposing a live fetus to unnecessary ultrasound.

Ultrasound monitoring of pregnancy in mini-lop rabbits

Ultrasound plays a considerable role in human and animal reproduction in terms of early detection of pregnancy, prediction of parturition time, and diagnosis of fetal abnormalities. The present study aimed to evaluate the ultrasound implementation for monitoring of gestation in mini-lop rabbits. Fifteen heads of pubertal does were selected and kept in normal conditions of feeding and temperature. Animals were mated with three bucks from the same breed. The pregnancy monitoring was begun from five days post-mating (dpm) to kindling using a 12.5 MHz ultrasonic transducer. The examinations were performed at fixed dpm for all does (5, 7, 12, 16, 20, and 26). Furthermore, randomly selected does (2–3 does per day; one doe was fixed) were subjected to daily ultrasound examination to estimate the relationship between the ultrasound biometrics with the gestational age (GA) and days to parturition. The pregnancy rate was 80%, and the mean number of live kits at birth was 4.2 in the present study. Based on the ultrasound records, the gestation length can be divided into three tertiles of pregnancy (TOP) in rabbits. The first TOP (0–10 dpm) was monitored by detecting and measuring the gestational sac diameter from 6 to 10 dpm. The 2nd TOP (11–12 dpm) was characterized by detection and measurement of Crown Rump Length and Fetal Heart Rate. From 15 to 20 dpm, bi-parietal diameter and head circumference were positively correlated with the GA (p-value < 0.05). Abdominal circumference and femur length were detectable and measurable during the 3rd TOP (21 dpm-kindling). Pregnancy was detected as early as six dpm with acceptable markers in mini-lop rabbits. Highly significant negative correlations were detected between days to parturition and the sonographic biometrics. Three abnormal fetuses were successfully detected and described, too.

Moving object detection and tracking based on Doppler ultrasound

Fetal health monitoring during pregnancy has become a necessary procedure. Fetal heart rate (FHR) monitoring can determine fetal development or presence of heart disease and evaluate fetal well-being. The FHR measurement uses typically an acoustic probe-based Doppler ultrasound. Doppler ultrasound method transmits a continuous wave signal to the abdomen of a pregnant woman to receive a reflected signal from the fetal heart. Periodic displacement of the heart tissue produces the Doppler effect and the phase change of the reflected wave is proportional to the velocity of the fetal heart. The reflected signal is modulated into a phase signal and the received signal is demodulated to detect the heart rate. The current clinician system consists of a single probe and requires the probe to be manipulated to the optimal position to measure FHR. The system is highly dependent on trained diagnostic experts. The movement of the pregnant woman and the fetus leads to the misaligned acoustic beam which degrades the reliability of the measurement. This work presents a detection and tracking system using a Doppler signal to compensate for the target's movement. The system is implemented by integrating multi-channel probes interfaced to a Doppler signal converter with a 2-degree of freedom (DOF) motor device. This work describes the characteristics of two key components: Doppler signals of multi-channel probes according to the direction of the acoustic beam and the algorithm with a 2-DOF tracking system.