Vital signs monitoring is a fundamental component of ensuring the health and safety of women and newborns during pregnancy, labor, and childbirth. This monitoring is often the first step in early detection of pregnancy abnormalities, providing an opportunity for prompt, effective intervention to prevent maternal and neonatal morbidity and mortality. Contemporary pregnancy monitoring systems require numerous devices wired to large base units; at least five separate devices with distinct user interfaces are commonly used to detect uterine contractility, maternal blood oxygenation, temperature, heart rate, blood pressure, and fetal heart rate. Current monitoring technologies are expensive and complex with implementation challenges in low-resource settings where maternal morbidity and mortality is the greatest. We present an integrated monitoring platform leveraging advanced flexible electronics, wireless connectivity, and compatibility with a wide range of low-cost mobile devices. Three flexible, soft, and low-profile sensors offer comprehensive vital signs monitoring for both women and fetuses with time-synchronized operation, including advanced parameters such as continuous cuffless blood pressure, electrohysterography-derived uterine monitoring, and automated body position classification. Successful field trials of pregnant women between 25 and 41 wk of gestation in both high-resource settings (n = 91) and low-resource settings (n = 485) demonstrate the system's performance, usability, and safety.

https://www.pnas.org/content/pnas/118/20/e2100466118.full.pdf

Comprehensive pregnancy monitoring with a network of wireless, soft, and flexible sensors in high- and low-resource health settings.

Non-invasive fetal electrocardiogram (NIFECG) is an evolving technology in fetal surveillance which is attracting increasing research interest. There is however, only limited data outlining the reference ranges for normal cardiac time intervals (CTIs). The objective of our group was to carry out a systematic review to outline normal fetal CTIs using NIFECG. A systematic review of peer reviewed literature was performed, searching PUBMED,Ovid MEDLINE and EMBASE. The outcomes of interest included fetal CTIs (P wave duration, PR interval, QRS duration and QT interval) and a descriptive summary of relevant studies as well. The outcomes were grouped as early pre-term (≤ 32 weeks), moderate to late pre-term (32–37 weeks) and term (37–41 weeks). 8 studies were identified as suitable for inclusion. Reference ranges of CTIs were generated. Both PR interval and QRS duration demonstrated a linear correlation with advancing gestation. Several studies also demonstrated a reduction in signal acquisition between 27 and 32 weeks due to the attenuation by vernix caseosa. In this group, both the P wave and T waves were difficult to detect due to signal strength and interference. NIFECG demonstrates utility to quantify CTIs in the fetus, particularly at advanced gestations. Larger prospective studies should be directed towards establishing reliable CTIs across various gestations.

/pdf/a-systematic-review-of-cardiac-time-intervals-utilising-non-2vnbrumio4.pdf

A systematic review of cardiac time intervals utilising non-invasive fetal electrocardiogram in normal fetuses

Non-invasive fetal electrocardiography (ECG) is a promising method for evaluating fetal cardiac electrical activity. Despite advances in fetal ECG technology, its ability to provide reliable, interpretable results in a typical outpatient fetal cardiology setting remains unclear. We sought to determine the feasibility of measuring standard ECG intervals in an outpatient fetal cardiology practice using an abdominal fetal ECG device that employs blind source separation with reference, an innovative signal-processing technique for fetal ECG extraction. Women scheduled for clinically indicated outpatient fetal echocardiogram underwent 10 min of fetal ECG acquisition from the maternal abdomen using specialized gel electrodes. A bedside laptop computer performed fetal ECG extraction, allowing real-time visualization of fetal and maternal ECG signals. Offline post-processing of 1 min of recorded data yielded fetal P-wave duration, PR interval, QRS duration, RR interval, QT interval, and QTc. Fifty-five fetuses were studied with gestational age 18–37 weeks, including 13 with abnormal fetal echocardiogram findings and three sets of twins. Interpretable results were obtained in 91% of fetuses, including 85% during the vernix period and 100% of twin fetuses. PR interval and RR interval of 18–24 week gestation fetuses were significantly shorter than those with gestational age 25–31 and 32–37 weeks. Of the six fetuses with abnormal rhythms on fetal echocardiogram, fetal ECG tracing was interpretable in five and matched the rhythm noted on fetal echocardiogram. Abdominal fetal ECG acquisition is feasible for arrhythmia detection and ECG interval calculation in a routine clinical setting.

Feasibility of Non-invasive Fetal Electrocardiographic Interval Measurement in the Outpatient Clinical Setting

Fetal cardiac monitoring is one of the cornerstones of modern obstetric care. Noninvasive fetal electrocardiography (NI-FECG) is an emerging modality for monitoring fetal well-being using electrical signals recorded from the maternal abdomen. However, the reliability of NI-FECG extraction techniques remains highly variable due to a range of technical and clinical factors, such as sensor placement and interindividual anatomic variations. In this work, we propose, develop, and validate an open-source method for modeling these variations, including changes in maternal body structure and fetal position using two clinical NI-FECG databases. To validate our model’s accuracy, we first assess its performance in characterizing the fetal QRS (fQRS) complex amplitude in six private NI-FECG recordings with detailed anatomic information. To demonstrate its clinical utility, we next apply our model to predict an optimal sensor placement in a separate open-access database of 60 24-channel NI-FECG recordings. The optimal six sensor positions predicted by our model achieve similar reliability for fetal heart rate (FHR) monitoring compared to the entire 24-sensor array. The presented results indicate our model provides a suitable method for estimating the influence of anatomic variations on NI-FECG signals and optimizing sensor placement in a simulated setting. The code for the developed model has been made available under an open-source GPL license and contributed to the fecgsyn toolbox.

Personalized Anatomic Modeling for Noninvasive Fetal ECG: Methodology and Applications

One of the most successful achievements of fetal intervention is the pharmacologic management of fetal arrhythmias. This management usually takes place during the second or third trimester. While most arrhythmias in the fetus are benign, both tachy‐ and bradyarrhythmias can lead to fetal hydrops or cardiac dysfunction and require treatment under certain conditions. This review will highlight precise diagnosis by fetal echocardiography and magnetocardiography, the 2 primary means of diagnosing fetuses with arrhythmia. Additionally, transient or hidden arrhythmias such as bundle branch block, QT prolongation, and torsades de pointes, which can lead to cardiomyopathy and sudden unexplained death in the fetus, may also need pharmacologic treatment. The review will address the types of drug therapies; current knowledge of drug usage, efficacy, and precautions; and the transition to neonatal treatments when indicated. Finally, we will highlight new assessments, including the role of the nurse in the care of fetal arrhythmias. The prognosis for the human fetus with arrhythmias continues to improve as we expand our ability to provide intensive care unit–like monitoring, to better understand drug treatments, to optimize subsequent pregnancy monitoring, to effectively predict timing for delivery, and to follow up these conditions into the neonatal period and into childhood. Coordinated initiatives that facilitate clinical fetal research are needed to address gaps in knowledge and to facilitate fetal drug and device development.

Fetal Arrhythmia Diagnosis and Pharmacologic Management

Background Fetal electrocardiogram (fECG) can detect QRS signals in fetuses from as early as 17 weeks' gestation; however, the technique is limited by the minute size of the fetal signal relative to noise ratio. The aim of this study was to evaluate precise fetal cardiac time intervals (fCTIs) with the help of a newly developed fetal ECG device (Monica Healthcare System). Methods In a prospective manner we included 15-18 healthy fetuses per gestational week from 32 weeks onwards. The small and wearable Monica AN24 monitoring system uses standard ECG electrodes placed on the maternal abdomen to monitor fECG, maternal ECG and uterine electromyogram (EMG). Fetal CTIs were estimated on 1000 averaged fetal heart beats. Detection was deemed successful if there was a global signal loss of less than 30% and an analysis loss of the Monica AN24 signal separation analysis of less than 50%. Fetal CTIs were determined visually by three independent measurements. Results A total of 149 fECGs were performed. After applying the requirements 117 fECGs remained for CTI analysis. While the onset and termination of P-wave and QRS-complex could be easily identified in most ECG patterns (97% for P-wave, PQ and PR interval and 100% for QRS-complex), the T-wave was detectable in only 41% of the datasets. The CTI results were comparable to other available methods such as fetal magnetocardiography (fMCG). Conclusions Although limited and preclinical in its use, fECG (Monica Healthcare System) could be an additional useful tool to detect precise fCTIs from 32 weeks' gestational age onwards.

Maria Sewald

Papers

Fetal cardiac time intervals in healthy pregnancies - an observational study by fetal ECG (Monica Healthcare System).