PERFORMANCE OF A MATERNAL ABDOMINAL SURFACE ELECTRODE SYSTEM FOR FETAL HEART RATE AND UTERINE CONTRACTION MONITORING FROM 34-37 WEEKS

Objective: Compare performance of a maternal surface electrode patch with ultrasound- and tocodynamometer-based monitoring to detect fetal heart rate and uterine contractility in late preterm labors. Study design: Thirty women between 340/7 and 366/7 weeks’ gestation were monitored simultaneously with a Doppler/tocodynamometer system and a wireless fetal-maternal abdominal surface electrode system. Fetal and maternal heart rate and uterine contraction data from both systems were compared. Reliability was measured by the success rate and percent agreement. Deming regression and Bland-Altman analysis estimated the concordance between the systems. Uterine contractions were assessed by visual interpretation of monitor tracings. Results: The success rate for the surface electrode system was 89.5 (95% CI 85.7,93.3)% and for ultrasound 88.4 (84.9,91.9)%; p=0.73, with a percent agreement of 88.1 (84.2,92.8)%. Results were uninfluenced by the subjects’ body mass. The mean Deming slope was 1.0 and the y-intercept -3.0 bpm. Bland-Altman plots also showed a close relationship between the methods, with limits of agreement <10 bpm. The percent agreement for maternal heart rate was 98.2 (97.4,98.8)% and for uterine contraction detection was 89.5 (85.5,93.4)%. Conclusions: Fetal heart rate and uterine contraction monitoring at 34-366/7 weeks using abdominal surface electrodes was not inferior to Doppler ultrasound-tocodynamometry for fetal-maternal assessment. Registration: clinicaltrials.gov/February 20, 2017/ Identifier NCT03057275

Erroneous Recording of Maternal Heart Rate as Fetal Heart Rate During Second Stage of Labour: Isn’t it Time to Stop this?

Electronic Fetal Heart Rate (FHR) monitoring is recommended to assess fetal well-being during labour in high risk pregnancies. This Cardiotocograph (CTG) monitoring relies on the ultrasound technology with the limitation of signal loss in 15% to 40% of the cases [1]. In the earlier versions of these CTG monitors, fetal heart tracings were generally of reasonable quality with many artefacts and some degree of occasional large signal noise. Subsequent models were improved by signal modulation and autocorrelation. Although, these new methodologies of signal processing have reduced the signal loss, the issues of inadvertent monitoring of the maternal heart rate as fetal heart rate and inaccurate evaluations of baseline fetal heart rate (i.e. doubling or halving) continue to pose difficulties during intrapartum fetal heart rate monitoring.

Changes in Maternal Heart Rate Variability in Response to the Administration of Routine Obstetric Medication in Hospitalized Patients: Study Protocol for a Cohort Study (MAMA-Heart Study)

Pregnancy is a period of continuous change in the maternal cardiovascular system, partly mediated by the autonomic nervous system. Insufficient autonomic adaptation to increasing gestation is associated with pregnancy complications, such as hypertensive disorders of pregnancy and preterm birth (both major causes of perinatal morbidity and mortality). Consequently, maternal heart rate variability (mHRV), which is a proxy measure for autonomic activity, is increasingly assessed in these cohorts to investigate the pathophysiology of their complications. A better pathophysiological understanding could facilitate the early detection of these complications, which remains challenging. However, such studies (typically performed in pregnancies leading to hospitalization) have generated conflicting findings. A probable reason for these conflicting findings is that these study cohorts were likely administered routine obstetric medications during the study period of which the effects on mHRV are largely unknown. Subsequently, we design a longitudinal, observational study to quantifying the effect of these medications—particularly corticosteroids, which are known to affect fetal HRV—on mHRV to improve the interpretation of past and future studies. We will enroll 61 women admitted to a tertiary obstetric unit with an indication to receive corticosteroids antenatally. Participants’ mHRV will be continuously acquired throughout their hospitalization with wrist-worn photoplethysmography to facilitate a within-patient comparison of the effect of corticosteroids on mHRV.

Assessing Velocity and Directionality of Uterine Electrical Activity for Preterm Birth Prediction Using EHG Surface Records

The aim of the present study was to assess the capability of conduction velocity amplitudes and directions of propagation of electrohysterogram (EHG) waves to better distinguish between preterm and term EHG surface records. Using short-time cross-correlation between pairs of bipolar EHG signals (upper and lower, left and right), the conduction velocities and their directions were estimated using preterm and term EHG records of the publicly available Term–Preterm EHG DataSet with Tocogram (TPEHGT DS) and for different frequency bands below and above 1.0 Hz, where contractions and the influence of the maternal heart rate on the uterus, respectively, are expected. No significant or preferred continuous direction of propagation was found in any of the non-contraction (dummy) or contraction intervals; however, on average, a significantly lower percentage of velocity vectors was found in the vertical direction, and significantly higher in the horizontal direction, for preterm dummy intervals above 1.0 Hz. The newly defined features—the percentages of velocities in the vertical and horizontal directions, in combination with the sample entropy of the EHG signal recorded in the vertical direction, obtained from dummy intervals above 1.0 Hz—showed the highest classification accuracy of 86.8% (AUC=90.3%) in distinguishing between preterm and term EHG records of the TPEHGT DS.