Magnetographic assessment of fetal hiccups and their effect on fetal heart rhythm

Prenatal diagnosis of fetal intraabdominal extralobar pulmonary sequestration: a 12-year 3-center experience in China

To provide useful information for diagnosing and predicting fetal intraabdominal extralobar pulmonary sequestration (IEPS), a retrospective review of diagnostic approaches was conducted. Ultrasonography was performed serially in 21 fetuses with IEPS from 2005 to 2017. Prenatal sonographic features, treatment, and outcomes of each case were evaluated and collected. These cases of IEPS were also compared to 43 cases previously reported by other researchers from 1986 to 2017. Of the 21 sonographic features, 14 (67%) were hyperechoic, 21 (100%) were well circumscribed, and 17 (81%) depicted a mass that shifted with fetal breaths/hiccups non-synchronized with adjacent organs (sliding sign). Feeding arteries were detected prenatally in 18 patients (86%). The lesion volume was 10.17 ± 4.66 cm³, the congenital cystic adenomatoid malformation volume ratio and cardiothoracic ratio were in normal range. The gestational age at diagnosis, location and echotexture of the lesion, and rate of surgical treatment were similar to previous studies, but with a significantly higher rate of detected feeding arteries (P < 0.01), and associated anomalies (P < 0.01). All infants who underwent surgery after birth had satisfactory outcomes. The sliding sign and feeding artery are essential features of IEPS in prenatal diagnosis.

Alterations in maternally perceived fetal movement and their association with late stillbirth: findings from the Midland and North of England stillbirth case-control study

OBJECTIVE

To report perception of fetal movements in women who experienced a stillbirth compared with controls at a similar gestation with a live birth.

DESIGN

Case-control study.

SETTING

41 maternity units in the UK.

PARTICIPANTS

Cases were women who had a late stillbirth ≥28 weeks gestation (n=291) and controls were women with an ongoing pregnancy at the time of the interview (n=733). Controls were frequency matched to cases by obstetric unit and gestational age.

METHODS

Data were collected using an interviewer-administered questionnaire which included questions on maternal perception of fetal movement (frequency, strength, increased and decreased movements and hiccups) in the 2 weeks before the interview/stillbirth. Five fetal movement patterns were identified incorporating the changes in strength and frequency in the last 2 weeks by combining groups of similar pattern and risk. Multivariable analysis adjusted for known confounders.

PRIMARY OUTCOME MEASURE

Association of maternally perceived fetal movements in relation to late stillbirth.

RESULTS

In multivariable analyses, women who reported increased strength of movements in the last 2 weeks had decreased risk of late stillbirth compared with those whose movements were unchanged (adjusted OR (aOR) 0.18, 95% CI 0.13 to 0.26). Women with decreased frequency (without increase in strength) of fetal movements were at increased risk (aOR 4.51, 95% CI 2.38 to 8.55). Daily perception of fetal hiccups was protective (aOR 0.31, 95% CI 0.17 to 0.56).

CONCLUSIONS

Increased strength of fetal movements and fetal hiccups is associated with decreased risk of stillbirth. Alterations in frequency of fetal movements are important in identifying pregnancies at increased risk of stillbirth, with the greatest risk in women noting a reduction in fetal activity. Clinical guidance should be updated to reflect that increase in strength and frequency of fetal movements is associated with the lowest risk of stillbirth, and that decreased fetal movements are associated with stillbirth.

TRIAL REGISTRATION NUMBER

NCT02025530.

Effects of Exercise During Pregnancy on Maternal Heart Rate and Heart Rate Variability

BACKGROUND

Pregnancy is associated with an increased sympathetic state, which can be exacerbated by gestational conditions. Research has shown that exercise during pregnancy lowers heart rate (HR) and can attenuate the symptoms of gestational conditions associated with increased sympathetic control. However, changes in maternal heart autonomic function in response to exercise have not been reported across multiple time points during pregnancy. This analysis is designed to address this gap.

OBJECTIVE

To determine if exercise throughout gestation improves maternal cardiac autonomic nervous system functioning, as evidenced by decreased HR and increased heart rate variability (HRV) indices.

DESIGN

Case control study.

SETTING

Academic medical institution.

PARTICIPANTS

A total of 56 women with healthy, singleton, low-risk pregnancies.

METHODS

Participants were asked to complete 3 resting 18-minute HRV recordings at 28, 32, and 36 weeks' gestation, along with a physical activity questionnaire.

MAIN OUTCOME MEASURES

HRV indices were calculated for time (R peak to R peak interval standard deviation and root mean squared of successive differences) and frequency (very low, low, and high frequency) domain measures. The differences between groups were compared for HRV indices at 28, 32, and 36 weeks.

RESULTS

Resting HR was significantly lower in the exercise group at 28 weeks (P < .01) compared with the control group. The exercise group had significantly (P < .05) increased measures of resting HRV time domain measures at 28, 32, and 36 weeks' gestation compared with the control group. Resting HRV power was significantly increased (P < .05) in all frequency domain measures at 32 weeks in the exercise group relative to the control group. No differences occurred in sympathovagal balance (low frequency/high frequency ratio) between groups.

CONCLUSION

Exercise throughout pregnancy can significantly improve cardiac autonomic control. More research is needed to determine if this adaptation to exercise may reduce the risk of adverse outcomes associated with gestational conditions with poor autonomic control, such as diabetes, hypertension, pre-eclampsia, and excessive weight gain.

Maternal physical activity mode and fetal heart outcome

BACKGROUND

Maternal leisure-time physical activity (LTPA) improves cardiac autonomic function in the fetus. The specific physical activity attributes (e.g., mode) that produce this benefit are not well understood.

AIM

To determine if more time spent performing non-continuous LTPA during pregnancy is significantly associated with lower fetal heart rate (HR) and increased heart rate variability (HRV).

STUDY DESIGN

This paper presents a retrospective analysis of previously reported data. Fetal magnetocardiograms (MCG) were recorded from 40 pregnant women at 36-wk gestational age.

OUTCOME MEASURES

Metrics of fetal HR and HRV, self-reported min of continuous and non-continuous LTPA performed during the 3-months preceding the 36-wk assessment point and covariates (maternal weight change pre to 36-wk, age, and resting HR and fetal activity state during MCG recordings.

RESULTS

Positive correlations were significant (p<0.05) between min of continuous LTPA, the time domain metrics that describe fetal overall HRV, short-term HRV and a frequency domain metric that reflects vagal activity. Time spent in non-continuous LTPA was positively correlated (p<0.05) with two HRV metrics that reflect fetal overall HRV. In the multiple regression analyses, minutes of non-continuous LTPA remained associated with fetal vagal activity (p<0.05) and the relationships between minutes of non-continuous LTPA and fetal overall HRV (p<0.005) persisted.

CONCLUSION

These data suggest non-continuous physical activity provides unique benefits to the fetal autonomic nervous system that may give the fetus an adaptive advantage. Further studies are needed to understand the physiological mechanisms and long-term health effects of physical activity (both non-continuous and continuous) performed during pregnancy to both women and their offspring.

Aerobic exercise during pregnancy influences infant heart rate variability at one month of age

BACKGROUND

Previously, we reported that regular maternal aerobic exercise during pregnancy was associated with lower fetal heart rate (HR) and higher heart rate variability (HRV) at 36weeks gestation. We now report the effect of maternal exercise on infant HR and HRV in subjects who remained active in the study at the one-month follow up visit.

AIMS

We aimed to determine whether differences in fetal cardiac autonomic control related to maternal physical activity were an in utero phenomenon or would persist 1month after birth.

STUDY DESIGN

Magnetocardiograms (MCGs) of infants born to regularly exercising (≥30min of aerobic activity, 3 times per week; N=16) and non-exercising (N=27) pregnant women were recorded using a fetal biomagnetometer. Normal R-peaks were marked to derive infant HR and HRV in time and frequency domains, including the root mean square of successive differences (RMSSD), the standard deviation of normal-to-normal interbeat intervals (SDNN), and power in the low frequency (LF) and high frequency (HF) bands. Group differences were examined with Student's t-tests.

RESULTS

Infants born to exercising women had significantly higher RMSSD (P=0.010), LF power (P=0.002), and HF power (P=0.004) than those born to women who did not engage in regular physical activity while pregnant.

CONCLUSION

Infants born to women who participated in regular physical activity during pregnancy continued to have higher HRV in the infant period. This suggests that the developing cardiac autonomic nervous system is sensitive to the effects of maternal physical activity and is a target for fetal programming.

Antenatal surveillance through estimates of the sources underlying the abdominal phonogram: a preliminary study

Today, it is generally accepted that current methods for biophysical antenatal surveillance do not facilitate a comprehensive and reliable assessment of foetal well-being and that continuing research into alternative methods is necessary to improve antenatal monitoring procedures. In our research, attention has been paid to the abdominal phonogram, a signal that is recorded by positioning an acoustic sensor on the maternal womb and contains valuable information about foetal status, but which is hidden by maternal and environmental sources. To recover such information, previous work has used single-channel independent component analysis (SCICA) on the abdominal phonogram and successfully retrieved estimates of the foetal phonocardiogram, the maternal phonocardiogram, the maternal respirogram and noise. The availability of these estimates made it possible for the current study to focus on their evaluation as sources for antenatal surveillance purposes. To this end, the foetal heart rate (FHR), the foetal heart sounds morphology, the maternal heart rate (MHR) and the maternal breathing rate (MBR) were collected from the estimates retrieved from a dataset of 25 abdominal phonograms. Next, these parameters were compared with reference values to quantify the significance of the physiological information extracted from the estimates. As a result, it has been seen that the instantaneous FHR, the instantaneous MHR and the MBR collected from the estimates consistently followed the trends given by the reference signals, which is a promising outcome for this preliminary study. Thus, as far as this study has gone, it can be said that the independent traces retrieved by SCICA from the abdominal phonogram are likely to become valuable sources of information for well-being surveillance, both foetal and maternal.

Effects of docosahexaenoic acid supplementation during pregnancy on fetal heart rate and variability: a randomized clinical trial

DHA (22:6n-3) supplementation during infancy has been associated with lower heart rate (HR) and improved neurobehavioral outcomes. We hypothesized that maternal DHA supplementation would improve fetal cardiac autonomic control and newborn neurobehavior. Pregnant women were randomized to 600 mg/day of DHA or placebo oil capsules at 14.4 (+/-4) weeks gestation. Fetal HR and HRV were calculated from magnetocardiograms (MCGs) at 24, 32 and 36 weeks gestational age (GA). Newborn neurobehavior was assessed using the Neonatal Behavioral Assessment Scale (NBAS). Post-partum maternal and infant red blood cell (RBC) DHA was significantly higher in the supplemented group as were metrics of fetal HRV and newborn neurobehavior in the autonomic and motor clusters. Higher HRV is associated with more responsive and flexible autonomic nervous system (ANS). Coupled with findings of improved autonomic and motor behavior, these data suggest that maternal DHA supplementation during pregnancy may impart an adaptive advantage to the fetus.

Cardiac vectors in the healthy human fetus: developmental changes assessed by magnetocardiography and realistic approximations of the volume conductor

This study sought to characterize the developmental changes of three measures used to describe the morphology of the fetal cardiac vector: QRS peak-amplitude, QRS duration and QRS time-amplitude integral. To achieve this objective, we rely on a recently developed methodology for fetal cardiac vector estimation, using multichannel fetal magnetocardiographic (fMCG) recordings and realistic approximations of the volume conductors obtained from free-hand ultrasound imaging. fMCG recordings and 3D ultrasound images were obtained from 23 healthy, uncomplicated pregnancies for a total of 77 recordings performed at gestational ages between 22 and 37 weeks. We report the developmental changes of the cardiac vector parameters with respect to gestational age and estimated fetal weight, as well as their dependence on the estimated ventricular mass derived from cardiac dimensions measured with M-mode ultrasound. The normative values can be used along with the cardiac time intervals reported by previous fMCG studies to assist future clinical studies investigating conditions that affect fetal cardiac function.

Fetal cardiac autonomic control during breathing and non-breathing epochs: the effect of maternal exercise

We explored whether maternal exercise during pregnancy moderates the effect of fetal breathing movements on fetal cardiac autonomic control assessed by metrics of heart rate (HR) and heart rate variability (HRV). Thirty women were assigned to Exercise or Control group (n=15/group) based on the modifiable physical activity questionnaire (MPAQ). Magnetocardiograms (MCG) were recorded using a dedicated fetal biomagnetometer. Periods of fetal breathing activity and apnea were identified using the fetal diaphragmatic magnetomyogram (dMMG) as a marker. MCG R-waves were marked. Metrics of fetal HR and HRV were compared using 1 breathing and 1 apneic epoch/fetus. The main effects of group (Exercise vs. Control) and condition (Apnea vs. Breathing) and their interactions were explored. Fetal breathing resulted in significantly lower fetal HR and higher vagally-mediated HRV. Maternal exercise resulted in significantly lower fetal HR, higher total HRV and vagally-mediated HRV with no difference in frequency band ratios. Significant interactions between maternal exercise and fetal breathing were found for metrics summarizing total HRV and a parasympathetic metric. Post hoc comparison showed no group difference during fetal apnea. Fetal breathing was associated with a loss of Total HRV in the Control group and no difference in the Exercise group. Both groups show enhanced vagal function during fetal breathing; greater in the Exercise group. During in utero breathing movements, the fetus of the exercising mother has enhanced cardiac autonomic function that may give the offspring an adaptive advantage.

On the interpretation of the independent components underlying the abdominal phonogram: a study of their physiological relevance

Recorded by positioning a sensitive acoustic sensor over the maternal womb, the abdominal phonogram is a signal that contains valuable information for foetal surveillance (e.g. heart rate), which is hidden by maternal and environmental sources. To recover such information, previous work used single-channel independent component analysis (SCICA) to separate the abdominal phonogram into statistically independent components (ICs) that, once acquired, must be objectively associated with the real sources underlying the abdominal phonogram-either physiological or environmental. This is a typical challenge for blind source separation methodologies and requires further research on the signals of interest to find a suitable solution. Here, we have conducted a joint study on 75 sets of ICs by means of statistical, spectral, complexity and time-structure analysis methods. As a result, valuable and consistent characteristics of the components separated from the abdominal phonogram by SCICA have been revealed: (1) the ICs are spectrally disjoint and sorted according to their frequency content, (2) only the ICs with lower frequency content present strong regular patterns and (3) such regular patterns are driven by well-known physiological processes given by the maternal breathing rate, the maternal heart rate and the foetal heart rate. This information was so promising that it has been used in current work for automatic classification of ICs and recovery of the traces of the physiological sources underlying the abdominal phonogram. Future work will look for the extraction of information useful for surveillance (e.g. heart rate), not only about foetal well-being, but also about maternal condition.

Maternal perception of fetal activity and late stillbirth risk: findings from the Auckland Stillbirth Study

BACKGROUND

  Maternal perception of decreased fetal movements has been associated with adverse pregnancy outcomes, including stillbirth. Little is known about other aspects of perceived fetal activity. The objective of this study was to explore the relationship between maternal perception of fetal activity and late stillbirth (≥28 wk gestation) risk.

METHODS

  Participants were women with a singleton, late stillbirth without congenital abnormality, born between July 2006 and June 2009 in Auckland, New Zealand. Two control women with ongoing pregnancies were randomly selected at the same gestation at which the stillbirth occurred. Detailed demographic and fetal movement data were collected by way of interview in the first few weeks after the stillbirth, or at the equivalent gestation for control women.

RESULTS

  A total of 155/215 (72%) women who experienced a stillbirth and 310/429 (72%) control group women consented to participate in the study. Maternal perception of increased strength and frequency of fetal movements, fetal hiccups, and frequent vigorous fetal activity were all associated with a reduced risk of late stillbirth. In contrast, perception of decreased strength of fetal movement was associated with a more than twofold increased risk of late stillbirth (aOR: 2.37; 95% CI: 1.29-4.35). A single episode of vigorous fetal activity was associated with an almost sevenfold increase in late stillbirth risk (aOR: 6.81; 95% CI: 3.01-15.41) compared with no unusually vigorous activity.

CONCLUSIONS

  Our study suggests that maternal perception of increasing fetal activity throughout the last 3 months of pregnancy is a sign of fetal well-being, whereas perception of reduced fetal movements is associated with increased risk of late stillbirth.

Characterization of the fetal diaphragmatic magnetomyogram and the effect of breathing movements on cardiac metrics of rate and variability

Breathing movements are one of the earliest fetal motor behaviors to emerge and are a hallmark of fetal well-being. Fetal respiratory sinus arrhythmia (RSA) has been documented but efforts to quantify the influence of breathing on heart rate (HR) and heart rate variability (HRV) are difficult due to the episodic nature of fetal breathing activity. We used a dedicated fetal biomagnetometer to acquire the magnetocardiogram (MCG) between 36 and 38 weeks gestational age (GA). We identified and characterized a waveform observed in the raw data and independent component decomposition that we attribute to fetal diaphragmatic movements during breathing episodes. RSA and increased high frequency power in a time-frequency analysis of the IBI time-series was observed during fetal breathing periods. Using the diaphragmatic magnetomyogram (dMMG) as a marker, we compared time and frequency domain metrics of heart rate and heart rate variability between breathing and non-breathing epochs. Fetal breathing activity resulted in significantly lower HR, increased high frequency power, greater sympathovagal balance, increased short-term HRV and greater parasympathetic input relative to non-breathing episodes confirming the specificity of fetal breathing movements on parasympathetic cardiac influence. No significant differences between breathing and non-breathing epochs were found in two metrics reflecting total HRV or very low, low and intermediate frequency bands. Using the fetal dMMG as a marker, biomagnetometry can help to elucidate the electrophysiologic mechanisms associated with diaphragmatic motor function and may be used to study the longitudinal development of human fetal cardiac autonomic control and breathing activity.

Indices and detectors for fetal MCG actography

Several recent studies have demonstrated the usefulness of fetal magnetocardiogram (fMCG) actography, a relatively new method of detecting fetal movement that can be performed in conjunction with fMCG assessment of fetal heart rate and rhythm. In this study, we formulate indices of fetal activity that incorporate information from all channels to achieve improved sensitivity. We also utilize statistical detection to provide an objective means of inferring significant fetal activity.

Aerobic exercise during pregnancy influences fetal cardiac autonomic control of heart rate and heart rate variability

BACKGROUND

Previous studies using ultrasound technology showed that fetal heart rate (HR) may be responsive to maternal aerobic exercise. Although it is recognized that cardiac autonomic control may be influenced by the intrauterine environment, little is known about how maternal exercise affects fetal heart development.

AIMS

This study tested the hypothesis that regular maternal exercise throughout gestation influences fetal cardiac autonomic control of HR and heart rate variability (HRV) when compared to fetuses of non-exercising women.

STUDY DESIGN

Magnetocardiograms (MCGs) were recorded using a dedicated fetal biomagnetometer at 28, 32 and 36 weeks gestational age (GA) from 26 regularly exercising (>30 min of aerobic exercise, 3x per week) and 35 healthy, non-exercising pregnant women. Fetal MCG was isolated and normal R-peaks were marked to derive fetal HR and HRV in the time and frequency domains. We applied a mixed-effects model to investigate the effects of exercise, GA and fetal activity state.

RESULTS

At 36 weeks GA, during the active fetal state, fetal HR was significantly lower in the exercise group (p=<0.0006). Post-hoc comparisons showed significantly increased HRV in the exercise group during the active fetal state at 36 weeks GA for both time and frequency domain measures.

CONCLUSION

These results indicate that regular maternal exercise throughout gestation results in significantly lower fetal HR and increased HRV.