Brain sparing effect in growth-restricted fetuses is associated with decreased cardiac acceleration and deceleration capacities: a case-control study

Does fetal growth restriction induce neuropathology within the developing brainstem?

Fetal growth restriction (FGR) is a complex obstetric issue describing a fetus that does not reach its genetic growth potential. The primary cause of FGR is placental dysfunction resulting in chronic fetal hypoxaemia, which in turn causes altered neurological, cardiovascular and respiratory development, some of which may be pathophysiological, particularly for neonatal life. The brainstem is the critical site of cardiovascular, respiratory and autonomic control, but there is little information describing how chronic hypoxaemia and the resulting FGR may affect brainstem neurodevelopment. This review provides an overview of the brainstem-specific consequences of acute and chronic hypoxia, and what is known in FGR. In addition, we discuss how brainstem structural alterations may impair functional control of the cardiovascular and respiratory systems. Finally, we highlight the clinical and translational findings of the potential roles of the brainstem in maintaining cardiorespiratory adaptation in the transition from fetal to neonatal life under normal conditions and in response to the pathological environment that arises during development in growth-restricted infants. This review emphasises the crucial role that the brainstem plays in mediating cardiovascular and respiratory responses during fetal and neonatal life. We assess whether chronic fetal hypoxaemia might alter structure and function of the brainstem, but this also serves to highlight knowledge gaps regarding FGR and brainstem development.

The effect of drip versus intermittent feeding on splanchnic oxygenation in preterm infants with intrauterine growth restriction: a prospective randomized trial

The main purpose of this study was to evaluate the impact of drip versus intermittent feeding on splanchnic oxygenation in preterm infants with intrauterine growth restriction. The second objective was to assess the relationship between fetal splanchnic circulation parameters and splanchnic oxygenation during the first week of life. A single-center, prospective, randomized study with 51 fetuses/infants was conducted. Fetal Doppler measurements including umbilical artery, middle cerebral artery, and superior mesenteric artery (SMA) were recorded in IUGR fetuses. After preterm delivery, the infants were randomly assigned to one of two feeding modalities: drip (3-h continuous) or intermittent (bolus in 10 min). Continuous regional splanchnic saturation (rSO₂S) monitoring was carried out during the first week of life, simultaneously with continuous oxygen arterial saturation (SaO₂) monitoring, and the infants' fractional oxygen extractions (FOE) were calculated. These parameters were evaluated as means on a daily basis for the first week of life, as well as pre-prandial and post-prandial measurements on the seventh day. Fetal Doppler flow velocimetry disturbances were present in 72.5% of the study cohort. The drip (26 infants) and intermittent (25 infants) groups were similar in demographic and clinical characteristics, as well as the prevalence of feeding intolerance and necrotizing enterocolitis. During the first week of life, there was no difference in daily mean rSO₂S and FOE values between the drip and intermittent groups, whereas unfed infants had mostly lower rSO₂S values. Pre-prandial and post-prandial rSO₂S values remained stable in both groups. Also, no association was detected between fetal splanchnic circulation parameters and neonatal splanchnic oxygenation. RSO₂S values were strongly correlated to gestational age and birth weight. During the whole week, except for the first 2 days, infants with umbilical catheters had significantly lower rSO₂S values than infants without.  Conclusion: Our data suggest that the key factor in splanchnic oxygenation is feeding, not the feeding modality. In addition, the umbilical vein catheter had a negative impact on splanchnic oxygenation.  Clinical Trial Registration: The Effect of Neonatal Feeding Modalities on Splanchnic Oxygenation, NCT05513495,  https://clinicaltrials.gov/ct2/results cond=&term=NCT05513495&cntry=TR&state=&city=&dist= . Retrospectively registered, date of registration: August 2022. What is Known: • It is known that preterm infants with IUGR are at increased risk of hypoxic-ischemic intestinal damage and impaired splanchnic oxygenation. What is New: • The key factor in splanchnic oxygenation of preterm infants with IUGR is feeding, not the feeding modality (drip or intermittent). • In addition, the umbilical vein catheter had a negative impact on splanchnic oxygenation.

Fetal growth restriction and stillbirth: Biomarkers for identifying at risk fetuses

Fetal growth restriction (FGR) is a major cause of stillbirth, prematurity and impaired neurodevelopment. Its etiology is multifactorial, but many cases are related to impaired placental development and dysfunction, with reduced nutrient and oxygen supply. The fetus has a remarkable ability to respond to hypoxic challenges and mounts protective adaptations to match growth to reduced nutrient availability. However, with progressive placental dysfunction, chronic hypoxia may progress to a level where fetus can no longer adapt, or there may be superimposed acute hypoxic events. Improving detection and effective monitoring of progression is critical for the management of complicated pregnancies to balance the risk of worsening fetal oxygen deprivation in utero, against the consequences of iatrogenic preterm birth. Current surveillance modalities include frequent fetal Doppler ultrasound, and fetal heart rate monitoring. However, nearly half of FGR cases are not detected in utero, and conventional surveillance does not prevent a high proportion of stillbirths. We review diagnostic challenges and limitations in current screening and monitoring practices and discuss potential ways to better identify FGR, and, critically, to identify the “tipping point” when a chronically hypoxic fetus is at risk of progressive acidosis and stillbirth.

Association of Corpus Callosum Development With Fetal Growth Restriction and Maternal Preeclampsia or Gestational Hypertension

IMPORTANCE

It remains unknown whether neurodevelopmental impairments are directly associated with the structural development of the brain in offspring with fetal growth restriction (FGR) and mothers with preeclampsia (PE) or gestational hypertension (GH).

OBJECTIVES

To assess whether fetal corpus callosum (CC) development differed among pregnancies with PE or GH with FGR, pregnancies with PE or GH without FGR, and normotensive pregnancies, particularly the severity of maternal disease and FGR, and to identify the association between adverse perinatal outcomes and structural development of the CC in fetuses with FGR in pregnancies with PE or GH.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective matched case-control study was conducted between January 1, 2014, and January 31, 2021, at Women's Hospital, Zhejiang University School of Medicine in Hangzhou, China. The participant group included cases of singleton pregnancies with PE or GH with FGR; the control groups included cases with PG or GH without FGR and cases with paired normotensive pregnancy.

EXPOSURES

Maternal PE or GH and FGR.

MAIN OUTCOMES AND MEASURES

The length, thickness, total area, subdivision areas, and apparent diffusion coefficient (ADC) values of fetal CC were measured on magnetic resonance imaging (MRI) and analyzed. The association between adverse perinatal outcomes and structural development of CC was further investigated.

RESULTS

A total of 56 pregnant individuals with singleton pregnancies and PE or GH and fetuses with FGR were enrolled (maternal median [IQR] age, 29.0 [26.0-34.0] years; mean [SD] gestational age at MRI, 33.6 [2.5] weeks). Significant patterns of decreased median (IQR) fetal CC length (0.4284 [0.4079-0.4470] mm vs 0.4614 [0.4461-0.4944] mm, P < .001, vs 0.4591 [0.4310-0.4927] mm, P < .001) and mean (SD) CC total area (1.0779 [0.1931] mm2 vs 1.1896 [0.1803] mm2, P = .001, vs 1.1438 [0.1935] mm2, P = .02), adjusted for the cephalic index, was observed in cases of PE or GH with FGR compared with cases without FGR and cases with normotensive pregnancy. The splenium region of fetal CC also exhibited the distinct alterations in macrostructural development (with FGR: 0.3149 [0.0697] mm2 vs without FGR: 0.3727 [0.0698] mm2, P < .001, vs normotensive pregnancies: 0.3565 [0.0763] mm2, P < .001) and microstructural development (median [IQR] ADC values: 1.47 [1.38-1.57] × 10-3 mm2/s vs 1.57 [1.53-1.63] × 10-3 mm2/s, P = .009, vs 1.63 [1.50-1.70] × 10-3 mm2/s, P < .001) in all groups. Furthermore, significant associations were found between structural abnormality of the splenium region and adverse perinatal outcomes in the PE or GH with FGR group (mean [SD] ADC value: 1.40 [0.07] × 10-3 mm2/s; P = .04).

CONCLUSIONS AND RELEVANCE

Results of this study suggest that, in fetuses with FGR in pregnancies with PE or GH, decreased structural development of the CC, predominantly the splenium region, may be significantly associated with a higher risk of adverse perinatal outcomes and may be regarded as an MRI-based biomarker for better prenatal counseling and early management decisions.

The relationship of foetal superior mesenteric artery blood flow and the time to first meconium passage in newborns with late-onset foetal growth restriction

This study aimed to assess the relationship between the foetal superior mesenteric artery (SMA) Doppler and the time to first meconium passage (FMP) in foetuses with late-onset foetal growth restriction. This single-centre, prospective, observational, cohort study included 57 patients with late-onset FGR. The newborn infants were divided into two groups: preterm (36.8%) and term (63.2%). The time to FMP of the infants was compared to the foetal SMA parameters obtained within a week before delivery. The median time to FMP was similar between two groups (p = .31). The SMA pulsatility index (PI) was higher in the preterm group (p < .01). There was no correlation between foetal SMA PI or resistance index and time to FMP. In late-onset FGR infants, our study found no association between SMA Doppler measurements and time to FMP. However, a significant difference was detected in SMA PI between preterm and term infants. Impact StatementWhat is already known in this subject? Foetal growth restriction (FGR) can affect splanchnic circulation of the foetus and this alteration can be associated with some disorders including necrotising enterocolitis.What do the results of this study add? Superior mesenteric artery (SMA) Doppler indices are not associated with first meconium passage in neonates with late-onset foetal growth restriction. The pulsatility index of SMA is significantly higher in foetuses delivered before term.What are the implications of these findings for clinical practice and/or further research? Further research should be conducted to investigate the relationship between foetal SMA Doppler indices and neonatal gastrointestinal morbidities in foetuses with early onset FGR with Doppler anomalies. These studies can shed light from the prenatal to the postnatal period, allowing clinicians to predict potential problems and take precautions.

Relationship Between Deceleration Morphology and Phase Rectified Signal Averaging-Based Parameters During Labor

During labor, uterine contractions trigger the response of the autonomic nervous system (ANS) of the fetus, producing sawtooth-like decelerations in the fetal heart rate (FHR) series. Under chronic hypoxia, ANS is known to regulate FHR differently with respect to healthy fetuses. In this study, we hypothesized that such different ANS regulation might also lead to a change in the FHR deceleration morphology. The hypothesis was tested in an animal model comprising nine normoxic and five chronically hypoxic fetuses that underwent a protocol of umbilical cord occlusions (UCOs). Deceleration morphologies in the fetal inter-beat time interval (FRR) series were modeled using a trapezoid with four parameters, i.e., baseline b, deceleration depth a, UCO response time τ u and recovery time τ r . Comparing normoxic and hypoxic sheep, we found a clear difference for τ u (24.8±9.4 vs. 39.8±9.7 s; p < 0.05), a (268.1±109.5 vs. 373.0±46.0 ms; p < 0.1) and Δτ = τ u - τ r (13.2±6.9 vs. 23.9±7.5 s; p < 0.05). Therefore, the animal model supported the hypothesis that hypoxic fetuses have a longer response time τ u and larger asymmetry Δτ as a response to UCOs. Assessing these morphological parameters during labor is challenging due to non-stationarity, phase desynchronization and noise. For this reason, in the second part of the study, we quantified whether acceleration capacity (AC), deceleration capacity (DC), and deceleration reserve (DR), computed through Phase-Rectified Signal Averaging (PRSA, known to be robust to noise), were correlated with the morphological parameters. DC, AC and DR were correlated with τ u , τ r and Δτ for a wide range of the PRSA parameter T (Pearson's correlation ρ > 0.8, p < 0.05). In conclusion, deceleration morphologies have been found to differ between normoxic and hypoxic sheep fetuses during UCOs. The same difference can be assessed through PRSA based parameters, further motivating future investigations on the translational potential of this methodology on human data.

An integrated approach based on advanced CTG parameters and Doppler measurements for late growth restriction management

Background

The clinical diagnosis of late Fetal Growth Restriction (FGR) involves the integration of Doppler ultrasound data and Fetal Heart Rate (FHR) monitoring through computer assisted computerized cardiotocography (cCTG). The aim of the study was to evaluate the diagnostic power of combined Doppler and cCTG parameters by contrasting late FGR –and healthy controls.

Methods

The study was conducted from January 2018 to May 2020. Only pregnant women who had the last Doppler measurement obtained within 1 week before delivery and cCTG performed within 24 h before delivery were included in the study. Two hundred forty-nine pregnant women fulfilling the inclusion criteria were enrolled in the study; 95 were confirmed as late FGR and 154 were included in the control group.

Results

Among the extracted cCTG parameters, Delta Index, Short Term Variability (STV), Long Term Variability (LTV), Acceleration and Deceleration Phase Rectified Slope (APRS, DPRS) values were lower in the late FGR participants compared to the control group. In the FGR cohort, Delta, STV, APRS, and DPRS were found different when stratifying by MCA_PI (MCA_PI <5th centile or > 5th centile). STV and DPRS were the only parameters to be found different when stratifying by (UA_PI >95th centile or UA_PI <95th centile). Additionally, we measured the predictive power of cCTG parameters toward the identification of associated Doppler measures using figures of merit extracted from ROC curves.

The AUC of ROC curves were accurate for STV (0,70), Delta (0,68), APRS (0,65) and DPRS (0,71) when UA_PI values were > 95th centile while, the accuracy attributable to the prediction of MCA_PI was 0.76, 0.77, 0.73, and 0.76 for STV, Delta, APRS, and DPRS, respectively.

An association of UA_PI>95th centile and MCA_PI<5th centile with higher risk for NICU admission, was observed, while CPR < 5th centile resulted not associated with any perinatal outcome. Values of STV, Delta, APRS, DPRS were significantly lower for FGR neonates admitted to NICU, compared with the uncomplicated FGR cohort.

Conclusions

The results of this study show the contribution of advanced cCTG parameters and fetal Doppler to the identification of late FGR and the association of those parameters with the risk for NICU admission.

Trial registration

Retrospectively registered.

Prelabor and intrapartum Doppler ultrasound to predict fetal compromise

According to current estimates, over 20% of the 4 million neonatal deaths occurring globally every year are related to intrapartum hypoxic complications that happen as a result of uterine contractions against a background of inadequate placental function. Most of such intrapartum complications occur among apparently uncomplicated term pregnancies. Available evidence suggests that current risk-assessment strategies do not adequately identify many of the fetuses vulnerable to periods of intermittent hypoxia that characterize human labor. In this review, we discuss the data available on Doppler ultrasound for the evaluation of placental function before and during labor in appropriately grown fetuses; we also discuss the current strategies for ultrasound-based risk stratification, the physiology of intrapartum compromise, and the potential future treatments to prevent fetal distress in labor and reduce perinatal complications related to birth asphyxia.

Cardiac function in fetal growth restriction

Fetal growth restriction (FGR) is defined as the inability of the fetus to reach its growth potential. According to the onset of the disease is defined early (<32 weeks) or late (≥32 weeks). FGR is associated with an increased risk of adverse short- and long-term outcomes, including hypoxemic events and neurodevelopmental delay compared to normally grown fetuses and increased risk of complications in the infanthood and adulthood. The underlying cause of FGR is placental insufficiency leading to chronic fetal hypoxia that affects cardiac hemodynamic with different mechanism in early and late onset growth restriction. In early onset FGR adaptive mechanisms involve the diversion of the cardiac output preferentially in favor of the brain and the heart, while abnormal arterial and venous flow manifest in the case of further worsening of fetal hypoxia. In late FGR the fetal heart shows a remodeling of its shape and function mainly related to a reduction of umbilical vein flow. In this review we discuss the modifications occurring at the level of the fetal cardiac hemodynamic in fetuses with early and late FGR.

Intrapartum Doppler ultrasound: where are we now?

Intrapartum hypoxic events most commonly occur in low-risk pregnancies with appropriately grown fetuses. Continuous intrapartum monitoring by means of cardiotocography has not demonstrated a reduction in the frequency of adverse perinatal outcome but has been linked with an increase in the caesarean section rate, particularly among women considered at low risk. Available data from the literature suggests that abnormalities in the uterine artery Doppler and in the ratio between fetal cerebral and umbilical Doppler (i.e. cerebroplacental ratio [CPR]) are associated with conditions of subclinical placental function occurring in fetuses who have failed to achieve their growth potential regardless of their actual size. In this review we summarize the available evidence on the use of intrapartum Doppler ultrasound for the fetal surveillance during labor and the identification of the fetuses at risk of intrapartum distress.

Deceleration area and capacity during labour-like umbilical cord occlusions identify evolving hypotension: a controlled study in fetal sheep

OBJECTIVE

Cardiotocography is widely used to assess fetal well-being during labour. The positive predictive value of current clinical algorithms to identify hypoxia-ischaemia is poor. In experimental studies, fetal hypotension is the strongest predictor of hypoxic-ischaemic injury. Cohort studies suggest that deceleration area and deceleration capacity of the fetal heart rate trace correlate with fetal acidaemia, but it is not known whether they are indices of fetal arterial hypotension.

DESIGN

Prospective, controlled study.

SETTING

Laboratory.

SAMPLE

Near-term fetal sheep.

METHODS

One minute of complete umbilical cord occlusions (UCOs) every 5 minutes (1:5 min, n = 6) or every 2.5 minutes (1:2.5 min, n = 12) for 4 hours or until fetal mean arterial blood pressure fell <20 mmHg.

MAIN OUTCOME MEASURES

Deceleration area and capacity during the UCO series were related to evolving hypotension.

RESULTS

The 1:5 min group developed only mild metabolic acidaemia, without hypotension. By contrast, 10/12 fetuses in the 1:2.5-min group progressively developed severe metabolic acidaemia and hypotension, reaching 16.8 ± 0.9 mmHg after 71.2 ± 6.7 UCOs. Deceleration area and capacity remained unchanged throughout the UCO series in the 1:5-min group, but progressively increased in the 1:2.5-min group. The severity of hypotension was closely correlated with both deceleration area (P < 0.001, R²  = 0.66, n = 18) and capacity (P < 0.001, R²  = 0.67, n = 18). Deceleration area and capacity predicted development of hypotension at a median of 103 and 123 minutes before the final occlusion, respectively.

CONCLUSIONS

Both deceleration area and capacity were strongly associated with developing fetal hypotension, supporting their potential to improve identification of fetuses at risk of hypotension leading to hypoxic-ischaemic injury during labour.

TWEETABLE ABSTRACT

Deceleration area and capacity of fetal heart rate identify developing hypotension during labour-like hypoxia.

Exposures influencing the developing central autonomic nervous system

Autonomic nervous system function is critical for transition from in-utero to ex-utero life and is associated with neurodevelopmental and neuropsychiatric outcomes later in life. Adverse prenatal and neonatal conditions and exposures can impair or alter ANS development and, as a result, may also impact long-term neurodevelopmental outcomes. The objective of this article is to provide a broad overview of the impact of factors that are known to influence autonomic development during the fetal and early neonatal period, including maternal mood and stress during and after pregnancy, fetal growth restriction, congenital heart disease, toxic exposures, and preterm birth. We touch briefly on the typical development of the ANS, then delve into both in-utero and ex-utero maternal and fetal factors that may impact developmental trajectory of the ANS and, thus, have implications in transition and in long-term developmental outcomes. While many types of exposures and conditions have been shown to impact development of the autonomic nervous system, there is still much to be learned about the mechanisms underlying these influences. In the future, more advanced neuromonitoring tools will be required to better understand autonomic development and its influence on long-term neurodevelopmental and neuropsychological function, especially during the fetal period.

Assessment of BOLD response in the fetal lung

OBJECTIVE

Assessment of lung development and maturity is of utmost importance in prenatal counseling. Blood oxygen level-dependent (BOLD) effect MRI was developed for functional evaluations of organs. To date, no data are available in fetal lungs and nothing is known about the existence of a BOLD effect in the lungs. The aim of our study was to evaluate if a BOLD response could be detected in fetal lungs.

MATERIALS AND METHODS

From January 2014 to December 2016, 38 healthy pregnant women were prospectively enrolled. After a routine scan on a 1.5-T MRI device (normoxic period), maternal hyperoxia was induced for 5 min before the BOLD sequence (hyperoxic period). R2* was evaluated by fitting average intensity of the signal, both for normoxic (norm) and hyperoxic (hyper) periods.

RESULTS

A significant BOLD response was observed after maternal hyperoxia in the lungs with a mean R2* decrease of 12.1 ± 2.5% (p < 0.001), in line with the placenta response with a mean R2* decrease of 19.2 ± 5.9% (p < 0.0001), confirming appropriate oxygen uptake. Conversely, no significant BOLD effect was observed for the brain nor the liver with a mean ∆R2* of 3.6 ± 3.1% (p = 0.64) and 2.8 ± 3.7% (p = 0.23).

CONCLUSION

This study shows for the first time in human that a BOLD response can be observed in the normal fetal lung despite its prenatal "non-functional status." If confirmed in congenital lung and chest malformations, this property could be used in addition to the lung volume for a better prediction of postnatal respiratory status.

KEY POINTS

• Blood oxygen level-dependent (BOLD) effect MRI was developed for functional evaluations of organs and could have interesting implications for the fetal organs. • Assessment of lung development is of utmost importance in prenatal counseling, but to date no data are available in fetal lungs. • BOLD response can be observed in the normal fetal lung opening the way to studies on fetus with pathological lungs.

Cerebral oxygenation reflects fetal development in preterm monochorionic and dichorionic twins

BACKGROUND

Cerebral oxygenation (crSO₂) monitoring is increasingly used in high-risk infants. Monochorionic twins suffer from specific fetal pathologies that can affect cerebral hemodynamics. Limited data are available on crSO₂ and blood flow patterns in this population after birth.

OBJECTIVE

To evaluate crSO₂ changes in preterm monochorionic and dichorionic twins during the first 72 h of life.

METHODS

Near-infrared spectroscopy was used to measure crSO₂ in 62 infants from 31 twin pregnancies <32 weeks of gestation. The study group was divided into 4 subgroups: donor (1) and recipient (2) monochorionic twins (with twin-twin transfusion syndrome), fetal growth restriction (FGR) infants (3) and twins without fetal compromise (4).

RESULTS

There was significant difference in birth weight (p < 0.001) among 4 subgroups. We observed significant variation in crSO₂ among the subgroups using mixed model analysis (p < 0.001). The recipient twins exhibited the lowest crSO₂ (mean ± SE) throughout the study period (76 ± 0.3%), whereas the FGR and donor twins presented with the highest values (86 ± 0.3% and 83 ± 0.4% respectively). We found no statistically significant differences in neonatal mortality and morbidity among subgroups.

CONCLUSION

Our study revealed significant correlation between crSO₂ values postnatally and underlying fetal pathology in monochorionic and dichorionic preterm twins.

Intrapartum PRSA: a new method to predict fetal acidosis?-a case-control study

PURPOSE

Phase-rectified signal averaging method (PRSA) represents an analysis method which applied on fetal cardiotocography (CTG) allows the quantification of the speed of fetal heart rate changes. By calculating the average deceleration capacity (ADC) an assessment of the fetal autonomic nervous system (ANS) is possible. The objective of this study was to test its ability to predict perinatal acidosis.

METHODS

A case-control study was performed at a University Hospital in Munich. All intrapartum CTG heart rate tracings saved during a 7-year period were considered for analysis. All neonates born with an umbilical arterial blood pH ≤ 7.10 were considered as cases. Controls were defined as healthy fetuses born with a pH ≥ 7.25. The main matching criteria were gestational age at delivery, parity, birth mode, and birth weight percentile. Exclusion criteria were a planned caesarean section, fetal malformations, and multiple pregnancies. ADC and STV were then calculated during the last 60, the last 45, and the last 30 min intervals prior to delivery.

RESULTS

Of all stored birth CTG recordings, 227 cases met the inclusion criteria and were studied. ADC was significantly higher in fetuses born with acidemia (4.85 bpm ± 3.0) compared to controls (3.36 bpm ± 2.2). The area under ROC curve was 0.659 (95% CI 0.608-0.710) for ADC and 0.566 (0.512-0.620) for STV (p = 0.013).

CONCLUSIONS

This study confirms that the assessment of ADC using PRSA represents a good additional tool for the prediction of acute fetal acidosis during delivery.

Theoretical Value of Deceleration Capacity Points to Deceleration Reserve of Fetal Heart Rate

OBJECTIVE

The interpretation of Average Acceleration and Deceleration Capacities (AC/DC), computed through Phase-Rectified Signal Averaging (PRSA), in intrapartum fetal heart rate (FHR) monitoring is still matter of investigation. We aimed to elucidate some behaviors of AC/DC.

METHODS

We derived the theoretical value of PRSA for stationary stochastic Gaussian processes and proved that for these time series AC and DC are necessarily identical in absolute value. The difference between DC and AC, termed Deceleration Reserve (DR), was introduced to detect signal's asymmetric trends. DR was tested on FHR signals from: near-term pregnant sheep model of labor consisting of chronically hypoxic and normoxic fetuses with both groups developing acidemia due to umbilical cord occlusions (UCO); and the CTU-UHB dataset containing fetal CTG recordings collected during labor of newborns that resulted acidotic and non-acidotic, respectively. DR was compared with AC and DC in terms of discriminatory power (AUC), between the groups, after correcting for signal power or deceleration area, respectively.

RESULTS

DR displayed higher discriminatory power on the animal model during severe acidemia, with respect to AC/DC ( ) but also distinguished correctly all chronically hypoxic from normoxic fetuses at baseline prior to UCO. DR also outperformed AC/DC on the CTU-UHB dataset in distinguishing acidemic fetuses at birth (AUC: 0.65).

CONCLUSION

Theoretical results motivated the introduction of DR, that proved to be superior than AC/DC for risk stratification during labor.

SIGNIFICANCE

DR, measured during labor, might permit to distinguish acidemic fetuses due to their different autonomic regulation, paving the way for new monitoring strategies.

Multiscale Coupling of Uterine Electromyography and Fetal Heart Rate as a Novel Indicator of Fetal Neural Development

Fetal nerve maturation is a dynamic process, which is reflected in fetal movement and fetal heart rate (FHR) patterns. Classical FHR variability (fHRV) indices cannot fully reflect their complex interrelationship. This study aims to provide an alternative insight for fetal neural development by using the coupling analysis of uterine electromyography (UEMG) and FHR acceleration. We investigated 39 normal pregnancies with appropriate for gestational age (AGA) and 19 high-risk pregnancies with small for gestational age (SGA) at 28-39 weeks. The UEMG and FHR were recorded simultaneously by a trans-abdominal device during the night (10 p.m.-8 a.m.). Cross-wavelet analysis was used to characterize the dynamic relationship between FHR and UEMG. Subsequently, a UEMG-FHR coupling index (UFCI) was extracted from the multiscale coupling power spectrum. We examined the gestational-age dependency of UFCI by linear/quadratic regression models, and the ability to screen for SGA using binary logistic regression. Also, the performances of classical fHRV indices, including short-term variation (STV), averaged acceleration capacity (AAC), and averaged deceleration capacity (ADC), time- and frequency- domain indices, and multiscale entropy (MSE), were compared as references on the same recordings. The results showed that UFCI provided a stronger age predicting value with R² = 0.480, in contrast to the best value among other fHRV indices with R² = 0.335, by univariate regression models. Also, UFCI achieved superior performance for predicting SGA with the area under the curve (AUC) of 0.88, compared with 0.79 for best performance of other fHRV indices. The present results indicate that UFCI provides new information for early detection and comprehensive interpretation of intrauterine growth restriction in prenatal diagnosis, and helps improve the screening of SGA.

A systematic review on the utility of non-invasive electrophysiological assessment in evaluating for intra uterine growth restriction

Background

Non-invasive electrophysiological assessment (NIEA) is an evolving area in fetal surveillance and is attracting increasing research interest. There is however, limited data outlining its utility in evaluating intra uterine growth restriction (IUGR). The objective of this study was to carry out a systematic review to outline the utility of NIEA parameters in evaluating IUGR.

Methods

A systematic review of peer reviewed literature was performed, searching PUBMED, Ovid MEDLINE and EMBASE. The outcomes of interest included NIEA parameters [P wave duration, PR interval, QRS duration, QT interval, T/QRS ratio, short term variability (STV) and long term variability (LTV)] and a descriptive summary of relevant studies as well.

Results

Sixteen studies were identified as suitable for inclusion. The utility of NIEA parameters were investigated in tabular form. In particular, QRS and QT duration, T/QRS ratio, STV and PRSA analysis displayed utility and merit further consideration in evaluating for IUGR. Issues identified in the review were in relation to variances in definition of IUGR, small sample sizes and the lack of technological consistency across studies.

Conclusion

NIEA shows promise as an adjunct surveillance tool in fetal diagnostics for IUGR. Larger prospective studies should be directed towards establishing reliable parameters with a focus on uniformity of IUGR definition, technological consistency and the individualisation of NIEA parameters.

Electronic supplementary material

The online version of this article (10.1186/s12884-019-2357-9) contains supplementary material, which is available to authorized users.

Autonomic nervous system development and its impact on neuropsychiatric outcome

The central autonomic nervous system (ANS) is essential for maintaining cardiovascular and respiratory homeostasis in the newborn and has a critical role in supporting higher cortical functions. At birth, the central ANS is maturing and is vulnerable to adverse environmental and physiologic influences. Critical connections are formed early in development between the ANS and limbic system to integrate psychological and body responses. The Polyvagal Theory, developed by Stephen Porges, describes how modulation of the autonomic vagal impulse controls social responses and that a broad range of neuropsychiatric disorders may be due to impaired vagal balance, with either deficient vagal tone or excessive vagal reactivity. Under additional circumstances of prematurity, growth restriction, and environmental stress in the fetus and newborn, the immature ANS may undergo "dysmaturation". Maternal stress and health as well as the intrauterine environment are also quite important and have been implicated in causing ANS changes in the infant and neuropsychiatric diseases in children. This review will cover the aspects of ANS development and maturation that have been associated with neuropsychiatric disorders in children.

The Critical Role of the Central Autonomic Nervous System in Fetal-Neonatal Transition

The objective of this article is to understand the complex role of the central autonomic nervous system in normal and complicated fetal-neonatal transition and how autonomic nervous system dysfunction can lead to brain injury. The central autonomic nervous system supports coordinated fetal transitional cardiovascular, respiratory, and endocrine responses to provide safe transition of the fetus at delivery. Fetal and maternal medical and environmental exposures can disrupt normal maturation of the autonomic nervous system in utero, cause dysfunction, and complicate fetal-neonatal transition. Brain injury may both be caused by autonomic nervous system failure and contribute directly to autonomic nervous system dysfunction in the fetus and newborn. The central autonomic nervous system has multiple roles in supporting transition of the fetus. Future studies should aim to improve real-time monitoring of fetal autonomic nervous system function and in supporting typical autonomic nervous system development even under complicated conditions.

Influence of gestational diabetes on fetal autonomic nervous system: a study using phase-rectified signal-averaging analysis

OBJECTIVES

Maternal gestational diabetes mellitus (GDM) is known to influence fetal physiology. Phase-rectified signal averaging (PRSA) is an innovative signal-processing technique that can be used to investigate fetal heart signals. The PRSA-calculated variables average acceleration capacity (AAC) and average deceleration capacity (ADC) are established indices of autonomic nervous system (ANS) function. The aim of this study was to evaluate the influence of GDM on the fetal cardiovascular and ANS function in human pregnancy using PRSA.

METHODS

This was a prospective clinical case-control study of 58 mothers with diagnosed GDM and 58 gestational-age matched healthy controls in the third trimester of pregnancy. Fetal cardiotocography (CTG) recordings were performed in all cases at entry to the study, and a follow-up recording was performed in 19 GDM cases close to delivery. The AAC and ADC indices were calculated by the PRSA method and fetal heart rate short-term variation (STV) by CTG software according to Dawes-Redman criteria.

RESULTS

Mean gestational age of both groups at study entry was 35.7 weeks. There was a significant difference in mean AAC (1.97 ± 0.33 bpm vs 2.42 ± 0.57 bpm; P < 0.001) and ADC (1.94 ± 0.32 bpm vs 2.28 ± 0.46 bpm; P < 0.001) between controls and fetuses of diabetic mothers. This difference could not be demonstrated using standard computerized fetal CTG analysis of STV (controls, 10.8 ± 3.0 ms vs GDM group, 11.3 ± 2.5 ms; P = 0.32). Longitudinal fetal heart rate measurements in a subgroup of women with diabetes were not significantly different from those at study entry.

CONCLUSIONS

Our findings show increased ANS activity in fetuses of diabetic mothers in late gestation. Analysis of human fetal cardiovascular and ANS function by PRSA may offer improved surveillance over conventional techniques linking GDM pregnancy to future cardiovascular dysfunction in the offspring. Copyright © 2017 ISUOG. Published by John Wiley & Sons Ltd.

Non-invasive biomarkers of fetal brain development reflecting prenatal stress: An integrative multi-scale multi-species perspective on data collection and analysis

Prenatal stress (PS) impacts early postnatal behavioural and cognitive development. This process of 'fetal programming' is mediated by the effects of the prenatal experience on the developing hypothalamic-pituitary-adrenal (HPA) axis and autonomic nervous system (ANS). We derive a multi-scale multi-species approach to devising preclinical and clinical studies to identify early non-invasively available pre- and postnatal biomarkers of PS. The multiple scales include brain epigenome, metabolome, microbiome and the ANS activity gauged via an array of advanced non-invasively obtainable properties of fetal heart rate fluctuations. The proposed framework has the potential to reveal mechanistic links between maternal stress during pregnancy and changes across these physiological scales. Such biomarkers may hence be useful as early and non-invasive predictors of neurodevelopmental trajectories influenced by the PS as well as follow-up indicators of success of therapeutic interventions to correct such altered neurodevelopmental trajectories. PS studies must be conducted on multiple scales derived from concerted observations in multiple animal models and human cohorts performed in an interactive and iterative manner and deploying machine learning for data synthesis, identification and validation of the best non-invasive detection and follow-up biomarkers, a prerequisite for designing effective therapeutic interventions.

A Comprehensive Evaluation of the Predictive Abilities of Fetal Electrocardiogram-Derived Parameters during Labor in Newborn Acidemia: Our Institutional Experience

This study aimed to identify cardiotocography patterns that discriminate fetal acidemia newborns by comprehensively evaluating the parameters obtained from Holter monitoring during delivery. Between June 1, 2015, and August 1, 2016, a prospective observational study of 85 patients was conducted using fetal Holter monitoring at the Beijing Obstetrics and Gynecology Hospital, Capital Medical University, China. Umbilical cord blood was sampled immediately after delivery and fetal acidemia was defined as umbilical cord arterial blood pH < 7.20. Fetal electrocardiogram- (FECG-) derived parameters, including basal fetal heart rate (BFHR), short-term variation (STV), large acceleration (LA), deceleration capacity (DC), acceleration capacity (AC), proportion of episodes of high variation (PEHV), and proportion of episodes of low variation (PELV), were compared between 16 fetuses with acidemia and 47 without. The areas under the curve (AUC) of receiver operating characteristics (ROC) were calculated. Although all the computerized parameters showed predictive values for acidemia (all AUC > 0.50), STV (AUC = 0.84, P < 0.001), DC (AUC = 0.84, P < 0.001), AC (AUC = 0.80, P < 0.001), and PELV (AUC = 0.71, P = 0.012) were more strongly associated with fetal acidemia. Our institutional experience suggests that FECG-derived parameters from Holter monitoring are beneficial in reducing the incidence of neonatal acidemia.

Evaluation of Abdominal Fetal Electrocardiography in Early Intrauterine Growth Restriction

Objectives: This descriptive study was performed to evaluate the capability of a non-invasive transabdominal electrocardiographic system to extract clear fetal electrocardiographic (FECG) measurements from intrauterine growth restricted (IUGR) fetuses and to assess whether abdominal FECG parameters can be developed as markers for evaluating the fetal cardiac status in IUGR.

Methods: Transabdominal FECG was attempted in 20 controls and 15 IUGR singleton pregnancies at 20+0−33+6 weeks gestation. Standard ECG parameters were compared between the study groups and evaluated for their correlation. Accuracy for the prediction of IUGR by cut off values of the different FECG parameters was also determined.

Results: Clear P-QRST complexes were recognized in all cases. In the IUGR fetuses, the QT and QTc intervals were significantly prolonged (p = 0.017 and p = 0.002, respectively). There was no correlation between ECG parameters and Doppler or other indices to predict IUGR. The generation of cut off values for detecting IUGR showed increasing sensitivities but decreasing specificities with the prolongation of ECG parameters.

Conclusion: The study of fetal electrocardiophysiology is now feasible through a non-invasive transabdominal route. This study confirms the potential of FECG as a clinical screening tool to aid diagnosis and management of fetuses after key limitations are addressed. In the case of IUGR, both QT and QTc intervals were significantly prolonged and thus validate earlier study findings where both these parameters were found to be markers of diastolic dysfunction. This research is a useful prelude to a test of accuracy and Receiver Operating Characteristics (ROC) study.

[A prenatal ultrasound study of cerebral sulci and gyrus development in fetuses with tetralogy of Fallot]

OBJECTIVE

To evaluate the development of the cerebral sulci and gyrus and cerebral blood flow in fetuses with tetralogy of Fallot (ToF) in the second and third trimesters using ultrasound imaging.

METHODS

Forty fetuses (23-33⁺⁶ weeks) with ToF diagnosed using ultrasound imaging between December, 2015 and September, 2016 were analyzed in this study. The development of the cerebral sulci and gyrus was evaluated by measuring the parietal-occipital fissure (POF) depth, POF angle, sylvian fissure (SF) depth, SF width, uncovered insular width, calcarine fissure (CF) depth, hemisphere depth on the views of POF, SF and CF, uncovered insular ratio, biparietal diameter (BPD), and head circumference (HC). Cerebral hemodynamics were assessed by measuring the umbilical artery resistance index, umbilical artery pulsation index, middle cerebral artery pulsation index (MCA-PI), middle cerebral artery resistance index, the cerebral-to-placental resistance ratio, and the cerebroplacental ratio.

RESULTS

In ToF fetuses, the POF depth, SF depth, CF depth, BPD, HC and hemisphere depth on the views of parietal-occipital sulcus and calcarine sulcus were significantly smaller than those in the control group (P<0.05). The middle cerebral artery resistance index, middle cerebral artery pulsation index, the cerebral-to-placental resistance ratio and the cerebroplacental ratio were also significantly lower in ToF fetuses than in the control group (P<0.05).

CONCLUSION

The cerebral sulci and gyrus in ToF fetuses in second and third trimesters show underdevelopment compared with those in normal fetuses, and the changes in hemodynamics caused by abnormal cardiac structure might be one of the reasons for cerebral sulci and gyrus underdevelopment in fetuses with ToF.

Small-for-gestational-age babies of low-risk term pregnancies: does antenatal detection matter?

OBJECTIVES

To compare delivery route and admission rate to neonatal intensive care unit between small- and appropriate-for-gestational-age babies among low-risk term pregnancies.

METHODS

A retrospective study was conducted using the database of deliveries in 2014 at a tertiary hospital. Babies delivered at ≥37 weeks with birthweight <10th centile were considered small-for-gestational-age (SGA) and >90th centile were considered large-for-gestational-age. Fetal weight estimation at 30-33 weeks ultrasound <10th centile was considered antenatal detection of SGA.

RESULTS

Among 1429 low-risk term pregnancies, 11% (151/1429) had SGA babies and 5% (75/1429) had large-for-gestational-age. SGA babies were associated with higher rate of cesarean sections for nonreassuring fetal status (18/151 versus 8/1202, p < .001) and higher rate of admissions to neonatal intensive care unit (16/151 versus 18/1202, p < .001) compared to appropriate-for-gestational-age. Within SGA group, antepartum detected fetuses were associated with lower rate of operative deliveries for nonreassuring fetal status than undetected group (3/31 versus 39/120, p = .01) Conclusions: In our series, women with SGA term babies were associated with more adverse obstetric and neonatal outcome than appropriate-for-gestational age, especially among those undetected prenatally.

Longitudinal progression of fetal short-term variation and average acceleration and deceleration capacity after antenatal maternal betamethasone application

OBJECTIVE

To analyze the effect of maternal betamethasone given for fetal lung maturation on fetal short-term variation (STV) and average acceleration and deceleration capacity (AAC/ADC). Both of these factors are calculated by phase-rectified signal averaging (PRSA) and represent new parameters to assess the fetal autonomic nervous system.

STUDY DESIGN

A longitudinal prospective study including 26 pregnant women at risk for preterm delivery was performed. Two injections of 12mg betamethasone were administered intramuscularly at a 24h interval for lung maturation. Cardiotocography recordings were performed at defined time intervals: day 0 (before the first injection) and days 1, 2, 4 after the first corticosteroid administration. AAC/ADC and STV were calculated.

RESULTS

An increase of all parameters (STV, AAC and ADC) was documented between day 0 and day 1. Between day 1 and day 2, all three indices were significantly reduced (p<0.05). STV declined by 19.8%, AAC by 10.1% and ADC by 14.8%. A normalization of these values was seen after 96h.

CONCLUSION

Similar to STV, AAC/ADC shows significant changes after maternal betamethasone administration. The corticosteroid-induced transient decrease of the levels needs to be taken into account in the assessment of the fetal status to avoid misinterpretation of these parameters.