Fetal Heart Rate Variability Research Articles

Preterm Brain Injury: Mechanisms and Challenges

Preterm fetuses and newborns have a high risk of neural injury and impaired neural maturation, leading to neurodevelopmental disability. Developing effective treatments is rather challenging, as preterm brain injury may occur at any time during pregnancy and postnatally, and many cases involve multiple pathogenic factors. This review examines research on how the preterm fetus responds to hypoxia-ischemia and how brain injury evolves after hypoxia-ischemia, offering windows of opportunity for treatment and insights into the mechanisms of injury during key phases. We highlight research showing that preterm fetuses can survive hypoxia-ischemia and continue development in utero with evolving brain injury. Early detection of fetal brain injury would provide an opportunity for treatments to reduce adverse neurodevelopmental outcomes, including cerebral palsy. However, this requires that we can detect injury using noninvasive methods. We discuss how circadian changes in fetal heart rate variability may offer utility as a biomarker for detecting injury and phases of injury.

Maternal depressed mood and serotonergic antidepressant treatment during pregnancy differentially shape the continuity between fetal–newborn neurobehaviour

BackgroundPrenatal serotonin reuptake inhibitor (SRI) antidepressant exposure is associated with newborn neurobehavioural disturbances, but it remains unclear whether this reflects a transient pharmacologic condition or an altered neurodevelopmental trajectory emerging in utero from sustained gestational SRI exposure. AimThis study explored longitudinal relationships between third-trimester fetal physiology and newborn neurobehaviour, and determined whether early neurobehavioural continuity is shaped by prenatal SRI or depression exposure. MethodsParticipants were 127 pregnant mothers and their fetal-newborn offspring. Four groups were defined based on antenatal depressive symptoms and SRI treatment: Control (n = 51), Depressed (unmedicated; n = 35), SRI-Depressed (n = 26) and SRI-Non-Depressed (n = 15). Doppler measures of fetal heart rate (fHR), motor activity and vascular hemodynamics were obtained at 36-weeks' gestation, then newborn neurobehavioural maturity was evaluated at postnatal day-7. Partial least squares analysis was used to identify latent correlations between fetal-newborn measures; associations were further studied with hierarchical regression testing group moderation. ResultsTwo dimensions described 74 % of the covariance between fetal physiologic and newborn neurobehavioural measures (permuted p < 0.05). Three latent fetal-newborn relationships were significantly moderated by group: (1) lower fHR variability, and (2) greater fHR decelerations, predicted lower alertness/orientation scores but only in SRI-Depressed-group newborns; and (3) lower fetal cerebrovascular resistance predicted lower motor scores in Depressed-group newborns. SRI treatment to euthymia was not associated with fetal-newborn neurobehavioural disturbances. ConclusionsMaternal depression, both unmedicated and SRI-treated with persistent/poorly-managed mood symptoms, differentially shaped fetal-newborn neurobehavioural continuity. These findings suggest that neurobehavioural disturbances may predate birth, and underscore the importance of effective mental health management during pregnancy.

How does fetal inflammatory response syndrome change fetalresponse to hypoxia? An experimental study in a fetal sheep model.

Fetal inflammatory response syndrome associated with acidosis during labor is a high-risk situation for the fetus. This study evaluated hemodynamic, gasometric, and heart rate variability changes during acute fetal inflammatory response syndrome associated with hypoxia, compared with isolated hypoxia. Acute fetal inflammatory response syndrome was obtained via anintravenously injection of lipopolysaccharide derived from Escherichia coli. Hypoxia was induced by repeated umbilical cord occlusions during three phases: mild, moderate, and severe umbilical cord occlusions. Two groups were created with chronically instrumented near-term fetal sheep: one group with isolated hypoxia, the other with hypoxia and fetal inflammatory response syndrome. Hemodynamic, gas parameters, and fetal heart rate variability were compared between the groups. The hypoxia and fetal inflammatory response syndrome group had a higher mortality rate (n = 4/9) compared with the hypoxia group (n = 0/9). Gasometric state was altered earlier in case of lipopolysaccharide injection (pH = 7.22 (7.12-7.24) vs 7.28 (7.23-7.34) p = 0.01; lactate = 10.3 mmol/L (9.4-11.0) vs 6.0 mmol/L (4.1-8.2) p < 0.001 after mild occlusions). After mild occlusions, the hypoxia and fetal inflammatory response syndrome group had higher values on seven heart rate variability parameters compared with the hypoxia group. After moderate occlusions, two parameters remained significantly higher. During fetal inflammatory response syndrome, fetal adaptation to hypoxia is impaired. In case of fetal infection, acidosis during labor is likely to become severe more rapidly, requiring closer fetal monitoring during labor.

A multimodal dual-branch fusion network for fetal hypoxia detection

Labor is the most severe test of a fetus’s ability to survive hypoxia. Even low-risk full-term fetuses may endure variable degrees of hypoxia as a result of intrapartum uterine contractions. It is imperative for clinicians to expeditiously identify fetal hypoxia and implement timely interventions. However, due to the intricacy and intra-class variability of fetal heart rate (FHR) data, distinguishing normal babies from acidotic fetuses is extremely challenging. This research proposes a novel multimodal dual-branch fusion network to improve the accuracy of fetal hypoxia identification. The dual-branch network is constructed through the signal slicing method. Additionally, we present a novel attention guidance module that leverages spatial attention to capture hypoxia-related information from two branches of signal. Ultimately, the network integrates maternal electronic medical records, FHR features, and FHR signals to achieve multimodal fusion of the input features. Furthermore, label smoothing can yield better calibrated networks, thus improving classification performance even further. On the public dataset, this method obtained a sensitivity of 72.58 %, a specificity of 71.08 %, a quality index of 71.59 %, and an area under the curve of 74.70 %. This method combines maternal-fetal medicine and artificial intelligence, represents a new strategy to recognize fetal acidosis.

STUDY AND ANALYSIS OF FETAL HEART RATE MONITORING SYSTEM

Analysis of FHR variability, together with uterine muscle contractions and fetal movement activity, subject to cardiotocographic monitoring, currently play a fundamental role in fetal assessment. The strength of cardiotocography lies in that normal ranges of the results of the FHR signal analysis almost always (&gt;95%) confirm fetal wellbeing. Unfortunately, questionable or abnormal signal features may indicate both fetal distress and its absence. The classic fetal heart rate variability analysis consists in determining the FHR baseline and then in identifying bradycardia/tachycardia, acceleration/deceleration patterns as well as the type and amplitude of oscillations. A more advanced FHR analysis is aimed at evaluating instantaneous FHR variability, especially with beat-to-beat approach, which is very important in fetal condition assessment. The most common technique of recording the FHR signal is the Doppler ultrasound method, which makes it difficult to correctly estimate the instantaneous heart rate variability because the measurements are averaged. On the other hand, instantaneous heart rate variability plays a crucial role in the diagnosis of fetal condition [1]. The increased interest in monitoring the fetal cardiac bioelectrical activity is due to the fact that the analysis of the fetal electrocardiogram ensures high efficiency and accuracy of the heart rate measurement even on a beat-to-beat level. The first fetal electrocardiogram was recorded as early as in the 1960-ies by means of a special spiral electrode enabling direct signal registration from a fetal head. Due to the way the electrode is placed, its use is limited only to the advanced labour stage [1]..

Gestational buprenorphine-naloxone exposure and fetal neurobehavior

BackgroundBuprenorphine-naloxone treatment may confer substantial benefits for the treatment of opioid use disorder (OUD) during pregnancy including lower risk for overdose/death, less diversion potential and reduced use of other substances. Treatment may also result in less severe Neonatal Abstinence Syndrome (NAS), but little is known about the effects of this medication on fetal neurodevelopment. MethodsThe purpose of the current study is to evaluate neurobehaviors among fetuses exposed to buprenorphine-naloxone at four time points over the second and third trimesters of gestation in pregnant women with OUD on buprenorphine-naloxone therapy. Sixty minutes of continuous fetal monitoring via fetal actocardiograph with a single wide array abdominal transducer took place at times of peak and trough buprenorphine-naloxone levels in 24 pregnant women. Data collection, which included measures of fetal heart rate and motor activity, was conducted between 24 and 36 weeks gestation, with the majority (84.6%) monitored at two or more gestational ages. Medication dose and other substance use was monitored throughout the study and infant NAS severity was assessed. ResultsFetal heart rate (FHR), FHR variability, accelerations in FHR, and motor activity were suppressed when buprenorphine-naloxone levels were at pharmacologic peak as compared to trough concentrations at 36 weeks, but not earlier in gestation. Maternal medication dose was unrelated to infant NAS severity. ConclusionsConclusions: There were evident subclinical fetal neurophysiological responses at times of peak maternal buprenorphine/naloxone levels in later gestation, similar to those previously described for buprenorphine only. Further studies evaluating the effects of these changes in fetal neurobehaviors on the longer-term infant development are needed.

Fetal magnetocardiographic recordings with a prototype bed-based array system of optically-pumped magnetometers

ObjectiveTo record and extract features of fetal cardiac activities with a semi-rigid prototype optically-pumped magnetometers (OPM) sensor array. MethodsFetal magnetocardiography (fMCG) data were collected from 15 pregnant women between 28 and 40 weeks gestation. Mothers were lying flat in a customized bed with sensors touching their abdomen from below using a prototype grid. fMCG was extracted to perform standard fetal heart rate variability (FHRV) analysis. ResultsfMCG was observed in 13 of the 15 pregnant women. OPM FHRV indicators were in the range of previous SQUID studies. ConclusionSemi-rigid prototype OPM system has the ability to record quality fMCG. fMCG is capable of identifying lethal cardiac rhythm disturbances in the fetus. Our novel application of OPM technology may lower costs and increase maternal comfort, thus expanding fMCG's generalizability.

Mapping Early Brain-Body Interactions: Associations of Fetal Heart Rate Variation with Newborn Brainstem, Hypothalamic, and Dorsal Anterior Cingulate Cortex Functional Connectivity.

The autonomic nervous system (ANS) regulates the body's physiology, including cardiovascular function. As the ANS develops during the second to third trimester, fetal heart rate variability (HRV) increases while fetal heart rate (HR) decreases. In this way, fetal HR and HRV provide an index of fetal ANS development and future neurobehavioral regulation. Fetal HR and HRV have been associated with child language ability and psychomotor development behavior in toddlerhood. However, their associations with postbirth autonomic brain systems, such as the brainstem, hypothalamus, and dorsal anterior cingulate cortex (dACC), have yet to be investigated even though brain pathways involved in autonomic regulation are well established in older individuals. We assessed whether fetal HR and HRV were associated with the brainstem, hypothalamic, and dACC functional connectivity in newborns. Data were obtained from 60 pregnant individuals (ages 14-42) at 24-27 and 34-37 weeks of gestation using a fetal actocardiograph to generate fetal HR and HRV. During natural sleep, their infants (38 males and 22 females) underwent a fMRI scan between 40 and 46 weeks of postmenstrual age. Our findings relate fetal heart indices to brainstem, hypothalamic, and dACC connectivity and reveal connections with widespread brain regions that may support behavioral and emotional regulation. We demonstrated the basic physiologic association between fetal HR indices and lower- and higher-order brain regions involved in regulatory processes. This work provides the foundation for future behavioral or physiological regulation research in fetuses and infants.

Computer Vision for Identification of Increased Fetal Heart Variability in Cardiotocogram

Introduction: Increased fetal heart rate variability (IFHRV), defined as fetal heart rate (FHR) baseline amplitude changes of >25 beats per minute with a duration of ≥1 min, is an early sign of intrapartum fetal hypoxia. This study evaluated the level of agreement of machine learning (ML) algorithms-based recognition of IFHRV patterns with expert analysis. Methods: Cardiotocographic recordings and cardiotocograms from 4,988 singleton term childbirths were evaluated independently by two expert obstetricians blinded to the outcomes. Continuous FHR monitoring with computer vision analysis was compared with visual analysis by the expert obstetricians. FHR signals were graphically processed and measured by the computer vision model labeled SALKA. Results: In visual analysis, IFHRV pattern occurred in 582 cardiotocograms (11.7%). Compared with visual analysis, SALKA recognized IFHRV patterns with an average Cohen’s kappa coefficient of 0.981 (95% CI: 0.972–0.993). The sensitivity of SALKA was 0.981, the positive predictive rate was 0.822 (95% CI: 0.774–0.903), and the false-negative rate was 0.01 (95% CI: 0.00–0.02). The agreement between visual analysis and SALKA in identification of IFHRV was almost perfect (0.993) in cases (N = 146) with neonatal acidemia (i.e., umbilical artery pH <7.10). Conclusions: Computer vision analysis by SALKA is a novel ML technique that, with high sensitivity and specificity, identifies IFHRV features in intrapartum cardiotocograms. SALKA recognizes potential early signs of fetal distress close to those of expert obstetricians, particularly in cases of neonatal acidemia.

Abnormal umbilical cord coiling and association with pregnancy factors.

The umbilical cord, as a connecting bridge between two lives, plays an important role in fetal development. Though studies on the umbilical cord date back many years, extensive studies on certain umbilical cord characteristics, such as umbilical cord coiling, are rare. Cord coiling, measured by the umbilical coiling index, is a physiological phenomenon that offers resistance to external pressures. Umbilical cord coiling is a result of several factors, both environmental and genetic. However, umbilical cords sometimes coil abnormally, resulting in hypocoiling, hypercoiling, or non-coiling which have significant associations with adverse perinatal outcomes. An all-language literature search was conducted on Medline from 1970 to 2023. The following search terms were used; umbilical cord; umbilical coiling; coiling index; abnormal coiling; perinatal outcomes, and cross-referencing yielded further information. We comprehensively reviewed the literature on umbilical cord coiling, factors contributing to coiling, abnormal coiling of the umbilical cord, and the association with several factors including maternal age, gravida, gestational diabetes mellitus, pre-eclampsia, abruption, birth weight, intrauterine growth retardation, maternal iron status, small for gestational age, fetal heart rate variations, ponderal index, and sought possible explanations.

Correlation of fetal heart rate dynamics to inflammatory markers and brain-derived neurotrophic factor during pregnancy.

This study aims to show the relation between biomarkers in maternal and cord-blood samples and fetal heart rate variability (fHRV) metrics through a non-invasive fetal magnetocardiography (fMCG) technique. Twenty-three women were enrolled for collection of maternal serum and fMCG tracings immediately prior to their scheduled cesarean delivery. The umbilical cord blood was collected for measurement of biomarker levels. The fMCG metrics were then correlated to the biomarker levels from the maternal serum and cord blood. Brain-derived neurotrophic factor (BDNF) had a moderate correlation with fetal parasympathetic activity (0.416) and fetal sympathovagal ratios (-0.309;-0.356). Interleukin (IL)-6 also had moderate-sized correlations but with an inverse relationship as compared to BDNF. These correlations were primarily in cord-blood samples and not in the maternal blood. In this small sample-sized exploratory study, we observed a moderate correlation between fHRV and cord-blood BDNF and IL-6 immediately preceding scheduled cesarean delivery at term. These findings need to be validated in a larger population.

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.

Is lower fetal heart rate variability a susceptibility marker to the impact of negative coparenting on infant regulatory capacity?

Lower fetal heart rate variability (FHRV) may be a prenatal endophenotypic susceptibility marker and increase the impact of both positive and negative coparenting on infant regulatory capacity. This study analyzed the moderator role of FHRV in the association between positive and negative coparenting and infant regulatory capacity at 3 months. The sample comprised 86 first-born infants and their mothers and fathers recruited at a public Health Service in Northern Portugal. FHRV was recorded during routine cardiotocography examination at the third trimester of gestation. Mothers and fathers reported on coparenting and infant regulatory capacity at 2 weeks and 3 months postpartum. FHRV moderated the association between mother's and father's negative coparenting at 2 weeks postpartum and infant regulatory capacity at three months. Infants with low FHRV presented higher regulatory capacity when mothers or fathers reported less negative coparenting, while lower regulatory capacity when mothers or fathers reported more negative coparenting, than infants with high FHRV. Findings suggested lower FHRV as a prenatal endophenotypic susceptibility marker that increases the impact of negative coparenting on infant regulatory capacity.

Effect of dural puncture epidural block technique on fetal heart rate variability during labor analgesia

Purpose To explore the effect of dural puncture epidural (DPE) block technique on fetal heart rate variability (HRV) during labor analgesia. Methods Sixty full-term primiparas who were in our hospital from April 2021 to October 2021 were selected and randomized into epidural analgesia (CEA) and dural puncture epidural analgesia (DPEA) groups (n = 30). After a successful epidural puncture, routine epidural catheter (EC) was performed in CEA group, and spinal anesthesia needle (as an EC) was used to puncture the dura mater to subarachnoid space in DPE group. Anesthetics were injected through EC. The time when the temperature sensation plane reached T10 (W1) and visual analog pain score (VAS), baseline heart rate score, amplitude variation score, cycle variation score, acceleration score, deceleration score, and total score of the first contraction after W1 were recorded. Apgar scores at 1 min, 5 min, and 10 min of neonates after delivery were recorded. Results The onset time of anesthesia in CEA group was significantly longer than that in DPEA group (p < .05). However, there are no significant differences in W1, VAS, baseline heart rate score, amplitude variation score, cycle variation score, acceleration score, deceleration score, and total score of the first contraction after W1 between the two groups (p > .05). Moreover, the Apgar scores at 1 min, 5 min and 10 min of neonates after delivery were not notably different between the two groups (p > .05). Conclusion Compared with CEA, DPE block technique in labor analgesia relieves maternal pain without adverse effects on fetal HRV and newborns.

Early heart rate variability changes during acute fetal inflammatory response syndrome: An experimental study in a fetal sheep model.

Fetal infection during labor with fetal inflammatory response syndrome (FIRS) is associated with neurodevelopmental disabilities, cerebral palsy, neonatal sepsis, and mortality. Current methods to diagnose FIRS are inadequate. Thus, the study aim was to explore whether fetal heart rate variability (HRV) analysis can be used to detect FIRS. In chronically instrumented near-term fetal sheep, lipopolysaccharide (LPS) was injected intravenously to model FIRS. A control group received saline solution injection. Hemodynamic, blood gas analysis, interleukin-6 (IL-6), and 14 HRV indices were recorded for 6 h. In both groups, comparisons were made between the stability phase and the 6 h following injection (H1-H6, respectively) and between LPS and control groups. Fifteen lambs were instrumented. In the LPS group (n = 8), IL-6 increased significantly after LPS injection (p < 0.001), confirming the FIRS model. Fetal heart rate increased significantly after H5 (p < 0.01). In our FIRS model without shock or cardiovascular decompensation, five HRV measures changed significantly after H2 until H4 in comparison to baseline. Moreover, significant differences between LPS and control groups were observed in HRV measures between H2 and H4. These changes appear to be mediated by an increase of global variability and a loss of signal complexity. As significant HRV changes were detected before FHR increase, these indices may be valuable for early detection of acute FIRS.

Prospects for the study of some electrophysiological parameters in the diagnosis of fetal growth restriction

Background. Fetal growth restriction is a clinical syndrome that has adverse effects on both perinatal outcomes and human health in adulthood. Traditional approaches to the diagnosis of this syndrome are based on ultrasound biometry and dopplerometry of uteroplacental and fetal-umbilical blood flow. The equipment used for such research is very expensive, and the training of a qualified specialist takes a long time. Non-invasive electrocardiography makes it possible to evaluate fetal heart rate variability and morphological parameters of the pQRST complex. The purpose: to determine indices of heart rate variability and morphological parameters based on the data of fetal non-invasive electrocardiography, which can be used to diagnose fetal growth restriction. Materials and methods. Two hundred and twenty pregnant women aged 18 to 40 years on 24–41 weeks of gestation were enrolled in the study. All of them were divided into two groups: 108 women with fetal growth restriction were included in group I, and 112 patients with healthy fetuses in group II. The fetal electrocardiogram was recorded in abdominal lead for 30–60 minutes. Results. The performed work made it possible to detect statistically significant changes in some indices of heart rate variability on the background of fetal growth restriction: SI, TP, AC/DC, LF, LF/HF ratio, as well as morphological parameters: QTc duration, QRS complex width and T/QRS ratio. The obtained data demonstrated a violation of autonomic regulation following fetal growth restriction and reflected the tension of regulatory systems, namely, the degree of dominance of the activity of central regulatory mechanisms over autonomous ones. Impaired de- and repolarization processes were a consequence of fetal myocardium remodeling due to ischemia. Conclusions. The development of algorithms for the diagnosis of fetal growth restriction using non-invasive electrocardiography requires further research of the following parameters: SI, TP, AC/DC, LF, LF/HF ratio, QTc duration, QRS complex width, and T/QRS ratio.

Exploring the Influence of Fetal Sex on Heart Rate Dynamics Using Fetal Magnetocardiographic Recordings.

Fetal sex has been associated with different development trajectories that cause structural and functional differences between the sexes throughout gestation. Fetal magnetocardiography (fMCG) recordings from 123 participants (64 females and 59 males; one recording/participant) from a database consisting of low-risk pregnant women were analyzed to explore and compare fetal development trajectories of both sexes. The gestational age of the recordings ranged from 28 to 38 weeks. Linear metrics in both the time and frequency domains were applied to study fetal heart rate variability (fHRV) measures that reveal the dynamics of short- and long-term variability. Rates of linear change with GA in these metrics were analyzed using general linear model regressions with assessments for significantly different variances and GA regression slopes between the sexes. The fetal sexes were well balanced for GA and sleep state. None of the fHRV measures analyzed exhibited significant variance heterogeneity between the sexes, and none of them exhibited a significant sex-by-GA interaction. The absence of a statistically significant sex-by-GA interaction on all parameters resulted in none of the regression slope estimates being significantly different between the sexes. With high-precision fMCG recordings, we were able to explore the variation in fHRV parameters as it relates to fetal sex. The fMCG-based fHRV parameters did not show any significant difference in rates of change with gestational age between sexes. This study provides a framework for understanding normal development of the fetal autonomic nervous system, especially in the context of fetal sex.

The value of some indices of heart rate variability in the diagnosis of fetal growth retardation

Fetal growth retardation (FGR) is one of the most serious problems in current perinatology. This pathology leads not only to the deterioration of perinatal outcomes but also significantly increases morbidity during adult life. FGR is known to be featured by its delayed “neurological maturation”. This is manifested in a decrease in autonomic nervous regulation according to the fetal heart rate variability (HRV) scores and indices. The objective: to study HRV in fetuses with normal biometric indices compared to similar parameters of growth retarded fetuses. Materials and methods. The 47 pregnant women who had fetuses with normal biometric indices (I group) and 33 patients with fetal growth retardation (II group) were included in the study. The investigation of the fetal HRV was performed by processing the R–R intervals obtained via non-invasive electrocardiogram (ECG) and involved the following indices: STV (short term variations), LTV (long term variations), AC/DC (acceleration capacity/deceleration capacity), TP (total power), SI (stress index), SDNN (standard deviation of normal to normal intervals), EnRE (entropy of the time series), D2 (correlation dimension of the time series), Z (temporary irreversibility) і FL (measure of fuzzy logic, integrated measure of HRV). Results. The obtained data indicated that the indices of fetal HRV were reduced in the patients with FGR. These indices have utility in screening programs for the detection of fetal intrauterine nutrition and growth disturbances. The results of the study allow us to believe that the ability to accelerate heart rate patterns is partly preserved even during FGR. This may indicate a very ancient phylogenetic nature of the reaction of the heart system of the fetus to its motile activity. However, decelerations according to the DC were typical for FGR. A non-invasive fetal ECG could become a useful supplementary method in the current methods’ spectrum used in perinatal medicine. Conclusions. Therefore, the development of algorithms for the diagnosis of FGR requires the inclusion of the following HRV indices: STV, LTV, DC, TP, SI, SDNN, D2, Z, and FL. These biophysical markers of FGR can be used as a screening program in conditions of lack of access to high-quality ultrasound diagnostics or be a valuable addition to existing perinatal strategies.

Fetal heart rate variability and infant self-regulation: the impact of mother’s prenatal depressive symptoms

ABSTRACT Background Foetal heart rate (FHR) variability is considered a marker of foetal neurobehavioral development associated with infant self-regulation and thus may be an early precursor of the adverse impact of mother’s prenatal depressive symptoms on infant self-regulation. Objective This study analysed the mediator role of FHR variability in the association between mother’s prenatal depressive symptoms and infant self-regulation at three months. Methods The sample comprised 86 first-born infants and their mothers. Mothers reported on depressive symptoms at the first trimester of pregnancy and on depressive symptoms and infant self-regulation at three months postpartum. FHR variability was recorded during routine cardiotocography at the third trimester of pregnancy. A mediation model was tested, adjusting for mother’s postnatal depressive symptoms. Results Higher levels of mother’s prenatal depressive symptoms were associated with both lower FHR variability and lower infant self-regulation at three months. FHR variability was associated with infant self-regulation and mediated the association between mother’s prenatal depressive symptoms and infant self-regulation at three months. Conclusion Findings suggested FHR variability as an early precursor of infant self-regulation that underlies the association between mother’s prenatal depressive symptoms and infant self-regulation. Infants of mothers with higher levels of prenatal depressive symptoms could be at risk of self-regulation problems, partially due to their lower FHR variability.

Association Between Marked Fetal Heart Rate Variability and Neonatal Acidosis: A Prospective Cohort Study

ABSTRACT Monitoring of fetal heart rate (FHR) is an important indicator of fetal well-being during labor, but it is subject to low specificity and interpretation variability; this causes the clinical effectiveness for preventing adverse outcomes to remain controversial. Fetal heart rate has inherent variability, but reduced or marked variability can reflect poor autonomic activity, indicating conditions such as fetal acidosis. Recent research has highlighted that marked variability can indicate fetal distress; more research is needed to validate and investigate this claim. This study aimed to understand the association between marked FHR variability during labor and subsequent neonatal acidosis. Data were collected from 2 French maternity units; inclusion criteria extended to women at 37 weeks' gestation or greater, with continuous FHR monitoring during labor. Exclusion criteria were intrauterine fetal death, medical termination, multiple pregnancies, noncephalic presentation, and cesarean delivery. The primary outcome for this study was neonatal acidosis, or an umbilical artery pH of less than or equal to 7.10. Secondary outcomes included severe acidosis (pH ≤7.0), a 5-minute Apgar score of less than 7, respiratory distress, neonatal intensive care unit admission, neonatal infection, and neonatal death. Final analysis included 4394 women who gave birth between January 1 and December 31, 2019. Of this population, 177 neonates experienced marked variability in FHR within 1 hour before delivery, with a median duration of marked variability of 2 minutes. Prevalence of neonatal acidosis was 15.3% in neonates who experienced marked FHR variability and 5.6% in those who did not (aRR, 2.30; 95% confidence interval [CI], 1.53–3.44). In addition, those with marked FHR variability more often experienced respiratory distress (aRR, 1.73; 95% CI, 1.15–2.58). Analysis was subsequently performed according to the National Institute of Child Health and Human Development category of FHR; the association between FHR variability and neonatal acidosis was significant in category I (aRR, 5.48; 95% CI, 1.88–15.96) and category II (aRR, 2.29; 95% CI, 1.40–3.74) groups. Category III FHR, however, had no significant association. Strengths of this study include the prospective cohort design, as well as generalizability. Subcategory assessment of the FHR patterns allowed for more accurate examination of the risk of neonatal acidosis. Limitations include an observational design and the strict exclusion criteria required to minimize bias, which reduces generalizability to low-risk groups. The findings of this study are consistent with previous literature in that FHR variability can be a significant marker for fetal outcomes. Clinically, these results can help providers recognize the risk of fetal and neonatal acidosis. Further research is needed to delineate further associations and assess interpretations of pattern variability.