Fetal Heart Rate Decelerations Research Articles

A deep learning method for locating fetal heart rate decelerations during labour using crowd-sourced data

Monitoring the heart rate of a fetus is the only method for continuously monitoring fetal well-being during labour. Decelerations in the fetal heart rate, usually corresponding with contractions, provide information regarding the ability of the fetus to cope with a reduced oxygen supply caused by contractions. For this reason, visual and computer-based assessments of fetal well-being depend upon the correct identification of decelerations. Agreement between clinical professionals when identifying these features is poor. Automated methods offer a more consistent alternative, but must perform at a level comparable to a trained human observer. Collecting data to train these systems can be difficult due to time restraints on experts in fetal medicine. In this study, we designed a website to crowd-source data from clinical professionals at their convenience. This data was combined with that from other publicly available sources to produce a dataset that was used to train a convolutional auto-encoder to locate decelerations. Crowd-sourcing was found to be an effective method for collecting data that was suitable to successfully train a deep learning model to locate decelerations. The model trained using this data provided a comparable level of accuracy to users of the website and other models used for the same purpose.

Recognition of Chorioamnionitis on the Cardiotocograph (CTG): The role of the “Chorio Duck Score”

Chorioamnionitis refers to the inflammation of the chorion and amnion by the bacteria and their toxins as well as by the inflammatory cytokines. Therefore, it is a fetal disease with the bacteria, their toxins as well as the fetal immunological responses involving inflammatory cytokines (interleukins, interferons, and tumour necrosis factor-alpha) exerting their detrimental effects within the fetal compartment (i.e., amniotic fluid, fetal membranes, the placenta, and fetal tissues and organs). The vast majority of fetal inflammation occurs as a result of an ascending infection (i.e., entry of the bacteria from the maternal genital tract through the cervix). Therefore, maternal signs (tachycardia and pyrexia) may not be observed until the late stages of the disease. Cardiotocograph (CTG) trace was introduced into clinical practice in the 1960s as a tool to timely recognise ongoing fetal hypoxic stress so that immediate action could be taken to avoid hypoxic ischaemic encephalopathy (HIE) and/ or intrapartum hypoxia-related perinatal deaths. Unfortunately, the CTG was introduced into clinical practice without any prior randomised controlled trials, which resulted in panicking and reacting to the observed morphology of fetal heart rate decelerations, which reflect an ongoing fetal compensatory response to reduce the myocardial workload. A sudden and reflex reduction of the heart rate in response to ongoing intermittent hypoxic stress (i.e., repetitive compression of the umbilical cord or interruptions in uteroplacental oxygenation due to uterine contractions) would ensure a reduction in myocardial oxygen demand and maintenance of aerobic metabolism to avoid the onset of anaerobic metabolism and production of lactic acid within the myocardium. Lack of understanding of fetal compensatory responses resulted in the illogical approach of grouping arbitrary features into different categories and then randomly combining them to classify the CTG traces into “Normal, Suspicious, and Pathological”. The same parameters were used in fetuses with chorioamnionitis with an alternative, inflammatory pathway of neurological injury. The international consensus guidelines of physiological interpretation of CTG produced by 44 CTG experts from 14 countries in 2018 ensured a paradigm shift and recommended classification of CTG traces based on the type of fetal hypoxia and fetal response to stress, by applying the knowledge of fetal physiology whilst interpreting CTG traces. During the last 5 years, research has highlighted CTG features in fetal neuro-inflammation, which include an absence of fetal heart rate cycling, the ZigZag Pattern, and sinusoidal patterns. The proposed “Chorio Duck Score” is a scoring system based on recently published scientific evidence on CTG features in subclinical and clinical chorioamnionitis to enable timely diagnosis of fetal systemic inflammatory response syndrome (FIRS). This will help avoid the continuation of super-imposed hypoxic stress (i.e., progressive increasing frequency, duration, and strength of uterine contractions) on the background fetal inflammation, to prevent fetal neurological injury.

Efficacy and safety of oral and vaginal administration of misoprostol for induction of labor in high-risk obese pregnant women with hypertension or diabetes mellitus

Objective This study aims to compare the safety and efficacy of misoprostol administered orally and vaginally in obese pregnant women at term with either gestational hypertension or diabetes. Methods A total of 264 pregnant women were enrolled and categorized into two groups based on their primary condition: hypertension (134 cases) or diabetes mellitus (130 cases) and were further divided into subgroups for misoprostol administration: orally (Oral group) or vaginally (Vaginal group). The primary outcomes measured were changes in the Bishop score following treatment, induction of labor (IOL) success rates, requirement for oxytocin augmentation, duration of labor, mode of delivery, and cesarean section rates. Results Significant enhancements in Bishop scores, decreased cesarean section rates and increased success rates of IOL were noted in both administration groups. The incidence of vaginal delivery within 24 h was significantly higher in the Vaginal group compared to the Oral group. Adverse effects, including nausea, uterine overcontraction, hyperfrequency of uterine contraction and uterine hyperstimulation without fetal heart rate deceleration, were significantly more prevalent in the Vaginal group than in the Oral group. Conclusion Misoprostol administration, both orally and vaginally, proves effective for labor induction in obese pregnant women with hypertension or diabetes. However, the oral route presents a lower risk of adverse maternal and neonatal outcomes, suggesting its preference for safer labor induction in this demographic.

Uterine dynamics, blood profiles, and electronic fetal monitoring of primiparous and multiparous bitches classified according to their weight.

Perinatal mortality occurs in all species. In dogs, mortality rates have been reported to range from 5 to 35%. Electronic fetal and uterine monitoring has recently been used in domestic animals to monitor the mother and newborn before and during parturition. In this way, the fetal heart rate and uterine dynamics can be monitored. This study evaluated the uterine dynamics of bitches with different weights and parity. Ninety-six bitches and their 476 puppies were divided into four experimental groups containing 24 individuals each (12 primiparous bitches and 12 multiparous bitches), according to body weight: G1 (4-8 kg), G2 (8.1-16 kg), G3 (16.1 to 32 kg), and G4 (32.1 to 39.6 kg). The fetal heart rate decelerations (dip 2 patterns), uterine dynamics, and bitches' blood profiles were evaluated, including levels of glucose, lactate, pCO2, pO2, pH, HCO3-, and Ca++. The dam weight can affect the vitality of newborns and the uterine dynamics, with differences in the frequency, intensity, and duration of myometrial contractions. The expulsion interval between puppies was longest in primiparous bitches with low weight and shortest in multiparous bitches with high weight. The expulsion interval and the number of stillborn females were higher in primiparous bitches with high weight. Newborn male puppies were significantly heavier than newborn females.

Adverse Fetal Outcomes in Patients with Low Amniotic Fluid Index: Presenting Care Hospital Setting

Background: Pregnancy is a critical period where various physiological parameters are monitored to ensure the well-being of both mother and fetus. Amniotic fluid index (AFI) is one such measure, with deviations from the norm, particularly low AFI, being associated with adverse fetal outcomes. This study delves into the correlation between low AFI and fetal well-being in a tertiary care setting. Objective: The aim of this study was to investigate the association between low AFI and adverse fetal outcomes and to quantify the impact of low AFI on fetal health during delivery in a tertiary care hospital. Methods: A prospective study was conducted on 100 pregnant women attending the Obstetrics and Gynecology Department of Khyber Teaching Hospital, Peshawar, from June 28 to September 27, 2023. AFI was measured using ultrasonography, with a particular focus on participants with an AFI of less than 5 cm. The study also included a systematic sample of patients across various gestational ages and recorded outcomes such as intrauterine growth restriction (IUGR), oligohydramnios-associated deformations, cord compression, variable decelerations in fetal heart rate, and the presence of meconium-stained amniotic fluid. Statistical analysis was performed using chi-square and t-tests, with a significance level set at p<0.05. Results: The mean AFI was 8.7 cm (SD = 1.5). Low AFI (<5 cm) was observed in 15% of the participants. Adverse outcomes included 6 cases of IUGR (6%), 4 cases of oligohydramnios-associated deformations (4%), 3 cases of cord compression (3%), 5 cases of variable decelerations in fetal heart rate (5%), and 8 cases of meconium-stained amniotic fluid (8%). A significant association was found between low AFI and adverse fetal outcomes (χ² = 8.43, p < 0.01). Conclusion: The study confirmed a significant correlation between low AFI and the presence of adverse fetal outcomes, emphasizing the importance of vigilant fetal monitoring and management in pregnancies with low AFI.

Prevention of fetal brain injury in category II tracings.

With category II fetal heart rate tracings, the preferred timing of interventions to prevent fetal hypoxic brain damage while limiting operative interventions remains unclear. We aimed to estimate fetal extracellular base deficit (BDecf ) during labor with category II tracings to quantify the timing of potential interventions to prevent severe fetal metabolic acidemia. A longitudinal study was conducted using the database of the Recurrence Prevention Committee, Japan Obstetric Compensation System for Cerebral Palsy, including infants with severe cerebral palsy born at ≥34 weeks' gestation between 2009 and 2014. Cases included those presumed to have an intrapartum onset of hypoxic-ischemic insult based on the fetal heart rate pattern evolution from reassuring to an abnormal pattern during delivery, in association with category II tracings marked by recurrent decelerations and an umbilical arterial BDecf ≥ 12 mEq/L. BDecf changes during labor were estimated based on stages of labor and the frequency/severity of fetal heart rate decelerations using the algorithm of Ross and Gala. The times from the onset of recurrent decelerations to BDecf 8 and 12 mEq/L (Decels-to-BD8, Decels-to-BD12) and to delivery were determined. Cases were divided into two groups (rapid and slow progression) based upon the rate of progression of acidosis from onset of decelerations to BDecf 12 mEq/L, determined by a finite-mixture model. The median Decels-to-BD8 (28 vs. 144 min, p < 0.01) and Decels-to-BD12 (46 vs. 177 min, p < 0.01) times were significantly shorter in the rapid vs slow progression. In rapid progression cases, physicians' decisions to deliver the fetus occurred at ~BDecf 8 mEq/L, whereas the "decisions" did not occur until BDecf reached 12 mEq/L in slow progression cases. Fetal BDecf reached 12 mEq/L within 1 h of recurrent fetal heart rate decelerations in the rapid progression group and within 3 h in the slow progression group. These findings suggest that cases with category II tracings marked by recurrent decelerations (i.e., slow progression) may benefit from operative intervention if persisting for longer than 2 h. In contrast, cases with sudden bradycardia (i.e., rapid progression) represent a challenge to prevent severe acidosis and hypoxic brain injury due to the limited time opportunity for emergent delivery.

Fetal Heart Rate Tracings Associated With Eclamptic Seizures

(Am J Obstet Gynecol. 2022;227:622.e1–622.e6) Complications of eclamptic seizures include postpartum hemorrhage, placental abruption, stroke, pulmonary edema from heart failure, aspiration pneumonia, preterm delivery, stillbirth, and neonatal death. Though first published in 1974, the relationship between fetal heart rate decelerations and eclampsia has not characterized the timing, duration, and frequency of these changes. This study aimed to describe and characterize fetal heart rate changes following eclampsia and determine obstetric management following seizures.

The roles of peripheral chemoreflex and myocardial hypoxia in fetal heart rate decelerations: insights from a near-term fetal sheep study.

The roles of peripheral chemoreflex and myocardial hypoxia in fetal heart rate decelerations: insights from a near-term fetal sheep study.

Prediction of Fetal Blood Pressure during Labour with Deep Learning Techniques.

Our objective is to develop a model for the prediction of minimum fetal blood pressure (FBP) during fetal heart rate (FHR) decelerations. Experimental data from umbilical occlusions in near-term fetal sheep (2698 occlusions from 57 near-term lambs) were used to train a convolutional neural network. This model was then used to estimate FBP for decelerations extracted from the final 90 min of 53,445 human FHR signals collected using cardiotocography. Minimum sheep FBP was predicted with a mean absolute error of 6.7 mmHg (25th, 50th, 75th percentiles of 2.3, 5.2, 9.7 mmHg), mean absolute percentage errors of 17.3% (5.5%, 12.5%, 23.9%) and a coefficient of determination R2=0.36. While the model was unable to clearly predict severe compromise at birth in humans, there is positive evidence that such a model could predict human FBP with further development. The neural network is capable of predicting FBP for many of the sheep decelerations accurately but performed far from satisfactory at identifying FHR segments that correspond to the highest or lowest minimum FBP. These results indicate that with further work and a larger, more variable training dataset, the model could achieve higher accuracy.

Single Sporadic Deceleration during Reactive Nonstress Test-Clinical Significance and Risk for Cesarean Delivery.

Evidence regarding the clinical significance of a single sporadic variable deceleration (SSD) in reactive non-stress test (NST) is scarce, and optimal management has yet to be established. We aim to evaluate whether SSD during a reactive NST at term is associated with a higher risk for fetal heart rate decelerations during labor and the need for intervention. This was a retrospective, case-control study of singleton term pregnancies at one university-affiliated medical center in 2018. The study group consisted of all pregnancies with an SSD in an otherwise reactive NST. For each case, two consecutive pregnancies without SSD were matched in a 1:2 ratio. The primary outcome was the rate of cesarean delivery (CD) due to non-reassuring fetal heart rate monitoring (NRFHRM). 84 women with an SSD were compared to 168 controls. SSD during antenatal fetal surveillance did not increase the rate of CD overall or for NRFHRM (17.9% vs. 13.7% and 10.7% vs. 7.7%, respectively, p > 0.05). Rates of assisted deliveries and maternal and neonatal complications were similar between the groups. SSD during a reactive NST in term pregnancies is not associated with an increased risk for adverse perinatal outcomes. SSD should not necessarily require induction of labor, and expectant management is a reasonable alternative.

Dissecting the contributions of the peripheral chemoreflex and myocardial hypoxia to fetal heart rate decelerations in near-term fetal sheep.

Brief repeated fetal hypoxaemia during labour can trigger intrapartum decelerations of the fetal heart rate (FHR) via the peripheral chemoreflex or the direct effects of myocardial hypoxia, but the relative contribution of these two mechanisms and how this balance changes with evolving fetal compromise remain unknown. In the present study, chronically instrumented near-term fetal sheep received surgical vagotomy (n=8) or sham vagotomy (control, n=11) to disable the peripheral chemoreflex and unmask myocardial hypoxia. One-minute complete umbilical cord occlusions (UCOs) were performed every 2.5min for 4h or until arterial pressure fell below 20mmHg. Hypotension and severe acidaemia developed progressively after 65.7±7.2 UCOs in control fetuses and 49.5±7.8 UCOs after vagotomy. Vagotomy was associated with faster development of metabolic acidaemia and faster impairment of arterial pressure during UCOs without impairing centralization of blood flow or neurophysiological adaptation to UCOs. During the first half of the UCO series, before severe hypotension developed, vagotomy was associated with a marked increase in FHR during UCOs. After the onset of evolving severe hypotension, FHR fell faster in control fetuses during the first 20s of UCOs, but FHR during the final 40s of UCOs became progressively more similar between groups, with no difference in the nadir of decelerations. In conclusion, FHR decelerations were initiated and sustained by the peripheral chemoreflex at a time when fetuses were able to maintain arterial pressure. After the onset of evolving hypotension and acidaemia, the peripheral chemoreflex continued to initiate decelerations, but myocardial hypoxia became progressively more important in sustaining and deepening decelerations. KEY POINTS: Brief repeated hypoxaemia during labour can trigger fetal heart rate decelerations by either the peripheral chemoreflex or myocardial hypoxia, but how this balance changes with fetal compromise is unknown. Reflex control of fetal heart rate was disabled by vagotomy to unmask the effects of myocardial hypoxia in chronically instrumented fetal sheep. Fetuses were then subjected to repeated brief hypoxaemia consistent with the rates of uterine contractions during labour. We show that the peripheral chemoreflex controls brief decelerations in their entirety at a time when fetuses were able to maintain normal or increased arterial pressure. The peripheral chemoreflex still initiated decelerations even after the onset of evolving hypotension and acidaemia, but myocardial hypoxia made an increasing contribution to sustain and deepen decelerations.

Sporadic fetal heart rate decelerations in preterm pregnancies and adverse obstetrical outcomes

Sporadic fetal heart rate decelerations (SFHRD), observed in a Non-Stress Test (NST), in low-risk pregnancies at term, is associated with an increased risk of adverse pregnancy outcomes. However, the significance of SFHRD, observed in preterm pregnancies, is still unknown. Our objective was to evaluate whether SFHRD observed in a NST performed at 28-37 weeks of gestation is associated with adverse obstetrical outcomes.

Do significant adverse reactions to labor epidural anesthesia affect interval to delivery?

Epidural anesthesia during labor may lead to maternal hypotension and changes in fetal heart rate (FHR). We have evaluated whether occurrence of such adverse reactions affect the interval to delivery after anesthesia. Cohort study of all laboring women who underwent epidural anesthesia during labor for the period October 1, 2020-December 31, 2020. Excluded were cases of elective CD, non-cephalic presentation, twins or multiples, fetal death, and gestational age < 37.0 weeks. Significant adverse reactions included severe maternal hypotension (defined as systolic blood pressure < 100 mm Hg in the 60 minutes after epidural or decreasing by >20% compared with before epidural) or presence of severe (prolonged or recurrent late) decelerations in the 60 minutes after epidural. Occurrence of any significant adverse reaction was related to the interval-to-delivery after completion of epidural anesthesia using linear regression analysis (SPSS 28). Among the 438 women in the cohort, significant adverse reactions to epidural occurred in 172 (39.2%), including severe maternal hypotension in 149 (34%) and severe FHR decelerations in 50 (11.4%). Interval-to-delivery after labor epidural anesthesia was associated with maternal age (P=0.007), body mass index (P< 0.001), cervical dilation at epidural (P< 0.001) as well as occurrence of severe adverse reactions to epidural (P=0.019), cesarean delivery (CD) (P< 0.001) and CD for non-reassuring FHR (P=0.009). Linear regression demonstrated that only cervical dilation at epidural (P< 0.001) and CD (P< 0.001) were related to interval-to-delivery after epidural, whereas adverse reactions to epidural were not (P=0.22). Although significant adverse reactions to labor anesthesia were not uncommon in our cohort, they did not independently affect interval-to-delivery after completion of anesthesia.

Diagnóstico pré-natal de bloqueio atrioventricular total secundário à lúpus materno: relato de caso

This report describes the case of a newborn with congenital complete atrioventricular (AV) block diagnosed antenatally belonging to a mother diagnosed with lupus erythematosus during pregnancy based on an echocardiogram ordered to investigate a finding of slow fetal heart rate. Pregnancy was terminated at 36 weeks with a cesarean section indicated due to preeclampsia. Neonatal resuscitation protocols and vasoactive drugs did not increase the newborn’s heart rate to above 100 beats per minute. The newborn had a pacemaker implanted 20 days after birth and recovered well. He was discharged without other measures to maintain heart rate. The disease was attributed to previously undiagnosed maternal systemic lupus erythematosus (SLE), which was investigated once the fetus was diagnosed with complete AV block. The success of the procedure derived from an accessible prenatal care program and an efficient public healthcare system.

The utilization of transperineal ultrasound following fetal heart deceleration after epidural analgesia: a case report

BackgroundWe report a case of fetal heart rate decelerations and relaxation of pelvic muscles and fetal descent using transperineal ultrasound after initiation of epidural labor analgesia.Case presentationA 32-year-old woman, G1P0 with gestational age of 40 weeks, required epidural analgesia when her cervical dilatation was 2 cm. Baseline transperineal ultrasound examination was performed before epidural puncture. The fetal heart rate tracing was normal before the initiation of analgesia. Approximately 10 min after the epidural administration of the loading dose, the patient reported onset of analgesia and the FHR tracing showed variable-decelerations. There was no hypotension or evidence of uterine tachysystole. Transperineal ultrasound was performed again after epidural analgesia took effect. The anteroposterior diameter of the levator hiatus increased from 5.3 to 6.6 cm and angle of progress increased from 116°to 133°. The relaxation of pelvic muscle and rapid descent of fetal head may have contributed to the FHR deceleration. The midwife elevated the fetal head through the vagina with her hand, and the FHR recovered soon thereafter.ConclusionsChanges in fetal heart rate after initiation of neuraxial analgesia are unpredictable. In addition to FHR and tocodynametric monitoring, performing TPU may helpful in distinguishing the reasons for FHR change and initiating corresponding corrective measures.

Signal Quality Index for the fetal heart rates: Development and improvements for fetal monitoring

Fetal heart rate (FHR) monitoring is the most widely used tool in clinics to assess fetal health. However, FHR with low-quality signals may somehow exaggerate the risk of the fetus suffering from acidemia, thus contributing to an increase in cesarean section rates. If there is an algorithm capable to identify and reject low-quality signals and then calculate heart rate parameters only on high-quality signals, inappropriate obstetric interventions may be greatly reduced. Currently, only the Signal Quality Index (SQI) is available for adults. When we applied SQI to fetal data, its performance drops dramatically. To fill the gap in the fetal signal quality index, we developed an easy-to-use Fetal heart rate Signal Quality Index (FSQI) in this paper. Firstly, we used a human-in-the-loop strategy to reduce the amount of data annotation effort. Secondly, we developed the FSQI algorithm oriented towards the fetus to identify low-quality signal segments. Further, we proposed a post-processing technique based on fine-grained recognition to identify low-quality signal segments more accurately. Finally, we applied the FSQI algorithm in combination with the existing FHR deceleration event detection algorithm to test the effectiveness of the algorithm. The results showed that the FSQI algorithm we developed achieved an overall accuracy of 99.8842% in signal quality classification, while also eliminating 94.92% of the incorrectly detected deceleration events of current state-of-the-art methods.

Fetal heart rate responses to maternal sleep-disordered breathing

Maternal sleep-disordered breathing is associated with adverse pregnancy outcomes and is considered to be deleterious to the developing fetus. Maternal obesity potentiates sleep-disordered breathing, which, in turn, may contribute to the effect of maternal obesity on adverse fetal outcomes. However, only a few empirical studies have evaluated the contemporaneous effects of maternal sleep-disordered breathing events on fetal well-being. These events include apnea and hypopnea with accompanying desaturations in oxyhemoglobin. This study aimed to reconcile contradictory findings on the associations between maternal apnea or hypopnea events and clinical indicators of fetal compromise. It also sought to broaden the knowledge base by examining the fetal heart rate and heart rate variability before, during, and after episodes of maternal apnea or hypopnea. To accomplish this, we employed overnight polysomnography, the gold standard for ascertaining maternal sleep-disordered breathing, and synchronized it with continuous fetal electrocardiography. A total of 84 pregnant women with obesity (body mass index >30 kg/m2) participated in laboratory-based polysomnography with digitized fetal electrocardiography recordings during or near 36 weeks of gestation. Sleep was recorded, on average, for 7 hours. Decelerations in fetal heart rate were identified. Fetal heart rate and heart rate variability were quantified before, during, and after each apnea or hypopnea event. Event-level intensity (desaturation magnitude, duration, and nadir O2 saturation level) and person-level characteristics based on the full overnight recording (apnea-hypopnea index, mean O2 saturation, and O2 saturation variability) were analyzed as potential moderators using linear mixed effects models. A total of 2936 sleep-disordered breathing events were identified, distributed among all but 2 participants. On average, participants exhibited 8.7 episodes of apnea or hypopnea per hour (mean desaturation duration, 19.1 seconds; mean O2 saturation nadir, 86.6% per episode); nearly half (n=39) of the participants met the criteria for obstructive sleep apnea. Only 45 of 2936 apnea or hypopnea events were followed by decelerations (1.5%). Conversely, most (n=333, 88%) of the 378 observed decelerations, including the prolonged ones, did not follow an apnea or a hypopnea event. Maternal sleep-disordered breathing burden, body mass index, and fetal sex were unrelated to the number of decelerations. Fetal heart rate variability increased during events of maternal apnea or hypopnea but returned to initial levels soon thereafter. There was a dose-response association between the size of the increase in fetal heart rate variability and the maternal apnea-hypopnea index, event duration, and desaturation depth. Longer desaturations were associated with a decreased likelihood of the variability returning to baseline levels after the event. The mean fetal heart rate did not change during episodes of maternal apnea or hypopnea. Episodes of maternal sleep apnea and hypopnea did not evoke decelerations in the fetal heart rate despite the predisposing risk factors that accompany maternal obesity. The significance of the modest transitory increase in fetal heart rate variability in response to apnea and hypopnea episodes is not clear but may reflect compensatory, delimited autonomic responses to momentarily adverse conditions. This study found no evidence that episodes of maternal sleep-disordered breathing pose an immediate threat, as reflected in fetal heart rate responses, to the near-term fetus.

Is It Time to Redefine Fetal Decelerations in Cardiotocography?

Historically, fetal heart rate (FHR) decelerations were classified into “early”, “late”, and “variable” based on their relationship with uterine contractions. So far, three different putative etiologies were taken for granted. Recently, this belief, passed down through generations of birth attendants, has been questioned by physiologists. This narrative review aimed to assess the evidence on pathophysiology behind intrapartum FHR decelerations. This narrative review is based on information sourced from online peer-reviewed articles databases and recommendations from the major scientific societies in the field of obstetrics. Searches were performed in MEDLINE/PubMed, EMBASE, and Scopus and selection criteria included studies in animals and humans, where the physiology behind FHR decelerations was explored. The greater affinity for oxygen of fetal hemoglobin than the maternal, the unicity of fetal circulation, and the high anaerobic reserve of the myocardium, ensure adequate oxygenation to the fetus, under basal conditions. During acute hypoxic stress the efficiency of these mechanisms are increased because of the peripheral chemoreflex. This reflex, activated at each uterine contraction, is characterized by the simultaneous activation of two neural arms: the parasympathetic arm, which reduces the myocardial consumption of oxygen by decreasing the FHR and the sympathetic component, which promotes an intense peripheric vasoconstriction, thus centralizing the fetal blood volume. This review summarizes the evidence supporting the hypoxic origin of FHR decelerations, therefore archiving the historical belief that FHR decelerations have different etiologies, according to their shape and relationship with uterine contractions. The present review suggests that it is time to welcome the new scientific evidence and to update the CTG classification systems.

Outstanding research paper awards of the Journal of the Chinese Medical Association in 2021.

Outstanding research paper awards of the Journal of the Chinese Medical Association in 2021.

Multi-Chain Semi-Markov Analysis of Intrapartum Cardiotocography.

Visual assessment of the evolution of fetal heart rate (FHR) and uterine pressure (UP) patterns is the standard of care in the intrapartum period. Unfortunately, this assessment has high levels of intra- and inter-observer variability. This study processed and analyzed FHR and UP patterns using computerized pattern recognition tools. The goal was to evaluate differences in FHR and UP patterns between fetuses with normal outcomes and those who developed hypoxic-ischemic encephalopathy (HIE). For this purpose, we modeled the sequence of FHR patterns and uterine contractions using Multi-Chain Semi-Markov models (MCSMMs). These models estimate the probability of transitioning between FHR or UP patterns and the dwell time of each pattern. Our results showed that in comparison to the control group, the HIE group had: (1) more frequent uterine contractions during the last 12 hours before birth; (2) more frequent FHR decelerations during the last 12 hours before birth; (3) longer decelerations during the last eight hours before birth; and (4) shorter baseline durations during the last five hours before birth. These results demonstrate that the fetuses in the HIE group were subject to a more stressful environment than those in the normal group. Clinical Relevance- Our results revealed statistically significant differences in FHR/UP patterns between the normal and HIE groups in the hours before birth. This indicates that features derived using MCSMMs may be useful in a machine learning framework to detect infants at increased risk of developing HIE allowing preventive interventions.