Clinician Identification of Birth Asphyxia Using Intrapartum Cardiotocography Among Neonates With and Without Encephalopathy in New Zealand

Correlation of cardiotocography with combined APGAR scores and diagnostic performance of umbilical cord parameters in predicting low combined APGAR scores - A prospective Cohort study

Objectives

Combined Apgar score includes utilization of interventions such as Continuous positive airway pressure, Oxygen, Mask and Bag ventilation, I ntubation and ventilation, Ne onatal chest compression, Drugs, and newborn assessment. It has been proposed as a substitute for conventional Apgar score which is the gold standard for evaluating newborns right after birth but is impacted by medical interventions and preterm. Combined Apgar scores were examined to check for correlation with CTG tracing and umbilical cord blood parameters which gives an objective assessment of fetal hypoxia, in response to the demand for a more accurate tool for evaluating the neonate and to be used for medico-legal purposes. The study's objectives were to (1) determine the association of combined Apgar scores with suspicious and pathological CTG (2) the association of umbilical cord parameters with low combined Apgar scores and the diagnostic performance of these parameters in predicting low combined Apgar scores.

Study design

A prospective observational cohort study was conducted in a tertiary care center in East India. 2350 consecutive laboring mothers who had completed 34 weeks of gestation underwent cardiotocography according to institutional protocol and those with suspicious and pathological CTG who delivered within 1 h of abnormal CTG were recruited. Arterial blood was analyzed and the newborn was evaluated immediately after delivery with a combined Apgar scoring system.

Results

Of the 2350 women, 50.7 % and 49.3 %, respectively, exhibited suspicious and abnormal CTG tracings. CTG was reported to have low diagnostic accuracy and specificity, with a sensitivity of 66.7 % and 88.9 %, respectively, in detecting combined Apgar at 1 and 5 min. The combined Apgar score at five minutes showed a strong association with acidosis. There was a statistically significant correlation between low combined Apgar and excess lactate and base at one and five minutes. With 100 % sensitivity and 95 % specificity, high lactate levels > 4.1 mM/L were found to predict newborn encephalopathy.

Conclusion

Umbilical cord blood parameters were found to be correlated with low combined Apgar scores. Combined Apgar scores may be a more useful tool for neonatal assessment and long-term morbidity of newborns. Additional research is required to determine whether it can take the role of conventional Apgar scores in clinical practice.

Association of maternal, fetal and labor variables with a low Apgar score in the fifth minute in term pregnancy: a case-control study

PURPOSE

To search for maternal, labor-related and fetal variables associated with low Apgar in the fifth minute in term pregnancy.

METHODS

A retrospective case-control study with term births was conducted in a public teaching hospital from 2013 to 2020. Cases were term births with Apgar score less than 7 in the fifth minute, and controls, the next one or two births following a case, with Apgar of 7 or more. Non-cephalic presentations, multiples and malformations were excluded. We accessed 100 cases and 190 controls. We considered significant values of p < 0.05.

RESULTS

Were accessed 27 variables which could be risk factors, from which 12 were associated with the outcome. We found a protective effect of prelabor cesarean for the outcome, odds ratio (OR) 0.38, p = 0.013. Consequently, we conducted two sets of analyses: in the whole group and in the group of laboring women. The values of OR were in general greater in the group of laboring women, compared with the whole group. We conducted multivariate analysis within the group of women in labor. The variables which fitted best in the model were nulliparity, male sex of the fetus, less than six prenatal visits and abnormal cardiotocography; all remained significant. An association of rupture of membranes more than 360 min with the outcome, even after controlling fpr duration of labor, was found; adjusted OR 2.45, p = 0.023.

CONCLUSION

Twelve variables were associated with the outcome. Prelabor cesarean had a protective effect. The time of ruptured membranes was associated with low Apgar.

Accounting for Nulliparity in the Prediction of Hypoxic-Ischemic Encephalopathy Using Cardiotocography

Nulliparous pregnancies, those where the mother has not previously given birth, are associated with longer labors and hence expose the fetus to more contractions and other adverse intrapartum conditions such as chorioamnionitis. The objective of the present study was to test if accounting for nulliparity could improve the detection of fetuses at increased risk of developing hypoxic-ischemic encephalopathy (HIE). During labor, clinicians assess the fetal heart rate and uterine pressure signals to identify fetuses at risk of developing HIE. In this study, we performed random forest classification using fetal heart rate and uterine pressure features from 40,831 births, including 374 that developed HIE. We analyzed a two-path classification approach that analyzed separately the fetuses from nulliparous and multiparous mothers, and a one-path classification approach that included the clinical variable for nulliparity as a classification feature. We compared these two approaches to a one-path classifier that had no information about the parity of the mothers. We also compared our results to the rate of Caesarean deliveries in each group, which is used clinically to interrupt the progression towards HIE. All the classifiers detected more fetuses that developed HIE than the observed Caesarean rate, but accounting for nulliparity did not improve performance.

Immediate and longer-term impacts of fetal surveillance education on workforce knowledge and cognitive skills

Background: Following the development of the Royal Australian College of Obstetricians and Gynaecologists Intrapartum Fetal Surveillance Guideline in 2003, an education program was developed to support guideline implementation and clinical practice. It was intended that improved clinician knowledge, particularly of cardiotocography, would reduce rates of intrapartum fetal morbidity and mortality. The program contains a multiple-choice assessment, designed to assess fetal surveillance knowledge and the application of that knowledge. We used the results of this assessment over time to evaluate the impact of the education program on clinicians' fetal surveillance knowledge and interpretive skills, in the immediate and longer-term. Methods: We undertook a retrospective analysis of the assessment results for all participants in the Fetal Surveillance Education Program, between 2004 and 2018. Classical Test Theory and Rasch Item Response Theory analysis were used to evaluate the statistical reliability and quality of the assessment, and the measurement invariance or stability of the assessments over time. Clinicians' assessment scores were then reviewed by craft group and previous exposure to the program. Results: The results from 64,430, broadly similar assessments, showed that participation in the education program was associated with an immediate improvement in clinician performance in the assessment. Performance improvement was sustained for up to 18 months following participation in the program and recurrent participation was associated with progressive improvements. These trends were observed for all craft groups (consultant obstetricians, doctors in training, general practitioners, midwives, student midwives). Conclusions: These findings suggest that the Fetal Surveillance Education Program has improved clinician knowledge and the associated cognitive skills over time. The stable difficulty of the assessment tool means any improvement in clinician's results, with ongoing exposure to the program, can be reliably assessed and demonstrated. Importantly this holds true for all craft groups involved in intrapartum care and the interpretation of cardiotocography.

Timely Detection of Infants at Risk of Intrapartum Acidosis and Hypoxic-Ischemic Encephalopathy Using Cardiotocography. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2023;2023:1-5. [PMID: 38083649 DOI: 10.1109/embc40787.2023.10340095]

This work aims to improve the intrapartum detection of fetuses with an increased risk of developing fetal acidosis or hypoxic-ischemic encephalopathy (HIE) using fetal heart rate (FHR) and uterine pressure (UP) signals. Our study population comprised 40,831 term births divided into 3 classes based on umbilical cord or early neonatal blood gas assessments: 374 with verified HIE, 3,047 with acidosis but no encephalopathy and 37,410 healthy babies with normal gases. We developed an intervention recommendation system based on a random forest classifier. The classifier was trained using classical and novel features extracted electronically from 20-minute epochs of FHR and UP. Then, using the predictions of the classifier on each epoch, we designed a decision rule to determine when to recommended intervention. Compared to the Caesarean rates in each study group, our system identified an additional 5.68% of babies who developed HIE (54.55% vs 60.23%, p < 0.01) with a specific alert threshold. Importantly, about 75% of these recommendations were made more than 200 minutes before birth. In the acidosis group, the system identified an additional 17.44% (37.15% vs 54.59%, p < 0.01) and about 2/3 of these recommendations were made more than 200 minutes before birth. Compared to the Caesarean rate in the healthy group, the associated false positive rate was increased by 1.07% (38.80% vs 39.87%, p<0.01).Clinical Relevance- This method recommended intervention in more babies affected by acidosis or HIE, than the intervention rate observed in practice and most often did so 200 minutes before delivery. This was early enough to expect that interventions would have clinical benefit and reduce the rate of HIE. Given the high burden associated with HIE, this would justify the marginal increase in the normal Cesarean rate.

Multimodal Deep Learning for Predicting Adverse Birth Outcomes Based on Early Labour Data

Cardiotocography (CTG) is a widely used technique to monitor fetal heart rate (FHR) during labour and assess the health of the baby. However, visual interpretation of CTG signals is subjective and prone to error. Automated methods that mimic clinical guidelines have been developed, but they failed to improve detection of abnormal traces. This study aims to classify CTGs with and without severe compromise at birth using routinely collected CTGs from 51,449 births at term from the first 20 min of FHR recordings. Three 1D-CNN and LSTM based architectures are compared. We also transform the FHR signal into 2D images using time-frequency representation with a spectrogram and scalogram analysis, and subsequently, the 2D images are analysed using a 2D-CNNs. In the proposed multi-modal architecture, the 2D-CNN and the 1D-CNN-LSTM are connected in parallel. The models are evaluated in terms of partial area under the curve (PAUC) between 0-10% false-positive rate; and sensitivity at 95% specificity. The 1D-CNN-LSTM parallel architecture outperformed the other models, achieving a PAUC of 0.20 and sensitivity of 20% at 95% specificity. Our future work will focus on improving the classification performance by employing a larger dataset, analysing longer FHR traces, and incorporating clinical risk factors.

Association between marked fetal heart rate variability and neonatal acidosis: A prospective cohort study

OBJECTIVE

To assess the association between marked variability in fetal heart rate (FHR) and neonatal acidosis.

DESIGN

Bicentric prospective cohort study.

SETTING

From January 2019 to December 2019, in two French tertiary care maternity units.

POPULATION

Women in labour at ≥37 weeks of gestation, with continuous FHR monitoring until delivery and with the availability of umbilical arterial pH. Women with intrauterine fetal death or medical termination, multiple pregnancies, non-cephalic presentation or planned caesarean delivery were excluded.

METHODS

The exposure was marked variability in FHR in the 60 minutes before delivery, defined as a variability greater than 25 beats per minute, with a minimum duration of 1 minute. To assess the association between marked variability and neonatal acidosis, we used multivariable modified Poisson regression modelling. We then conducted subgroup analyses according to the US National Institute of Child Health and Human Development (NICHD) category of the associated fetal heart rate.

MAIN OUTCOME MEASURES

Neonatal acidosis, defined as an umbilical artery pH of ≤7.10.

RESULTS

Among the 4394 women included, 177 (4%) had marked variability in fetal heart rate in the 60 minutes before delivery. Acidosis occurred in 6.0% (265/4394) of the neonates. In the multivariable analysis, marked variability was significantly associated with neonatal acidosis (aRR 2.30, 95% CI 1.53-3.44). In subgroup analyses, the association between marked variability and neonatal acidosis remained significant in NICHD category-I and category-II groups.

CONCLUSIONS

Marked variability was associated with a twofold increased risk of neonatal acidosis.

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.

Risk factors for hypoxic-ischemic encephalopathy in cases of severe acidosis: A case-control study

INTRODUCTION

The aim of the study was to identify the obstetric risk factors for hypoxic-ischemic encephalopathy (HIE) in infants with asphyxia at birth.

MATERIAL AND METHODS

This multicenter case-control study covered the 5-year period from 2014 through 2018 and included newborns ≥36 weeks of gestation with an umbilical pH at birth ≤7.0. Cases were newborns who developed moderate or severe HIE; they were matched with controls with pH ≤7.0 at birth over the same period without moderate or severe HIE. The factors studied were maternal, gestational, intrapartum, delivery-related, and neonatal characteristics. A multivariable analysis was performed to study the maternal, obstetric, and neonatal factors independently associated with moderate or severe HIE.

RESULTS

Our review of the records identified 41 cases and 98 controls. Compared with controls, children with moderate or severe HIE had a lower 5-min Apgar score, lower umbilical artery pH, and higher cord lactate levels at birth and at 1 h of life. Obstetric factors associated with moderate or severe HIE were the occurrence of an acute event (adjusted odds ratio [aOR] 6.4; 95% confidence interval [CI] 1.8-22.5), maternal fever (aOR 3.5; 95% CI 1.0-11.9), and thick meconium during labor (aOR 2.9; 95% CI 1.0-8.6).

CONCLUSIONS

HIE is associated with a lower 5-min Apgar score and with the severity of acidosis at birth and at 1 h of life. In newborns with a pH <7.0 at birth, the occurrence of an acute obstetric event, maternal fever, and thick meconium are independent factors associated with moderate or severe HIE.

Physiological CTG categorization in types of hypoxia compared with MRI and neurodevelopmental outcome in infants with HIE

BACKGROUND

Commonly used methods of CTG classification do not reliably predict neonatal hypoxic-ischemic encephalopathy (HIE).

OBJECTIVE

To examine whether a relationship exists between the types of hypoxia as identified on the cardiotocograph using novel physiology-based CTG classification and patterns of injury on neonatal cerebral MRI and later neurodevelopmental outcomes.

STUDY DESIGN

A retrospective study of term-born infants admitted to four neonatal units with HIE as part of a brain injury biomarkers study between January 2014 and December 2015. Intrapartum CTG traces were analyzed by two obstetricians trained in physiological CTG classification, blind to neonatal outcomes. Neonatal cerebral MR images were assessed independently by a neuroradiologist and an expert neonatologist. CTG traces were classified into types of hypoxia and allocated to groups; (1) chronic hypoxia or antepartum injury; (2) gradually evolving or subacute hypoxia; and (3) acute hypoxia.

RESULTS

Of 106 infants recruited to the study, records were available for 58 cases. Of these, CTGs were available for 37. All 37 had abnormal CTGs. Twenty-four infants, all of whom had received therapeutic hypothermia had cerebral MRI. Fourteen of the 24 (58%) infants had abnormal MRI. In group 1 (chronic hypoxia/antenatal injury), total brain injury was most predominant (4/6 infants). Group 2 (gradually evolving/subacute hypoxia) was associated with peripheral brain injury (5/5 infants). Group 3 (acute hypoxia) was associated with basal-ganglia thalamic injury pattern (3/3 infants). Later neurodevelopmental outcomes were available for 35 cases. Infants suspected to have a pre-labor injury on CTG (group 1) had a higher proportion of adverse neurodevelopmental outcomes (4/10, 40%) compared to groups 2 and 3 (4/25, 16%).

CONCLUSION

Using this novel physiology-based CTG classification, we demonstrate an association between types of hypoxia observed on the CTG and MRI patterns of hypoxic brain injury. Infants with CTG trace suggestive of chronic hypoxia or other antenatal injuries were overrepresented in this cohort and were also more likely to have a poor neurodevelopmental outcome.

The impact on obstetric and perinatal outcomes in term infants following the introduction of a colour-coded, hierarchical cardiotocography classification system: A retrospective non-inferiority study

BACKGROUND

Queensland introduced a colour-coded cardiotocograph (CTG) classification system (green, blue, yellow and red) to complement the Royal Australian and New Zealand College of Obstetricians and Gynaecologists prose-based classification system of 'low, unlikely, maybe or likely' fetal compromise.

AIMS

The aim of the study was to determine the clinical impact of the introduction of the colour-coded CTG classification system compared to the prose-based system. We hypothesised there would be no change in the rate of operative delivery for intrapartum fetal compromise (OD-IFC).

MATERIALS AND METHODS

This retrospective non-inferiority study from November 2014 to May 2018 used routinely collected data from the Mater Mother's Hospital. Non-insured women with a singleton, non-anomalous, cephalic fetus at term, attempting a vaginal birth with continuous intrapartum CTG were included. The primary outcome was OD-IFC. Secondary outcomes included various obstetric and perinatal outcomes. Non-inferiority analysis was performed with a pre-specified non-inferiority margin of 2% risk difference.

RESULTS

Eleven thousand seven hundred and twenty-seven participants were included. The OD-IFC rate was similar across the study groups (prose-based 15.1% vs colour-coded 15.3%, adjusted odds ratio (aOR) 1.02, 95% CI 0.93-1.13) with the adjusted risk difference of 0.29% (95% CI -0.98 to 1.56), which did not exceed the inferiority margin. There were more spontaneous (aOR 1.11, 95% CI 1.04-1.19) and fewer instrumental (aOR 0.87, 95% CI 0.80-0.95) vaginal births in the colour-coded cohort. There were no differences in neonatal outcomes.

CONCLUSIONS

Reassuringly, the colour-coded CTG classification system was non-inferior to the prose-based system, did not influence OD-IFC but was associated with more spontaneous vaginal deliveries.

Effect of intra-partum Oxytocin on neonatal encephalopathy: a systematic review and meta-analysis

Background

Oxytocin is widely used for induction and augmentation of labour, particularly in low- and middle-income countries (LMICs). In this systematic review and meta-analysis, we examined the effect of intra-partum Oxytocin use on neonatal encephalopathy.

Methods

The protocol for this study was registered with PROSPERO (ID: CRD42020165049). We searched Medline, Embase and Web of Science Core Collection databases for papers published between January 1970 and May 2021. We considered all studies involving term and near-term (≥36 weeks’ gestation) primigravidae and multiparous women. We included all randomised, quasi-randomised clinical trials, retrospective studies and non-randomised prospective studies reporting intra-partum Oxytocin administration for induction and/or augmentation of labour. Our primary outcome was neonatal encephalopathy. Risk of bias was assessed in non-randomised studies using the Risk Of Bias In Non-randomised Studies of Interventions (ROBINS-I) tool. The RoB 2.0 tool was used for randomised studies. A Mantel-Haenszel statistical method and random effects analysis model were used for meta-analysis. Odds ratios were used to determine effect measure and reported with 95% confidence intervals.

Results

We included data from seven studies (6 Case-control studies, 1 cluster-randomised trial) of which 3 took place in high-income countries (HICs) and 4 in LMICs. The pooled data included a total of 24,208 women giving birth at or after 36 weeks; 7642 had intra-partum Oxytocin for induction and/or augmentation of labour, and 16,566 did not receive intra-partum Oxytocin. Oxytocin use was associated with an increased prevalence of neonatal encephalopathy (Odds Ratio 2.19, 95% CI 1.58 to 3.04; p < 0.00001).

Conclusions

Intra-partum Oxytocin may increase the risk of neonatal encephalopathy. Future clinical trials of uterotonics should include neonatal encephalopathy as a key outcome.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-04216-3.

Estimation and Discriminability of Doppler Ultrasound Fetal Heart Rate Variability Measures

Continuous electronic fetal monitoring and the access to databases of fetal heart rate (FHR) data have sparked the application of machine learning classifiers to identify fetal pathologies. However, most fetal heart rate data are acquired using Doppler ultrasound (DUS). DUS signals use autocorrelation (AC) to estimate the average heartbeat period within a window. In consequence, DUS FHR signals loses high frequency information to an extent that depends on the length of the AC window. We examined the effect of this on the estimation bias and discriminability of frequency domain features: low frequency power (LF: 0.03–0.15 Hz), movement frequency power (MF: 0.15–0.5 Hz), high frequency power (HF: 0.5–1 Hz), the LF/(MF + HF) ratio, and the nonlinear approximate entropy (ApEn) as a function of AC window length and signal to noise ratio. We found that the average discriminability loss across all evaluated AC window lengths and SNRs was 10.99% for LF 14.23% for MF, 13.33% for the HF, 10.39% for the LF/(MF + HF) ratio, and 24.17% for ApEn. This indicates that the frequency domain features are more robust to the AC method and additive noise than the ApEn. This is likely because additive noise increases the irregularity of the signals, which results in an overestimation of ApEn. In conclusion, our study found that the LF features are the most robust to the effects of the AC method and noise. Future studies should investigate the effect of other variables such as signal drop, gestational age, and the length of the analysis window on the estimation of fHRV features and their discriminability.

Perinatal asphyxia from the obstetric standpoint

Perinatal asphyxia remains one of the major causes of morbidity and mortality for term newborns. Though access to health care and birth attendants have decreased the rate, Neonatal encephalopathy (NE) has not been eliminated. Worldwide, women at socioeconomic disadvantage have the highest risk of delivering a neonate with NE. Neonates that will experience perinatal asphyxia cannot be easily identified prospectively and the intrapartum testing available is not specific enough to clearly indicate the best course of action in most cases. Despite this, training programs that aim to decrease morbidity and mortality from all causes appear to be associated with fewer cases of perinatal asphyxia. The current best approach is to support education and communication for all people involved in the care of birthing women. Ideally, new technology will address identification of the fetus likely to be affected or the fetus who is beginning to experience injury in advance of delivery.