A prospective cohort study of fetal heart rate monitoring: deceleration area is predictive of fetal acidemia

Development, Validation, and Diagnostic Accuracy of the Fetal Lack of Responsiveness Scale for Diagnosis of Severe Perinatal Hypoxia

Background: There are limitations to predicting perinatal asphyxia, as current tools rely almost entirely on fetal cardiotocography (CTG). The fetal lack of responsiveness scale (FLORS) is a new diagnostic alternative based on the physiological phenomena associated with fetal hypoxia. Objectives: The objective of this study was to develop, validate, and assess the diagnostic accuracy of the FLORS for predicting severe perinatal hypoxia (SPH). Study Design: A two-phase retrospective observational cross-sectional analytical study was conducted. Phase 1 involved the formulation and retrospective validation of the FLORS. A total of 366 fetal CTG records were evaluated twice by seven readers. Phase 2 was a collaborative, retrospective, multicenter diagnostic test study that included 37 SPH and 366 non-SPH cases. Results: Phase 1: A numeric, physiology-based scale was developed and refined based on expert opinions. The median time to apply the scale per reading was 38 s. Cronbach's alpha, which is a reliability measure, was significant (p = 0.784). The kappa index for test-retest agreement was moderate to reasonable, with a median value of 0.642. For interobserver agreement, the kappa index per variable was as follows: baseline, 0.669; accelerations, 0.658; variability, 0.467; late/variable decelerations, 0.638; slow response decelerations, 0.617; and trend to change, 0.423. Phase 2, including 37 SPH and 366 non-SPH cases, showed a sensitivity of 62.2% and specificity of 75.4% for the 2-point score, whereas the 3-point score had a sensitivity of 35.1% and specificity of 89.9%. The area under the curve (AUC) was significant at 0.73 (CI 0.645-0.818). Conclusions: FLORS demonstrated significant internal consistency and observer agreement, with a promising sensitivity-specificity balance and significant AUC. Further research is needed to assess its impact on perinatal hypoxia and cesarean delivery.

Risks Associated with Prolonged Latent Phase of Labor

OBJECTIVE

 We sought to assess the impact of a prolonged latent phase (PLP) on maternal and neonatal morbidity.

STUDY DESIGN

 This is a secondary analysis of a prospective cohort study conducted 2010 to 2015 that included all term gravidas who reached active labor (6 cm). Primary outcomes were composite maternal morbidity (maternal fever, postpartum hemorrhage, transfusion, endometritis, and severe perineal lacerations) and composite neonatal morbidity (respiratory distress syndrome, mechanical ventilation, birth injury, seizures, hypoxic ischemic encephalopathy, therapeutic hypothermia, or umbilical artery pH ≤ 7.1). Outcomes were compared between patients with and without PLP, defined as ≥90th percentile of labor duration between admission and active phase. Results were stratified by induction of labor (IOL) versus spontaneous labor. A stratified analysis was performed by mode of delivery. Multivariable logistic regression was used to adjust for confounders.

RESULTS

 In this cohort of 6,509 patients, 51% underwent IOL. A total of 650 patients had a PLP with a median length of 8.5 hours in spontaneous labor and 18.8 hours in IOL. Among patients with PLP, there was a significant increase in composite maternal morbidity with both IOL (adjusted odds ratio [aOR]: 1.36, 95% confidence interval [CI]: 1.01, 1.84) and spontaneous labor (aOR: 1.49, 95% CI: 1.09, 2.04) and an increase in composite neonatal morbidity with spontaneous labor only (aOR: 1.57, 95% CI: 1.01, 2.45). Cesarean delivery occurred more often in PLP group (14.0 vs. 25.1%). Among patients who underwent cesarean delivery, PLP remained associated with increased odds of maternal morbidity compared with those with normal latent phase.

CONCLUSION

 PLP at or above the 90th percentile in patients who reach active labor is associated with increased risk of maternal morbidity that is not mediated by cesarean delivery. PLP in spontaneous labor is associated with increased neonatal morbidity. These data suggest that further research is needed to establish latent phase cutoffs that may be incorporated into labor management guidelines.

KEY POINTS

· Latent labor ≥90th percentile is associated with increased maternal morbidity in induced and spontaneous labor.. · Latent labor ≥90th percentile in spontaneous but not induced labor is associated with increased neonatal morbidity.. · Cesarean delivery alone does not explain this increased maternal morbidity..

Correlation between total deceleration area in CTG records and cord blood pH in pregnancies with IUGR

PURPOSE

Fetal cardiotocography is the most common method to assess fetal well-being during labor. Nevertheless, its predictive ability for acidemia is limited, both in low-risk and high-risk pregnancies (Nelson et al. in N Engl J Med 334: 613-9, 1996; Rinciples P et al. in Health and Human Development Workshop Report on Electronic Fetal Monitoring : Update on Definitions. no. 2007, 510-515, 2008), especially in high-risk pregnancies, such as those complicated by growth restriction. In this study we aim examine the association between deceleration and acceleration areas and other measure of fetal heart rate in intrapartum fetal monitoring and neonatal arterial cord blood pH in pregnancies complicated by growth restriction.

MATERIALS AND METHODS

A retrospective cohort study of 100 deliveries complicated by growth restriction, delivered during 2018, was conducted. Known major fetal anomalies, non-vertex presentation and elective cesarean deliveries were excluded. Total deceleration and acceleration areas were calculated as the sum of the areas within the deceleration and acceleration, respectively.

RESULTS

In deliveries complicated by growth restriction, cord blood pH is significantly associated with total deceleration area (p = 0.05) and correlates with cumulative duration of the decelerations (Spearman's rank -0.363, p < 0.05), and total acceleration area (-0.358, p < 0.05). By comparing the cord blood pH in deliveries with a total deceleration area that was above and below the median total deceleration area, we demonstrated a significant difference between the categories.

CONCLUSIONS

Cord blood pH significantly correlates with total deceleration area and other fetal monitoring characteristics in neonates with growth restriction. Future studies using real-time, machine-learning based techniques of fetal heart rate monitoring, may provide population specific threshold values that will support bedside clinical decision making and perhaps achieve better outcomes.

The utility of fetal heart rate deceleration's descending slope in searching for a non-National Institute of Child Health and Human Development parameter for the detection of fetal acidosis

OBJECTIVE

To identify new parameters predicting fetal acidemia.

METHODS

A retrospective case-control study in a cohort of deliveries from a tertiary referral hospital-based cohort deliveries in Zaragoza, Spain between 2018 and 2021 was performed. To predict fetal acidemia, the NICHD categorizations and non-NICHD parameters were analyzed in the electronic fetal monitoring (EFM). Those included total reperfusion time, total deceleration area and the slope of the descending limb of the fetal heart rate of the last deceleration curve. The accuracy of the parameters was evaluated using the specificity for (80%, 85%, 90%, 95%) sensitivity and the area under the receiver operating characteristic curve (AUC).

RESULTS

A total of 10 362 deliveries were reviewed, with 224 cases and 278 controls included in the study. The NICHD categorizations showed reasonable discriminatory ability (AUC = 0.727). The non-NICHD parameters measured during the 30-min fetal monitoring, total deceleration area (AUC = 0.807, 95% CI: 0.770, 0.845) and total reperfusion time (AUC = 0.750, 95% CI: 0.707, 0.792), exhibited higher discriminatory ability. The slope of the descending limb of the fetal heart rate of the last deceleration curve had the best AUC value (0.853, 95% CI: 0.816, 0.889). The combination of total deceleration area or total reperfusion time with the slope demonstrated high discriminatory ability (AUC = 0.908, 95% CI: 0.882, 0.933; specificities of 71.6% and 72.7% for a sensitivity of 90%).

CONCLUSIONS

The slope of the descending limb of the fetal heart rate of the last deceleration curve is the strongest predictor of fetal acidosis, but its combination with the total reperfusion time shows better clinical utility.

The Impact of Cervical Effacement at Time of Amniotomy in Patients Undergoing Induction of Labor

OBJECTIVE

There is evidence to suggest that early amniotomy during induction of labor is advantageous. However, following cervical ripening balloon removal, the cervix remains less effaced and the utility of amniotomy in this setting is less clear. We investigated whether cervical effacement at the time of amniotomy impacts outcomes among nulliparas undergoing induction of labor.

STUDY DESIGN

This was a secondary analysis of a prospective cohort of singleton, term, nulliparous patients at a tertiary care center undergoing induction of labor and amniotomy. The primary outcome was completion of the first stage of labor. Secondary outcomes were vaginal delivery and postpartum hemorrhage. Outcomes were compared between patients with cervical effacement ≤50% (low effacement) and >50% (high effacement) at time of amniotomy. Multivariable logistic regression was used calculate risk ratios (RR) to adjust for confounders including cervical dilation. Stratified analysis was performed in patients with cervical ripening balloon use. A post hoc sensitivity analysis was performed to further control for cervical dilation.

RESULTS

Of 1,256 patients, 365 (29%) underwent amniotomy at low effacement. Amniotomy at low effacement was associated with reduced likelihood of completing the first stage (aRR: 0.87 [95% confidence interval, CI: 0.78-0.95]) and vaginal delivery (aRR: 0.87 [95% CI: 0.77-0.96]). Although amniotomy at low effacement was associated with lower likelihood of completing the first stage in all-comers, those who had amniotomy performed at low effacement following cervical ripening balloon expulsion were at the highest risk (aRR: 0.84 [95% CI: 0.69-0.98], p for interaction = 0.04) In the post hoc sensitivity analysis, including patients who underwent amniotomy at 3- or 4-cm dilation, low cervical effacement remained associated with a lower likelihood of completing the first stage of labor.

CONCLUSION

Low cervical effacement at time of amniotomy, particularly following cervical ripening balloon expulsion, is associated with a lower likelihood of successful induction.

KEY POINTS

· Low cervical effacement at amniotomy was associated with lower rates of complete dilation.. · Effacement at amniotomy is especially important for patients who had a cervical ripening balloon.. · Providers should consider cervical effacement when timing amniotomy for nulliparous term patients..

Umbilical Artery Cord Gas Abnormalities in the Presence of a Nuchal Cord in Term Singleton Pregnancies: A Cohort Study

OBJECTIVE

The clinical significance of nuchal cord (NC) at the time of delivery is unclear. Studies have found that NC is associated with lower umbilical artery (UA) pH. Since fetal hypercarbia precedes respiratory acidosis, we hypothesize UA pCO2 is elevated in neonates with NC at the time of delivery.

STUDY DESIGN

This is a secondary analysis of a prospective cohort study of women with full-term singleton pregnancies admitted in labor or for induction of labor at an institution with a universal umbilical cord gas policy. We compared patients with NC at the time of delivery to those without NC. Women were excluded if they did not have validated UA gases, had a major fetal anomaly, or had an intrauterine fetal demise. The primary outcome of the study was UA pCO2. Secondary outcomes were other components of UA gas and neonatal morbidity composite. Baseline characteristics were compared utilizing chi-square or Fisher's exact test or the Student's t-test. UA gas parameters were compared using the Kruskal-Wallis test. Multivariable logistic regression was utilized to adjust for confounders.

RESULTS

Of the 8,580 study participants, 7,608 had validated umbilical cord gases. The incidence of NC in the population was 24.15% (n = 1,837). UA pCO2 was higher in those with NC than without (58 mm Hg [53-64] vs. 55 mm Hg [50-60], p < 0.01). There was a greater odds of hypercarbia in the NC group (pCO2 > 65 mmHg; adjusted odds ratio [aOR]: 1.97, 95% confidence interval [CI]: 1.72-2.25, p < 0.01). Additionally, the NC group was more likely to be mildly acidemic (pH < 7.2, aOR: 1.74, 95% CI: 1.51-2.01, p < 0.01). There was no difference in composite neonatal morbidity between the groups.

CONCLUSION

NC is associated with an increased risk of hypercarbia and acidemia. However, this is not associated with increased risk of neonatal morbidity.

KEY POINTS

· Nuchal cord is associated with an increased risk of hypercarbia and mild acidemia.. · Nuchal cord is not likely associated with neonatal morbidity.. · Neonatal management should not be altered due to the presence of a nuchal cord at delivery..

The Correlation Between the Total Decelerations and Accelerations Areas and Cord Blood pH in Women with Low-Risk Pregnancies

Fetal acidosis among low-risk pregnancies is not common; however, identifying those at risk for this complication antenatally is of great interest. We aimed to assess the correlation between the total decelerations area during the last 120 min of fetal monitoring prior to delivery and neonatal acidemia in low-risk pregnancies and whether the total acceleration area has a protective effect in the presence of decelerations. A retrospective cohort study was conducted among women with term low-risk pregnancies. A researcher blinded to fetal outcomes interpreted electronic fetal monitor patterns during the 120 min prior to delivery. The primary outcome was fetal acidemia, defined as umbilical artery pH below 7.10. The correlation between the total decelerations and accelerations areas and cord blood pH was tested using the Spearman correlation coefficient. A total of 109 women were included and of these, six (5.5%) delivered infants with cord blood pH < 7.10. A significant correlation was demonstrated between the total decelerations area and cord blood pH (p = 0.01). No correlation was found between the total accelerations area and cord blood pH. Among low-risk pregnancies, a correlation was found between the total decelerations area but not the total accelerations area during the final 120 min of labor and cord blood pH.

Labor management and neonatal outcomes in cardiotocography categories II and III (Review)

The safe care of both mothers and fetuses during labor is a primary goal of all health professionals. The assessment of fetal oxygenation and well-being is a key aspect of perinatal care provided. Fetal heart rate (FHR) auscultation became part of daily obstetric practice in a number of countries during the 20th century and remains a key method of fetal monitoring, particularly in low-risk pregnancies. Cardiotocography (CTG) is the continuous monitoring and recording of the FHR and uterine myometrial activity, making it possible to assess the fetal condition. It therefore plays a critical role in the detection of fetal hypoxia during labor, a condition directly related to short- and long-term complications in the newborn. Herein, particular reference is made to the management of CTG category II and III standards, as well as to the handling of childbirth. In addition, specific FHR patterns are associated with immediate neonatal outcomes based on updated studies conducted worldwide. Finally, the prognostic significance of CTG and its potential as a prospective avenue for further investigation are also highlighted herein. Given that the misinterpretation of CTG findings is the most common cause of medical-legal responsibility, this knowledge field requires more emphasis and attention. The aim of the present review was to further deepen the knowledge on issues that mainly concern the safety and monitoring of pregnant women and fetuses during childbirth.

The Correlation between Fetal Monitor Decelerations Area and Neonatal Cord pH among Preeclamptic parturient: an Automated Approach to a Clinical Challenge

OBJECTIVE

 To examine whether a correlation exists between electronic fetal monitoring (EFM) in the final 120 minute prior to delivery and neonatal cord blood pH among parturients with preeclampsia.

STUDY DESIGN

 A retrospective cohort study of parturients with term and near-term preeclampsia who delivered at Soroka University Medical Center between 2013 and 2020 was conducted. EFM tracings, demographical data, and obstetrical outcomes were retrieved from the patients' electronic medical records. Using MATLAB program, area under the curve (AUC) measurements were applied. Correlation was calculated using the Spearman's correlation coefficient.

RESULTS

 EFM of 88 parturients with preeclampsia were assessed. A significant negative correlation was demonstrated between cord blood pH and the decelerations AUC, total decelerations duration, and deceleration depth. No correlation was demonstrated between area over the curve (acceleration) and cord blood pH. In a multivariate linear regression, total deceleration AUC was found independently negatively associated with cord blood pH (beta = -0.264, p = 0.011) controlling for second stage of labor duration and induction of labor.

CONCLUSION

 Among parturients with preeclampsia, EFM indices may assist in the diagnosis of fetal acidemia. Further studies are needed to strengthen and establish the use of electronic EFM in the management of labor and delivery.

KEY POINTS

· A negative correlation was demonstrated between cord blood pH and the decelerations AUC.. · Total deceleration AUC was found independently negatively associated.. · Among parturients with preeclampsia, EFM indices may assist in the diagnosis of fetal acidemia..

Intrapartum electronic fetal heart rate monitoring to predict acidemia at birth with the use of deep learning

BACKGROUND

Electronic fetal monitoring is used in most US hospital births but has significant limitations in achieving its intended goal of preventing intrapartum hypoxic-ischemic injury. Novel deep learning techniques can improve complex data processing and pattern recognition in medicine.

OBJECTIVE

This study aimed to apply deep learning approaches to develop and validate a model to predict fetal acidemia from electronic fetal monitoring data.

STUDY DESIGN

The database was created using intrapartum electronic fetal monitoring data from 2006 to 2020 from a large, multisite academic health system. Data were divided into training and testing sets with equal distribution of acidemic cases. Several different deep learning architectures were explored. The primary outcome was umbilical artery acidemia, which was investigated at 4 clinically meaningful thresholds: 7.20, 7.15, 7.10, and 7.05, along with base excess. The receiver operating characteristic curves were generated with the area under the receiver operating characteristic assessed to determine the performance of the models. External validation was performed using a publicly available Czech database of electronic fetal monitoring data.

RESULTS

A total of 124,777 electronic fetal monitoring files were available, of which 77,132 had <30% missingness in the last 60 minutes of the electronic fetal monitoring tracing. Of these, 21,041 were matched to a corresponding umbilical cord gas result, of which 10,182 were time-stamped within 30 minutes of the last electronic fetal monitoring reading and composed the final dataset. The prevalence rates of the outcomes in the data were 20.9% with a pH of <7.2, 9.1% with a pH of <7.15, 3.3% with a pH of <7.10, and 1.3% with a pH of <7.05. The best performing model achieved an area under the receiver operating characteristic of 0.85 at a pH threshold of <7.05. When predicting the joint outcome of both pH of <7.05 and base excess of less than -10 meq/L, an area under the receiver operating characteristic of 0.89 was achieved. When predicting both pH of <7.20 and base excess of less than -10 meq/L, an area under the receiver operating characteristic of 0.87 was achieved. At a pH of <7.15 and a positive predictive value of 30%, the model achieved a sensitivity of 90% and a specificity of 48%.

CONCLUSION

The application of deep learning methods to intrapartum electronic fetal monitoring analysis achieves promising performance in predicting fetal acidemia. This technology could help improve the accuracy and consistency of electronic fetal monitoring interpretation.

Intrapartum fetal heart rate monitoring: Rationalise, refine or replace?

Monitoring the fetal heartbeat underpins assessment of fetal wellbeing in labour. Although commonly employed in clinical practice, shortcomings remain. A recent review of clinical practice guidelines highlights the variation in definitions of the fetal heart rate that will lead to differences in interpretation. Will intrapartum care be improved by greater consensus around clinical practice guidelines through rationalisation or refinement of guidelines, or will the future see this technique replaced by more accurate forms of fetal monitoring?

The relationship between maternal anemia and electronic fetal monitoring patterns

BACKGROUND

Anemia is a commonly diagnosed comorbidity in pregnancy that is associated with increased risk of maternal and neonatal complications. Recent data demonstrate that maternal anemia is associated with higher umbilical artery and umbilical vein O2 content at the time of delivery.

OBJECTIVE

This study aimed to examine the relationship between maternal anemia and electronic fetal monitoring patterns associated with fetal hypoxia.

STUDY DESIGN

This is a secondary analysis of a prospective cohort study of singleton term deliveries with cord gases and universal complete blood count collected on admission between 2010 and 2014. Maternal anemia was defined as hemoglobin ≤11.0 g/dL on admission. The primary outcome was a composite of high-risk category 2 electronic fetal monitoring features in the last 60 minutes before delivery (recurrent late and/or variable decelerations, minimal variability, tachycardia, or >1 prolonged deceleration); secondary outcomes were total deceleration area and total deceleration area >90th percentile. Of the 8580 patients in the original study, 8196 were included in the analysis. Outcomes were compared between patients with and without anemia. Multivariable logistic regression was used to adjust for potentially confounding factors, including hypertensive disorders of pregnancy and induction of labor.

RESULTS

Of the 8196 patients with complete blood count on admission and fetal monitoring data, 2672 (32.6%; 2672/8196) were anemic and 5524 (67.4%; 5524/8196) were not. Patients with anemia were significantly less likely to have composite high-risk category 2 features on electronic fetal monitoring (34.2% vs 32.0%; adjusted risk ratio, 0.93; 95% confidence interval, 0.86-0.99). Women with anemia also had decreased total deceleration area and were less likely to have total deceleration area >90th percentile (18.7% vs 16.2%; adjusted risk ratio, 0.85; 95% confidence interval, 0.77-0.94).

CONCLUSION

Patients with anemia are less likely to have high-risk category 2 electronic fetal monitoring features associated with fetal hypoxia. This finding is consistent with the association between maternal anemia and increased umbilical cord O2 content, and suggests that maternal anemia may be protective against intrapartum fetal hypoxia.

Three-tiered fetal heart rate interpretation system and adverse neonatal and maternal outcomes: a systematic review and meta-analysis

OBJECTIVE

This study aimed to evaluate the rate of adverse neonatal or maternal outcomes in parturients with fetal heart rate tracings categorized as I, II or, III within the last 30 to 120 minutes of delivery.

DATA SOURCES

The MEDLINE Ovid, Scopus, Embase, CINAHL, and Clinicaltrials.gov databases were searched electronically up to May 2022, using combinations of the relevant medical subject heading terms, keywords, and word variants that were considered suitable for the topic.

STUDY ELIGIBILITY CRITERIA

Only observational studies of term infants reporting outcomes of interest with category I, II, or III fetal heart rate tracings were included.

STUDY APPRAISAL AND SYNTHESIS METHODS

The coprimary outcome was the rate of either Apgar score <7 at 5 minutes or umbilical artery pH <7.00. Secondary outcomes were divided into neonatal and maternal adverse outcomes. Quality assessment of the included studies was performed using the Newcastle-Ottawa Scale. Random-effect meta-analyses of proportions were used to estimate the pooled rates of each categorical outcome in fetal heart rate tracing category I, II, and III patterns, and random-effect head-to-head meta-analyses were used to directly compare fetal heart rate tracings category I vs II and fetal heart rate tracing category II vs III, expressing the results as summary odds ratio or as mean differences with relative 95% confidence intervals.

RESULTS

Of the 671 articles reviewed, 3 publications met the inclusion criteria. Among them were 47,648 singletons at ≥37 weeks' gestation. Fetal heart rate tracings in the last 30 to 120 minutes before delivery were characterized in the following manner: 27.0% of deliveries had category I tracings, 72.9% had category II tracings, and 0.1% had category III tracings. A single study, which was rated to be of poor quality, contributed 82.1% of the data and it did not provide any data for category III fetal heart rate tracings. When compared with category I fetal heart rate tracings (0.74%), the incidence of an Apgar score <7 at 5 minutes were significantly higher among deliveries with category II fetal heart rate tracings (1.51%) (odds ratio, 1.56; 95% confidence interval, 1.23-1.99) and among those with category III tracings (14.63%) (odds ratio, 14.46; 95% confidence interval, 2.77-75.39). When compared with category II tracings, category III tracings also had a significantly higher likelihood of a low Apgar score at 5 minutes (odds ratio, 14.46; 95% confidence interval, 2.77-75.39). The incidence of an umbilical artery pH <7.00 were similar among those with category I and those with category II tracings (0.08% vs 0.24%; odds ratio, 2.85; 95% confidence interval, 0.41-19.55). When compared with category I tracings, the incidence of an umbilical artery pH <7.00 was significantly more common among those with category III tracings (31.04%; odds ratio, 161.56; 95% confidence interval, 25.18-1036.42); likewise, when compared with those with category II tracings, those with category III tracings had a significantly higher likelihood of having an umbilical artery pH <7.00 (odds ratio, 42.29; 95% confidence interval, 14.29-125.10). Hypoxic-ischemic encephalopathy occurred with similar frequency among those with categories I and those with category II tracings (0 vs 0.81%; odds ratio, 5.86; 95% confidence interval, 0.75-45.89) but was significantly more common among those with category III tracings (0 vs 18.97%; odds ratio, 61.43; 95% confidence interval, 7.49-503.50). Cesarean delivery occurred with similar frequency among those with category I (13.41%) and those with category II tracings (11.92%) (odds ratio, 0.87; 95% confidence interval, 0.72-1.05) but was significantly more common among those with with category III tracings (14.28%) (odds ratio, 3.97; 95% confidence interval, 1.62-9.75). When compared with those with category II tracings, cesarean delivery was more common among those with category III tracings (odds ratio, 4.55; 95% confidence interval, 1.88-11.01).

CONCLUSION

Although the incidence of an Apgar score <7 at 5 minutes and umbilical artery pH <7.00 increased significantly with increasing fetal heart rate tracing category, about 98% of newborns with category II tracings do not have these adverse outcomes. The 3-tiered fetal heart rate tracing interpretation system provides an approximate but imprecise measurement of neonatal prognosis.

Intrapartum electronic fetal monitoring features associated with a clinical diagnosis of nonreassuring fetal status

BACKGROUND

Nonreassuring fetal status detected by continuous electronic fetal monitoring accounts for almost 1 in 4 primary cesarean deliveries. However, given the subjective nature of the diagnosis, there is a need to identify the electronic fetal monitoring patterns that are clinically considered nonreassuring.

OBJECTIVE

This study aimed to describe which electronic fetal monitoring features are most commonly associated with first-stage cesarean delivery for nonreassuring fetal status, and to evaluate the risk of neonatal acidemia following cesarean delivery for nonreassuring fetal status.

STUDY DESIGN

This was a nested case-control study in a prospectively collected cohort of patients with singleton pregnancies at ≥37 weeks' gestation, admitted in spontaneous labor or for induction of labor from 2010 to 2014 at a single tertiary care center. Patients with preterm pregnancies, multiple gestations, planned cesarean delivery, or nonreassuring fetal status in the second stage of labor were excluded. Cases were identified as having nonreassuring fetal status on the basis of what was documented in the operative note by the delivering physician. Controls were patients without nonreassuring fetal status within 1 hour of delivery. Cases were matched to controls in a 1:2 ratio by parity, obesity, and history of cesarean delivery. Electronic fetal monitoring data were abstracted by credentialed obstetrical research nurses for the 60 minutes before delivery. The primary exposure of interest was the incidence of high-risk category II electronic fetal monitoring features in the 60 minutes before delivery; in particular, the incidence of minimal variability, recurrent late decelerations, recurrent variable decelerations, tachycardia, and >1 prolonged deceleration were compared between groups. We also compared neonatal outcomes between cases and controls, including fetal acidemia (umbilical artery pH <7.1), other umbilical artery gas analytes, and neonatal and maternal outcomes.

RESULTS

Of the 8580 patients in the parent study, 714 (8.3%) underwent cesarean delivery for nonreassuring fetal status in the first stage of labor. Patients diagnosed with nonreassuring fetal status requiring cesarean delivery were more likely to have recurrent late decelerations, >1 prolonged deceleration, and recurrent variable decelerations compared with controls. More than 1 prolonged deceleration was associated with 6 times increased rate of nonreassuring fetal status diagnosis resulting in cesarean delivery (adjusted odds ratio, 6.73 [95% confidence interval, 2.47-8.33]). Rates of fetal tachycardia were similar between groups. Minimal variability was less common in the nonreassuring fetal status group compared with controls (adjusted odds ratio, 0.36 [95% confidence interval, 0.25-0.54]). Compared with control deliveries, cesarean delivery for nonreassuring fetal status was associated with nearly 7 times higher risk of neonatal acidemia (7.2% vs 1.1%; adjusted odds ratio, 6.93 [95% confidence interval, 3.83-12.54]). Composite neonatal morbidity and composite maternal morbidity were more likely among patients delivered for nonreassuring fetal status in the first stage (3.9% vs 1.1%; adjusted odds ratio, 5.70 [2.60-12.49]; and 13.3% vs 8.0%; adjusted odds ratio, 1.99 [1.41-2.80]).

CONCLUSION

Although multiple category II electronic fetal monitoring features have been traditionally linked to acidemia, the presence of recurrent late decelerations, recurrent variable decelerations, and prolonged decelerations seemed to concern obstetricians enough to surgically intervene for nonreassuring fetal status. A clinical intrapartum diagnosis of nonreassuring fetal status in the setting of these electronic fetal monitoring features is also associated with increased risk of acidemia, suggesting clinical validity to the diagnosis of nonreassuring fetal status.

The association of intrapartum deceleration and acceleration areas with MRI findings in neonatal encephalopathy

BACKGROUND

Hypoxic-ischemic encephalopathy (HIE) is an important contributor to disability worldwide. The current cardiotocography (CTG) predictive value for neonatal outcome is limited.

OBJECTIVE

To assess the association of intrapartum CTG deceleration and acceleration areas with early MRI cerebral pathology in infants with HIE.

METHODS

Term and near-term low-risk pregnancies that resulted in HIE, treated with therapeutic hypothermia with sufficient CTG records from a single, tertiary hospital between 2013 and 2021 were enrolled. Accelerations and decelerations areas, their minimum and maximum depths, and duration were calculated as well as the acceleration-to-deceleration area ratio during the 120 min prior to delivery. These data were assessed for associations with higher degrees of abnormality on early MRI scans.

RESULTS

A total of 77 infants were included in the final analysis. Significant associations between increased total acceleration area (p = 0.007) and between a higher acceleration-to-deceleration area ratio (p = 0.003) and better MRI results were detected.

CONCLUSION

In neonates treated for HIE, acceleration area and acceleration-to-deceleration ratio are associated with the risk of neonatal brain MRI abnormalities. To increase the role of these measurements as a relevant clinical tool, larger, more powered prospective trials are needed, using computerized real-time analysis.

IMPACT

The current cardiotocography predictive value for neonatal outcome is limited. This study aimed to assess the association of intrapartum deceleration and acceleration areas with the degree of cerebral injury in early cerebral MRI of neonates with encephalopathy. Lower acceleration area and acceleration-to-deceleration ratio were found to be associated with a higher degree of neonatal brain injury. Brain MRI is a marker of long-term outcome; its association with cardiotocography indices supports their association with long-term outcome in these neonates. Future computer-based CTG area analysis could assist in delivery room decision making to better time interventions and prevent hypoxic-ischemic encephalopathy.

Pathophysiological interpretation of fetal heart rate tracings in clinical practice

The onset of regular, strong, and progressive uterine contractions may result in both mechanical (compression of the fetal head and/or umbilical cord) and hypoxic (repetitive and sustained compression of the umbilical cord or reduction in uteroplacental oxygenation) stresses to a human fetus. Most fetuses are able to mount effective compensatory responses to avoid hypoxic-ischemic encephalopathy and perinatal death secondary to the onset of anaerobic metabolism within the myocardium, culminating in myocardial lactic acidosis. In addition, the presence of fetal hemoglobin, which has a higher affinity for oxygen even at low partial pressures of oxygen than the adult hemoglobin, especially increased amounts of fetal hemoglobin (ie, 180-220 g/L in fetuses vs 110-140 g/L in adults), helps the fetus to withstand hypoxic stresses during labor. Different national and international guidelines are currently being used for intrapartum fetal heart rate interpretation. These traditional classification systems for fetal heart rate interpretation during labor are based on grouping certain features of fetal heart rate (ie, baseline fetal heart rate, baseline variability, accelerations, and decelerations) into different categories (eg, category I, II, and III tracings, "normal, suspicious, and pathologic" or "normal, intermediary, and abnormal"). These guidelines differ from each other because of the features included within different categories and because of their arbitrary time limits stipulated for each feature to warrant an obstetrical intervention. This approach fails to individualize care because the "ranges of normality" for stipulated parameters apply to the population of human fetuses and not to the individual fetus in question. Moreover, different fetuses have different reserves and compensatory responses and different intrauterine environments (presence of meconium staining of amniotic fluid, intrauterine inflammation, and the nature of uterine activity). Pathophysiological interpretation of fetal heart rate tracing is based on the application of the knowledge of fetal responses to intrapartum mechanical and/or hypoxic stress in clinical practice. Both experimental animal studies and observational human studies suggest that, just like adults undertaking a treadmill exercise, human fetuses show predictable compensatory responses to a progressively evolving intrapartum hypoxic stress. These responses include the onset of decelerations to reduce myocardial workload and preserve aerobic metabolism, loss of accelerations to abolish nonessential somatic body movements, and catecholamine-mediated increases in the baseline fetal heart rate and effective redistribution and centralization to protect the fetal central organs (ie, the heart, brain, and adrenal glands), which are essential for intrauterine survival. Moreover, it is essential to incorporate the clinical context (progress of labor, fetal size and reserves, presence of meconium staining of amniotic fluid and intrauterine inflammation, and fetal anemia) and understand the features suggestive of fetal compromise in nonhypoxic pathways (eg, chorioamnionitis and fetomaternal hemorrhage). It is important to appreciate that the timely recognition of the speed of onset of intrapartum hypoxia (ie, acute, subacute, and gradually evolving) and preexisting uteroplacental insufficiency (ie, chronic hypoxia) on fetal heart rate tracing is crucial to improve perinatal outcomes.

Optimizing the management of acute, prolonged decelerations and fetal bradycardia based on the understanding of fetal pathophysiology

Any acute and profound reduction in fetal oxygenation increases the risk of anaerobic metabolism in the fetal myocardium and, hence, the risk of lactic acidosis. On the contrary, in a gradually evolving hypoxic stress, there is sufficient time to mount a catecholamine-mediated increase in the fetal heart rate to increase the cardiac output and redistribute oxygenated blood to maintain an aerobic metabolism in the fetal central organs. When the hypoxic stress is sudden, profound, and sustained, it is not possible to continue to maintain central organ perfusion by peripheral vasoconstriction and centralization. In case of acute deprivation of oxygen, the immediate chemoreflex response via the vagus nerve helps reduce fetal myocardial workload by a sudden drop of the baseline fetal heart rate. If this drop in the fetal heart rate continues for >2 minutes (American College of Obstetricians and Gynecologists' guideline) or 3 minutes (National Institute for Health and Care Excellence or physiological guideline), it is termed a prolonged deceleration, which occurs because of myocardial hypoxia, after the initial chemoreflex. The revised International Federation of Gynecology and Obstetrics guideline (2015) considers the prolonged deceleration to be a "pathologic" feature after 5 minutes. Acute intrapartum accidents (placental abruption, umbilical cord prolapse, and uterine rupture) should be excluded immediately, and if they are present, an urgent birth should be accomplished. If a reversible cause is found (maternal hypotension, uterine hypertonus or hyperstimulation, and sustained umbilical cord compression), immediate conservative measures (also called intrauterine fetal resuscitation) should be undertaken to reverse the underlying cause. In reversible causes of acute hypoxia, if the fetal heart rate variability is normal before the onset of deceleration, and normal within the first 3 minutes of the prolonged deceleration, then there is an increased likelihood of recovery of the fetal heart rate to its antecedent baseline within 9 minutes with the reversal of the underlying cause of acute and profound reduction in fetal oxygenation. The continuation of the prolonged deceleration for >10 minutes is termed "terminal bradycardia," and this increases the risk of hypoxic-ischemic injury to the deep gray matter of the brain (the thalami and the basal ganglia), predisposing to dyskinetic cerebral palsy. Therefore, any acute fetal hypoxia, which manifests as a prolonged deceleration on the fetal heart rate tracing, should be considered an intrapartum emergency requiring an immediate intervention to optimize perinatal outcome. In uterine hypertonus or hyperstimulation, if the prolonged deceleration persists despite stopping the uterotonic agent, then acute tocolysis is recommended to rapidly restore fetal oxygenation. Regular clinical audit of the management of acute hypoxia, including the "the onset of bradycardia to delivery interval," may help identify organizational and system issues, which may contribute to poor perinatal outcomes.

Fetal defenses against intrapartum head compression-implications for intrapartum decelerations and hypoxic-ischemic injury

Uterine contractions during labor and engagement of the fetus in the birth canal can compress the fetal head. Its impact on the fetus is unclear and still controversial. In this integrative physiological review, we highlight evidence that decelerations are uncommonly associated with fetal head compression. Next, the fetus has an impressive ability to adapt to increased intracranial pressure through activation of the intracranial baroreflex, such that fetal cerebral perfusion is well-maintained during labor, except in the setting of prolonged systemic hypoxemia leading to secondary cardiovascular compromise. Thus, when it occurs, fetal head compression is not necessarily benign but does not seem to be a common contributor to intrapartum decelerations. Finally, the intracranial baroreflex and the peripheral chemoreflex (the response to acute hypoxemia) have overlapping efferent effects. We propose the hypothesis that these reflexes may work synergistically to promote fetal adaptation to labor.

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 2.5 min for 4 h or until arterial pressure fell below 20 mmHg. 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 20 s of UCOs, but FHR during the final 40 s 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.

The Impact of Total Deceleration Area and Fetal Growth on Neonatal Acidemia in Vacuum Extraction Deliveries

We aimed to investigate the correlation between total deceleration area (TDA), neonatal birthweight and neonatal acidemia in vacuum extractions (VEs). This is a retrospective study in a tertiary hospital, including VE performed due to non-reassuring fetal heart rate (NRFHR). Electronic fetal monitoring during the 120 min preceding delivery was interpreted by two obstetricians who were blinded to neonatal outcomes. TDA was calculated as the sum of the area under the curve for each deceleration. Neonatal birthweights were classified as low (<2500 g), normal (2500-3999 g) or macrosomic (>4000 g). A total of 85 VEs were analyzed. Multivariable linear regression, adjusted for gestational age, nulliparity and diabetes mellitus, revealed a negative correlation between TDA in the 60 min preceding delivery and umbilical cord pH. For every 10 K increase in TDA, the cord pH decreased by 0.02 (p = 0.038; 95%CI, -0.05-0.00). The use of the Ventouse-Mityvac cup was associated with a 0.08 decrease in cord pH as compared to the Kiwi OmniCup (95%CI, -0.16-0.00; p = 0.049). Low birthweights, compared to normal birthweights, were not associated with a change in cord pH. To conclude, a significant correlation was found between TDA during the 60 min preceding delivery and cord pH in VE performed due to NRFHR.

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.

Fetal heart rate responses in chronic hypoxaemia with superimposed repeated hypoxaemia consistent with early labour: a controlled study in fetal sheep

OBJECTIVE

Deceleration area (DA) and capacity (DC) of the fetal heart rate can help predict risk of intrapartum fetal compromise. However, their predictive value in higher risk pregnancies is unclear. We investigated whether they can predict the onset of hypotension during brief hypoxaemia repeated at a rate consistent with early labour in fetal sheep with pre-existing hypoxaemia.

DESIGN

Prospective, controlled study.

SETTING

Laboratory.

SAMPLE

Chronically instrumented, unanaesthetised near-term fetal sheep.

METHODS

One-minute complete umbilical cord occlusions (UCOs) were performed every 5 minutes in fetal sheep with baseline p_a O₂ <17 mmHg (hypoxaemic, n = 8) and >17 mmHg (normoxic, n = 11) for 4 hours or until arterial pressure fell <20 mmHg.

MAIN OUTCOME MEASURES

DA, DC and arterial pressure.

RESULTS

Normoxic fetuses showed effective cardiovascular adaptation without hypotension and mild acidaemia (lowest arterial pressure 40.7 ± 2.8 mmHg, pH 7.35 ± 0.03). Hypoxaemic fetuses developed hypotension (lowest arterial pressure 20.8 ± 1.9 mmHg, P < 0.001) and acidaemia (final pH 7.07 ± 0.05). In hypoxaemic fetuses, decelerations showed faster falls in FHR over the first 40 seconds of UCOs but the final deceleration depth was not different to normoxic fetuses. DC was modestly higher in hypoxaemic fetuses during the penultimate (P = 0.04) and final (P = 0.012) 20 minutes of UCOs. DA was not different between groups.

CONCLUSION

Chronically hypoxaemic fetuses had early onset of cardiovascular compromise during labour-like brief repeated UCOs. DA was unable to identify developing hypotension in this setting, while DC only showed modest differences between groups. These findings highlight that DA and DC thresholds need to be adjusted for antenatal risk factors, potentially limiting their clinical utility.

Intrapartum deceleration and acceleration areas are associated with neonatal encephalopathy

OBJECTIVE

To investigate whether an association exists between deceleration and acceleration areas on continuous fetal cardiotocography (CTG) and neonatal encephalopathy (NE).

METHODS

A single center, retrospective case-control study was conducted to compare CTG characteristics of low-risk pregnancies (35 weeks of gestation or more), complicated by moderate to severe NE with two matched controls for every case. Controls were matched by gestational age and cord blood pH. We analyzed the intrapartum CTG recordings by calculation of the deceleration and acceleration areas and the ratio between the two.

RESULTS

During the period between 2013 and 2019, we identified 95 cases of low-risk pregnancies that were complicated by moderate to severe NE in our center. Thirty-three (34.7%) deliveries were excluded, mostly because of an insufficient duration of the CTG recordings. The remaining 62 cases were matched with 123 controls. We found that NE was significantly associated with an increased total deceleration area, a decreased total acceleration area, and a lower acceleration-to-deceleration ratio.

CONCLUSIONS

NE was significantly associated with increased total deceleration area, decreased total acceleration area, and a lower acceleration-to-deceleration ratio, independent of cord blood pH. Development of a computerized real-time analysis of fetal heart rate tracings may contribute to making these measurements a more valid clinical tool.

Integrated Deep Learning and Supervised Machine Learning Model for Predictive Fetal Monitoring

Asphyxiation associated with metabolic acidosis is one of the common causes of fetal deaths. The paper aims to develop a feature extraction and prediction algorithm capable of identifying most of the features in the SISPORTO software package and late and variable decelerations. The resulting features were used for classification based on umbilical cord pH data. The algorithms developed here were used to predict cord pH levels. The prediction system assists the obstetricians in assessing the state of the fetus better than the category methods, as only about 30% of the patients in the pathological category suffer from acidosis, while the majority of acidotic babies were in the suspect category, which is considered lower risk. By predicting the direct indicator of acidosis, umbilical cord pH, this work demonstrates a methodology, which uses fetal heart rate and uterine activity, to identify acidosis. This paper introduces a forecasting model based on deep learning to predict heart rate and uterine contractions, integrated with the classification algorithm, resulting in a robust tool for predictive fetal monitoring. The hybrid algorithm resulted in a model capable of providing future conditions of the fetus, which obstetricians can use for diagnosis and planning interventions. The ensemble classification algorithm had a test accuracy of 85% (n = 24) in predicting fetal acidosis on the features extracted from the cardiotocography data. When integrated with the classification model, the results from the prediction model (long short-term memory network) can effectively identify fetal acidosis 2 or 4 min in the future.

Increased variability of fetal heart rate during labour: a review of preclinical and clinical studies

Increased fetal heart rate variability (FHRV) in intrapartum cardiotocographic recording has been variably defined and poorly understood, limiting its clinical utility. Both preclinical (animal) and clinical (human) evidence support that increased FHRV is observed in the early stage of intrapartum fetal hypoxaemia but can also be observed in a subset of fetuses during the preterminal stage of repeated hypoxaemia. This review of available evidence provides data and expert opinion on the pathophysiology of increased FHRV, its clinical significance and a stepwise approach regarding the management of this pattern, and propose recommendations for standardisation of related terminology.

Approaches to Preventing Intrapartum Fetal Injury

Electronic fetal monitoring (EFM) was introduced into obstetric practice in 1970 as a test to identify early deterioration of fetal acid-base balance in the expectation that prompt intervention ("rescue") would reduce neonatal morbidity and mortality. Clinical trials using a variety of visual or computer-based classifications and algorithms for intervention have failed repeatedly to demonstrate improved immediate or long-term outcomes with this technique, which has, however, contributed to an increased rate of operative deliveries (deemed "unnecessary"). In this review, we discuss the limitations of current classifications of FHR patterns and management guidelines based on them. We argue that these clinical and computer-based formulations pay too much attention to the detection of systemic fetal acidosis/hypoxia and too little attention not only to the pathophysiology of FHR patterns but to the provenance of fetal neurological injury and to the relationship of intrapartum injury to the condition of the newborn. Although they do not reliably predict fetal acidosis, FHR patterns, properly interpreted in the context of the clinical circumstances, do reliably identify fetal neurological integrity (behavior) and are a biomarker of fetal neurological injury (separate from asphyxia). They provide insight into the mechanisms and trajectory (evolution) of any hypoxic or ischemic threat to the fetus and have particular promise in signaling preventive measures (1) to enhance the outcome, (2) to reduce the frequency of "abnormal" FHR patterns that require urgent intervention, and (3) to inform the decision to provide neuroprotection to the newborn.

Optimal duration of cardiotocography assessment using the iPREFACE score to predict fetal acidemia

Cardiotocography (CTG) applicability to improve fetal outcomes remains controversial. This study aimed to determine the clinically optimal CTG assessment duration using the integrated score index to predict fetal acidemia by intrapartum fetal heart rate monitoring (iPREFACE score). This single-center, retrospective observational study included 325 normal full-term singleton vaginal deliveries at the Toho University Omori Medical Center, from September 2018 to March 2019. The iPREFACE(10), iPREFACE(30), and iPREFACE(60) scores were calculated at 10, 30, and 60 min immediately before delivery. The primary outcome was fetal acidemia (umbilical artery blood pH < 7.2). The secondary outcome was the correlation between all iPREFACE scores and the umbilical artery blood pH, base excess (BE), and lactate values. Patients without accurate CTG findings or with failure of umbilical artery blood sampling immediately after birth were excluded, leaving 145 patients in the final analysis. Of these, 16, three, and two had umbilical artery blood pH of < 7.2, < 7.1, and < 7.0, respectively. All iPREFACE scores significantly correlated with umbilical artery blood pH, BE, and lactate values. iPREFACE(30) had the highest predictive capacity for fetal acidemia, suggesting that 30 min immediately before delivery may be a useful scoring time in clinical practice.

Heart rate markers for prediction of fetal acidosis in an experimental study on fetal sheep

To overcome the difficulties in interpreting fetal heart rate (FHR), several tools based on the autonomic nervous system and heart rate variability (HRV) have been developed. The objective of this study was to use FHR and HRV parameters for the prediction of fetal hypoxia. It was an experimental study in the instrumented fetal sheep. Repeated umbilical cord occlusions were performed to achieve severe acidosis. Hemodynamic parameters, ECG, and blood gases were analyzed. The variables used were heart rate baseline, HRV analysis (RMSSD, SDNN, LF, HF, HFnu, Fetal Stress Index (FSI), …), and morphological analysis of decelerations. The gold standard used to classify hypoxia was the fetal arterial pH (pH < 7.10). Different multivariable statistical methods (logistic regression and decision trees) were applied for the detection of acidosis. 21 lambs were instrumented. A total of 130 pairs of FHR/fetal pH analysis were obtained of which 29 in the acidosis group and 101 in the non-acidosis group. After logistic regression model with bootstrap resampling and stepwise backward selection, only one variable was selected, FSI. The AUC of FSI alone in this model was 0.81 with a sensitivity of 0.66, specificity of 0.88, PPV of 0.61, and NPV of 0.90 considering a threshold of 68. Decision trees with CHAID and CART algorithms showed a sensitivity of 0.48 and 0.59, respectively, and a specificity of 0.94 for both. All employed methods identified HRV variables as the most predictive of acidosis. The primary variables selected automatically were those from the HRV. Supporting the use of FHRV measures for the screening of fetal acidosis during labour is interesting.

Correlation between total deceleration area and fetal cord blood pH in neonates complicated with meconium-stained amniotic fluid at term

OBJECTIVE

To assess the correlation between total area under the Curve (AUC) of decelerations and accelerations and neonatal acidemia in pregnancies complicated with meconium-stained amniotic fluid (MSAF).

METHODS

A retrospective cohort study was conducted among women who delivered with a diagnosis of MSAF. Electronic fetal monitoring (EFM) patterns 120 min before delivery were interpreted by a researcher blinded to fetal outcomes. The primary outcome was fetal acidemia, defined as umbilical artery pH below 7.10. The correlation was tested using the Spearman correlation coefficient.

RESULTS

A total of 102 women were included; 24 delivered infants with cord blood pH < 7.20, and only five delivered infants with cord blood pH < 7.10. A significant correlation was demonstrated between total AUC of decelerations and accelerations and cord blood pH (P = 0.02). A sub-analysis according to gestational age at delivery (up to and beyond 40 weeks) was conducted. A significant correlation was demonstrated (P = 0.02) only in the term group(n = 37).

CONCLUSION

A correlation was demonstrated between total AUC of decelerations and accelerations and cord blood pH in neonates with MSAF. This correlation was significant for neonates delivered before 40 weeks of gestation, but not for those delivered after 40 weeks of gestation.

Severity of intrapartum fever and neonatal outcomes

BACKGROUND

The few studies that have addressed the relationship between severity of intrapartum fever and neonatal and maternal morbidity have had mixed results. The impact of the duration between reaching maximum intrapartum temperature and delivery on neonatal outcomes remains unknown.

OBJECTIVE

To test the association of severity of intrapartum fever and duration from reaching maximum temperature to delivery with neonatal and maternal morbidity.

STUDY DESIGN

This was a secondary analysis of a prospective cohort of term, singleton patients admitted for induction of labor or spontaneous labor who had intrapartum fever (≥38°C). Patients were divided into 3 groups according to maximum temperature during labor: afebrile (<38°C), mild fever (38°C-39°C), and severe fever (>39°C). The primary outcome was composite neonatal morbidity (umbilical artery pH <7.1, mechanical ventilation, respiratory distress, meconium aspiration with pulmonary hypertension, hypoglycemia, neonatal intensive care unit admission, and Apgar <7 at 5 minutes). Secondary outcomes were composite neonatal neurologic morbidity (hypoxic-ischemic encephalopathy, hypothermia treatment, and seizures) and composite maternal morbidity (postpartum hemorrhage, endometritis, and maternal packed red blood cell transfusion). Outcomes were compared between the maximum temperature groups using multivariable logistic regression. Cox proportional-hazards regression modeling accounted for the duration between reaching maximum intrapartum temperature and delivery.

RESULTS

Of the 8132 patients included, 278 (3.4%) had a mild fever and 74 (0.9%) had a severe fever. The incidence of composite neonatal morbidity increased with intrapartum fever severity (afebrile 5.4% vs mild 18.0% vs severe 29.7%; P<.01). After adjusting for confounders, there were increased odds of composite neonatal morbidity with severe fever compared with mild fever (adjusted odds ratio, 1.93 [95% confidence interval, 1.07-3.48]). Severe fevers remained associated with composite neonatal morbidity compared with mild fevers after accounting for the duration between reaching maximum intrapartum temperature and delivery (adjusted hazard ratio, 2.05 [95% confidence interval, 1.23-3.43]). Composite neonatal neurologic morbidity and composite maternal morbidity were not different between patients with mild and patients with severe fevers.

CONCLUSION

Composite neonatal morbidity correlated with intrapartum fever severity in a potentially dose-dependent fashion. This correlation was independent of the duration from reaching maximum intrapartum temperature to delivery, suggesting that clinical management of intrapartum fever, in terms of timing or mode of delivery, should not be affected by this duration.

Placental growth factor level is correlated with intrapartum fetal heart rate findings

Objective

Here, we tested the correlation between maternal placental growth factor (PlGF) and fetal heart rate (FHR) monitoring findings.

Methods

We included 35 women with single pregnancies from 35 to 42 weeks of gestation who were hospitalized owing to onset of labor. Blood samples were collected at the start of labor. Intrapartum FHR monitoring parameters included total deceleration area, average deceleration area (mean deceleration area per 10 min), and five-tier classification level.

Results

Of the 35 women, 26 (74%) had vaginal delivery and 9 (26%) had cesarean section. After excluding 2 women who had cesarean section for arrest of labor, we analyzed 26 women who had vaginal delivery (VD group) and 7 who had cesarean section for fetal indications (CSF group). PlGF level was significantly higher in the VD group (157 ± 106 pg/ml) than in the CSF group (74 ± 62 pg/ml) (P = 0.03). There were no significant correlations between PlGF and total (r = -0.07) or average (r = -0.08) deceleration area.　There was a significant negative correlation (r = -0.42, P = 0.01) between PlGF and the percentage of level 3 or higher in the five-level classification.

Conclusion

PlGF was correlated with FHR monitoring findings and might be a promising biomarker of intrapartum fetal function.

Short-term morbidity and types of intrapartum hypoxia in the newborn with metabolic acidaemia: a retrospective cohort study

Objectives

To assess labour characteristics in relation to the occurrence of Composite Adverse neonatal Outcome (CAO) within a cohort of fetuses with metabolic acidaemia.

Design

Retrospective cohort study.

Setting

Three Italian tertiary maternity units.

Population

431 neonates born with acidaemia ≥36 weeks.

Methods

Intrapartum CTG traces were assigned to one of these four types of labour hypoxia: acute, subacute, gradually evolving and chronic hypoxia. The presence of CAO was defined by the occurrence of at least one of the following: Sarnat Score grade ≥2, seizures, hypothermia and death <7 days from birth.

Main outcome measures

To compare the type of hypoxia on the intrapartum CTG traces among the acidaemic neonates with and without CAO.

Results

The occurrence of a CAO was recorded in 15.1% of neonates. At logistic regression analysis, the duration of the hypoxia was the only parameter associated with CAO in the case of an acute or subacute pattern (odds ratio [OR] 1.3; 95% CI 1.02–1.6 and OR 1.04; 95% CI 1.0–1.1, respectively), whereas both the duration of the hypoxic insult and the time from PROM to delivery were associated with CAO in those with a gradually evolving pattern (OR 1.13; 95% CI 1.01–1.3 and OR 1.04; 95% CI 1.0–1.7, respectively). The incidence of CAO was higher in fetuses with chronic antepartum hypoxia than in those showing CTG features of intrapartum hypoxia (64.7 vs. 13.0%; P < 0.001).

Conclusions

The frequency of CAO seems related to the duration and the type of the hypoxic injury, being higher in fetuses showing CTG features of antepartum chronic hypoxia.

Tweetable abstract

This study demonstrates that in a large population of neonates with metabolic acidaemia at birth, the overall incidence of short‐term adverse outcome is around 15%. Such risk seems closely correlated to the duration and the type of hypoxic injury, being higher in fetuses admitted in labour with antepartum chronic hypoxia than those experiencing intrapartum hypoxia.

This study demonstrates that in a large population of neonates with metabolic acidaemia at birth, the overall incidence of short‐term adverse outcome is around 15%. Such risk seems closely correlated to the duration and the type of hypoxic injury, being higher in fetuses admitted in labour with antepartum chronic hypoxia than those experiencing intrapartum hypoxia.

Application of a Proposed Algorithm to Cesarean Deliveries for Nonreassuring Fetal Heart Rate Tracing

OBJECTIVES

The aim of the study is to evaluate how current management of Category II fetal heart rate tracings compares with that suggested by a published algorithm and whether these differences lead to disparate neonatal outcomes.

STUDY DESIGN

This is a retrospective observational study from the resident service at an academic-community tertiary care center from 2013 to 2018. We reviewed archived fetal heart rate tracings from patients with cesarean delivery performed for nonreassuring fetal heart rate tracing and interpreted tracings against the algorithm. We assigned tracings to one of three categories: Group A-consistent; Group B-inconsistent too early (algorithm permits the patient to labor longer); Group C-inconsistent too late (algorithm suggests performing the cesarean delivery sooner). Maternal demographics, features of labor, and neonatal outcomes were compared.

RESULTS

Of the 110 cases, 27 (24.5%) had a cesarean delivery performed in group A, 49 (44.5%) in group B, and 34 (30.9%) in group C. Baseline characteristics were similar. Of the 49 in group B, 46 (93.9%) violated the algorithm at the same branchpoint. In group C, cesarean deliveries would have been performed on average 244 minutes earlier had the algorithm been used. Neonatal outcomes were not significantly different among the groups, including 5-minute Apgar <7, pH <7.1, and NICU admit.

CONCLUSION

Our retrospective application of the algorithm showed that 44.5% of patients who have cesarean delivery for nonreassuring fetal heart rate tracing may be able to labor longer and that violation at a common decision point on the algorithm (moderate variability or accelerations, but a lack of recurrent decelerations) is responsible for nearly all such cesarean deliveries. More studies are needed to evaluate if cesarean delivery rates for nonreassuring fetal heart rate tracing can be reduced without impacting neonatal outcomes using the algorithm.

KEY POINTS

· There is a potential to further standardize management of Category II fetal heart rate tracings.. · In our practice, 25% of cesareans performed for fetal distress were consistent with the algorithm.. · A subset of patients (45%) with cesarean for fetal distress may have been able to labor longer..

Machine Learning Algorithm to Predict Acidemia Using Electronic Fetal Monitoring Recording Parameters

Background: Electronic fetal monitoring (EFM) is the universal method for the surveillance of fetal well-being in intrapartum. Our objective was to predict acidemia from fetal heart signal features using machine learning algorithms. Methods: A case–control 1:2 study was carried out compromising 378 infants, born in the Miguel Servet University Hospital, Spain. Neonatal acidemia was defined as pH < 7.10. Using EFM recording logistic regression, random forest and neural networks models were built to predict acidemia. Validation of models was performed by means of discrimination, calibration, and clinical utility. Results: Best performance was attained using a random forest model built with 100 trees. The discrimination ability was good, with an area under the Receiver Operating Characteristic curve (AUC) of 0.865. The calibration showed a slight overestimation of acidemia occurrence for probabilities above 0.4. The clinical utility showed that for 33% cutoff point, missing 5% of acidotic cases, 46% of unnecessary cesarean sections could be prevented. Logistic regression and neural networks showed similar discrimination ability but with worse calibration and clinical utility. Conclusions: The combination of the variables extracted from EFM recording provided a predictive model of acidemia that showed good accuracy and provides a practical tool to prevent unnecessary cesarean sections.

Physiological control of fetal heart rate variability during labour: Implications and controversies

The interpretation of fetal heart rate (FHR) patterns is the only available method to continuously monitor fetal wellbeing during labour. One of the most important yet contentious aspects of the FHR pattern is changes in FHR variability (FHRV). Some clinical studies suggest that loss of FHRV during labour is a sign of fetal compromise so this is reflected in practice guidelines. Surprisingly, there is little systematic evidence to support this observation. In this review we methodically dissect the potential pathways controlling FHRV during labour-like hypoxaemia. Before labour, FHRV is controlled by the combined activity of the parasympathetic and sympathetic nervous systems, in part regulated by a complex interplay between fetal sleep state and behaviour. By contrast, preclinical studies using multiple autonomic blockades have now shown that sympathetic neural control of FHRV was potently suppressed between periods of labour-like hypoxaemia, and thus, that the parasympathetic system is the sole neural regulator of FHRV once FHR decelerations are present during labour. We further discuss the pattern of changes in FHRV during progressive fetal compromise and highlight potential biochemical, behavioural and clinical factors that may regulate parasympathetic-mediated FHRV during labour. Further studies are needed to investigate the regulators of parasympathetic activity to better understand the dynamic changes in FHRV and their true utility during labour. This article is protected by copyright. All rights reserved.

Variable deceleration features and intrapartum fetal acidemia - The role of deceleration area

OBJECTIVE

In recent years deceleration area has received increasing attention as a potential predictor of intrapartum fetal hypoxia. In several studies, the area has been manually esteemed as triangular in shape, which might introduce bias. In addition, the commonly used outcome acidemia in umbilical artery is affected by mode of delivery. We wanted to investigate the association between the variable deceleration features area, duration, depth and cumulative deceleration area (30 and 60 min) and intrapartum fetal acidemia measured as lactate concentration at fetal scalp blood sampling (FBS) in immediate connection to the decelerations.

STUDY DESIGN

In the source population of 1070 labors at Karolinska University Hospital, Sweden, with FBS performed on indication, we found 507 fetuses with predominantly variable decelerations as the indication for FBS. We examined the last 60- and 30-minutes of fetal monitoring preceding the FBS with focus on deceleration area, duration and depth. The contours of the decelerations were outlined manually but the area was calculated with a computer software program. We assessed area, duration and depth both as mean values per deceleration and as cumulative values during the time period of interest. We analyzed Pearson correlations and area under receiver operating characteristics curves (AUC). We also performed an adjusted analysis, with baseline frequency, variability, and accelerations as covariates.

RESULTS

Deceleration area and duration were the best predictors of intrapartum fetal acidemia (fetal lactate concentration >4.8 mmol/L measured with Lactate Pro™) with AUCs of 0.671 (0.682) and 0.678 (0.683) for cumulative measures during 30 (60) minutes prior to FBS, compared to deceleration depth with AUC of 0.632 (0.631). Corresponding Pearson correlations in 30-min (60-min) groups were 0.329 (0.335) and 0.358 (0.354) for deceleration area and duration and 0.212 (0.204) for deceleration depth. Using 250 beats cumulative cut-off for deceleration area during last 30 min, 71% vs. 43% were acidemic and non-acidemic, odds ratio = 3.2 (95% CI 1.7-6.1).

CONCLUSIONS

Deceleration area and duration were better predictors of intrapartum fetal acidemia than deceleration depth. Cumulative deceleration area >250 beats during 30 min was associated with three-fold higher odds of intrapartum acidemia compared to <250 beats.

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

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

The present and future of intrapartum computerized cardiotocography: role of pattern recognition incorporating single vs. multiple parameters

Computer assisted cardiotocography holds a great promise in minimizing human errors thereby improving perinatal outcome. Despite exponential growth (Moore's law) in computing power for decades, this promise remains unrealized. The systematic analyses of studies on computerized cardiotocography offer little guide to future. This analytical review presents a more qualitative discussion of available evidence as well as concepts regarding the development and acceptance of computerized cardiotocography. To begin with, a workable approach would be for computer algorithms to follow the most scientific visual cardiotocography interpretation frameworks incorporating multiple fetal heart rate parameters and uterine contractions. This ability could be studied and form the basis for regulation of computer algorithms. Addition of background risk factors would be another step. This may take form of familiar multi-tier systems or new alternative strategies like the fetal reserve index. "Machine learning" will remain challenging because of complex variability in fetal-maternal conditions, labor characteristics and clinical intervention changing the outcomes. Randomized controlled trials of adequate size may remain very rare. However, prospective and retrospective testing of computer algorithms with careful qualitative and comparative approach would help clinicians and hospital managers in their decisions. Singular parameters like the popular "deceleration area" and "deceleration capacity" have poor predictive value for fetal acidemia or hypoxic injury. Scientific pattern-recognition of important fetal heart rate parameters like decelerations seems crucial for visual as well as computerized cardiotocography. Success of computerizedcardiotocography depends on team effort by the obstetricians with in-depth practical knowledge/experience and skilled artificial intelligence (AI) specialists.

Relationship Between Umbilical Cord Gas Values and Neonatal Outcomes: Implications for Electronic Fetal Heart Rate Monitoring

OBJECTIVE

To evaluate the relationship between umbilical artery cord gas values and fetal tolerance of labor, as reflected by Apgar score. We hypothesized the existence of wide biological variability in fetal tolerance of metabolic acidemia, which, if present, would weaken one fundamental assumption underlying the use of electronic fetal heart rate (FHR) monitoring.

METHODS

We conducted a retrospective cohort study of term, singleton, nonanomalous fetuses delivered in our institution between March 2012 and July 2020. Universally obtained umbilical cord gas values and Apgar scores were extracted. We calculated Spearman correlation coefficients and receiver operating characteristic curves for various levels of umbilical artery pH, base excess, and Apgar scores.

RESULTS

We analyzed data from 29,787 deliveries. The statistical correlation between umbilical artery pH and base excess and both 1- and 5-minute Apgar scores was weak or nonexistent in all pH range subgroups (range 0.064-0.213). Receiver operating characteristic curve analysis suggested umbilical artery pH value of 7.22 yields the best discrimination for prediction of a severely depressed newborn (5-minute Apgar score less than 4), but sensitivity and specificity for this predictive value remains poor to moderate.

CONCLUSION

The use of electronic FHR monitoring is predicated on a documented relationship between FHR patterns and umbilical artery pH, and an assumed correlation between pH and fetal outcomes, reflecting fetal tolerance of labor and delivery. Our data demonstrate a weak-to-absent correlation between metabolic acidemia and even short-term fetal condition, thus significantly weakening this latter assumption. No amount of future modification of FHR pattern interpretation to better predict newborn pH is likely to lead to improved newborn outcomes, given this weakness in a fundamental assumption on which FHR monitoring is based.

Unusual Circumstances and Additional Procedures for Fetal Evaluation in Labor

This chapter describes several circumstances in which the interpretation of the intrapartum fetal heart rate pattern falls outside the usual frame of reference. This includes a more extensive discussion of causes of tachycardia and bradycardia. Ways in which a fetal dysrhythmia may manifest itself in the context of heart rate monitoring are described. Finally, the chapter reviews technological innovations designed to clarify the fetal status when compromise is suspected from the fetal heart rate pattern.

Interpretation of Fetal Heart Rate Monitoring in the Clinical Context

Use of intrapartum fetal heart rate (FHR) monitoring has had limited success in preventing hypoxic injury to neonates. One of the most common limitations of FHR interpretation is the failure to consider chronic and acute clinical factors that may increase the risk of evolving acidemia. This manuscript reviews common clinical factors that may affect the FHR and should be considered when determining the need for early intervention based on changes in the FHR.

No. 396-Fetal Health Surveillance: Intrapartum Consensus Guideline

OBJECTIVE

To present evidence and recommendations regarding use, classification, interpretation, response, and documentation of fetal surveillance in the intrapartum period and to provide information to help minimize the risk of birth asphyxia while maintaining the lowest possible rate of obstetrical intervention.

INTENDED USERS

Members of intrapartum care teams, including but not limited to obstetricians, family physicians, midwives and nurses, and their learners TARGET POPULATION: Intrapartum women OPTIONS: All methods of uterine activity assessment and fetal heart rate surveillance were considered in developing this document.

OUTCOMES

The impact, benefits, and risks of different methods of surveillance on the diverse maternal-fetal health conditions have been reviewed based on current evidence and expert opinion. No fetal surveillance method will provide 100% detection of fetal compromise; thus, all FHS methods are viewed as screening tests. As the evidence continues to evolve, caregivers from all disciplines are encouraged to attend evidence-based Canadian educational programs every 2 years.

EVIDENCE

Literature published between January 1976 and February 2019 was reviewed. Medline, the Cochrane Database, and international guidelines were used to search the literature for all studies on intrapartum fetal surveillance.

VALIDATION METHODS

The principal and contributing authors agreed to the content and recommendations. The Board of the Society of Obstetricians and Gynaecologists of Canada approved the final draft for publication. The level of evidence has been determined using the criteria and classifications of the Canadian Task Force on Preventive Health Care.

BENEFITS, HARM, AND COSTS

Consistent interdisciplinary use of the guideline, appropriate equipment, and trained professional staff enhances safe intrapartum care. Women and their support person(s) should be informed of the benefits and harms of different methods of fetal health surveillance.

RECOMMENDATIONS

CommunicationSupport During Active LabourPrinciples of Intrapartum Fetal SurveillanceSelecting the Method of Fetal Heart Rate Monitoring: Intermittent Auscultation or Electronic Fetal MonitoringPaper SpeedAdmission AssessmentsEpidural AnalgesiaIntermittent Auscultation in LabourElectronic Fetal Monitoring in LabourClassification of Intrapartum Fetal SurveillanceMaternal Heart RateFetal Health Surveillance Assessment in the Active Second Stage of LabourIntrauterine ResuscitationDigital Fetal Scalp StimulationFetal Scalp Blood SamplingUmbilical Cord Blood GasesDocumentationFetal Surveillance Technology Not RecommendedFetal Health Surveillance Education.

Deep neural network-based classification of cardiotocograms outperformed conventional algorithms

Cardiotocography records fetal heart rates and their temporal relationship to uterine contractions. To identify high risk fetuses, obstetricians inspect cardiotocograms (CTGs) by eye. Therefore, CTG traces are often interpreted differently among obstetricians, resulting in inappropriate interventions. However, few studies have focused on quantitative and nonbiased algorithms for CTG evaluation. In this study, we propose a newly constructed deep neural network model (CTG-net) to detect compromised fetal status. CTG-net consists of three convolutional layers that extract temporal patterns and interrelationships between fetal heart rate and uterine contraction signals. We aimed to classify the abnormal group (umbilical artery pH < 7.20 or Apgar score at 1 min < 7) and the normal group from CTG data. We evaluated the performance of the CTG-net with the F1 score and compared it with conventional algorithms, namely, support vector machine and k-means clustering, and another deep neural network model, long short-term memory. CTG-net showed the area under the receiver operating characteristic curve of 0.73 ± 0.04, which was significantly higher than that of long short-term memory. CTG-net, a quantitative and automated diagnostic aid system, enables early intervention for putatively abnormal fetuses, resulting in a reduction in the number of cases of hypoxic injury.

Total intrapartum fetal reperfusion time (fetal resilience) and neonatal acidemia

OBJECTIVE

The main objective is to study the predictive capacity of intrapartum total fetal reperfusion (fetal resilience) by itself or in combination with other parameters as a predictor of neonatal acidemia.

STUDY DESIGN

A retrospective case-control study was carried out at the Miguel Servet University Hospital (Zaragoza, Spain) on a cohort of 5694 pregnant women between June 2017 and October 2018. Maternal, perinatal, and cardiotocographic records were collected. Two reviewers blindly described the monitors with the American College of Obstetricians and Gynecologists (ACOG) categorizations and parameters and the non-ACOG parameters. Neonatal acidemia was defined as pH <7.10. The parameters analyzed to predict acidemia were evaluated using the sensitivity for specificity 90% value, and the area under the receiver operating characteristic curve.

RESULTS

We recorded 192 infants with acidemia, corresponding to a global acidemia rate of 3.4%. Of these, 72 were excluded for lack of criteria, leaving 120 patients with arterial acidemia included in the study and 258 in the control group. The sensitivity (specificity 90%) of detection of acidemia was 42% for the ACOG III categorization (AUC, 0.524: 95% CI, 0.470-0.578), 24% for fetal reperfusion (AUC, 0.704: 95% CI, 0.649-0.759), 27% for total area of decelerations (AUC, 0.717: 95% CI, 0.664-0.771) and 50% for the multivariate model built from total reperfusion time (AUC, 0.826: 95% CI, 0.783-0.869). The total reperfusion time corresponding to a false negative rate of 10% is 23.75 min, with 28% of fetuses above this time. The AUC and sensitivity for a false negative rate of 10% are equivalent for deceleration area and time of reperfusion (p = .504).

CONCLUSION

The total reperfusion time (fetal resilience) and total deceleration area are non-ACOG parameters with a good predictive ability for neonatal acidemia, higher than the ACOG III classification and without statistical differences between them. The discrimination ability of total reperfusion time can be improved using a multivariate model. As a cutoff for its use we suggest 23.75 min in 30 min corresponding to an acidemic classification rate of 90%. New parameters in combination with other maternal, obstetrics, or fetal variables, are required for the interpretation of fetal well-being.

Transient effects of forebrain ischemia on fetal heart rate variability in fetal sheep

Fetal heart rate variability (FHRV) is a key index of antenatal and intrapartum fetal well-being. FHRV is well established to be mediated by both arms of the autonomic nervous system, but it remains unknown whether higher centers in the forebrain contribute to FHRV. We tested the hypothesis that selective forebrain ischemia would impair the generation of FHRV. Sixteen chronically instrumented near-term fetal sheep were subjected to either forebrain ischemia induced by bilateral carotid occlusion or sham-ischemia for 30 min. Time, frequency, and nonlinear measures of FHRV were assessed during and for seven days after ischemia. Ischemia was associated with profound suppression of electroencephalographic (EEG) power, which remained suppressed throughout the recovery period (P < 0.001). During the first 5 min of ischemia, multiple time and frequency domain measures were increased (all P < 0.05) before returning back to sham levels. A delayed increase in sample entropy was observed during ischemia (P < 0.05). For the first 3 h after ischemia, there was moderate suppression of two measures of FHRV (very-low frequency power and the standard deviation of RR-intervals, both P < 0.05) and increased sample entropy (P < 0.05). Thereafter, all measures of FHRV returned to control levels. In conclusion, profound forebrain ischemia sufficient to lead to severe neural injury had only transient effect on multiple measures of FHRV. These findings suggest that the forebrain makes a limited contribution to FHRV. FHRV therefore primarily originates in the hindbrain and is unlikely to provide meaningful information on forebrain neurodevelopment or metabolism.

Fetal Heart Rate Decelerations in Women with Sleep-Disordered Breathing

Emerging literature has shown that women with sleep-disordered breathing (SDB) have increased risk for gestational hypertension/preeclampsia and gestational diabetes. Case reports suggest an association between maternal apnea and fetal heart rate deceleration but data are lacking on how maternal sleep impacts fetal health. Since decelerations may be associated with adverse outcomes, we sought to determine whether fetal heart rate decelerations were associated with SDB. A cohort study of third trimester pregnant women with a singleton fetus was conducted. Participants underwent a home sleep test with continuous portable electronic fetal monitoring. SDB was defined as a respiratory disturbance index (RDI)≥10 events/hour. The temporality between a respiratory event and fetal heart rate decelerations was determined to be present if a deceleration occurred < 30 s after a respiratory event. Forty women were included with mean (±SD) age, BMI, and gestational age of 32.0±5.5 years, 37.1±8.0 kg/m², and 34.6±2.4 weeks respectively. Overall, n=23 (57.5%) women had SDB. Thirty-seven late decelerations were observed in 18 women; of these, 84% were temporally associated with a respiratory event. Nine of the 18 women (50%) had SDB. Ten prolonged decelerations were observed in 6 women of which nine (90%) were temporally associated with a respiratory event. Five of the six women (83%) had an RDI≥10. These initial data suggest that, in this population, the majority of both late and prolonged fetal heart rate decelerations occur with a maternal respiratory event. Since respiratory events are characteristic of maternal SDB, this raises the possibility that SDB may influence fetal well-being.

Prediction of severe adverse neonatal outcomes at the second stage of labour using machine learning: a retrospective cohort study

OBJECTIVE

To create a personalised machine learning model for prediction of severe adverse neonatal outcomes (SANO) during the second stage of labour.

DESIGN

Retrospective Electronic-Medical-Record (EMR) -based study.

POPULATION

A cohort of 73 868 singleton, term deliveries that reached the second stage of labour, including 1346 (1.8%) deliveries with SANO.

METHODS

A gradient boosting model was created, analysing 21 million data points from antepartum features (e.g. gravidity and parity) gathered at admission to the delivery unit, and intrapartum data (e.g. cervical dilatation and effacement) gathered during the first stage of labour. Deliveries were allocated to high-risk and low-risk groups based on the Youden index to maximise sensitivity and specificity.

MAIN OUTCOME MEASURES

SANO was defined as either umbilical cord pH levels ≤7.1 or 1-minute or 5-minute Apgar score ≤7.

RESULTS

The model for prediction of SANO yielded an area under the receiver operating curve (AUC) of 0.761 (95% CI 0.748-0.774). A third of the cohort (33.5%, n = 24 721) were allocated to a high-risk group for SANO, which captured up to 72.1% of these cases (odds ratio 5.3, 95% CI 4.7-6.0; high-risk versus low-risk groups).

CONCLUSIONS

Data acquired throughout the first stage of labour can be used to predict SANO during the second stage of labour using a machine learning model. Stratifying parturients at the beginning of the second stage of labour in a 'time out' session, can direct a personalised approach to management of this challenging aspect of labour, as well as improve allocation of staff and resources.

TWEETABLE ABSTRACT

Personalised prediction score for severe adverse neonatal outcomes in labour using machine learning model.

Fetal Heart Rate Tracing Category II: A Broad Category in Need of Stratification

Fetal heart rate (FHR) tracings are classified into 3 categories per the National Institute of Child Health and Human Development guidelines. There exists broad consensus on the recognition and management of categories I and III. However, a category II FHR tracing is considered "indeterminate" and cannot be classified as either reassuring or non-reassuring. Absence of variability and high frequency and increased depth of decelerations are the key determining factors that make a category II tracing non-reassuring and are associated with fetal metabolic acidosis. Periodic category II tracing is present in the majority of normal laboring patients. In the setting of a category II tracing, an initial attempt should be made for in utero resuscitation of the fetus. If the tracing fails to improve over a period of 1 to 2 hours, or the fetal tracing gradually deteriorates, a decision should be made for operative vaginal or cesarean delivery. Category II tracing management algorithms can aid in decision-making in this uncertain clinical scenario. Team training and simulation may improve team performance and have a positive impact on neonatal outcomes.