Intrapartum deceleration and acceleration areas are associated with neonatal encephalopathy

Ultrasound evaluation of the size of the umbilical cord vessels and Wharton's jelly and correlation with intrapartum CTG findings

OBJECTIVE

To compare the sonographic measurement of the umbilical cord between women with or without repetitive decelerations during the first stage of labor.

STUDY DESIGN

Prospective study including a non-consecutive cohort of women at term gestation carrying a normal sized fetus at term in cephalic presentation. The cross-sectional area of the umbilical cord, of its vessels and the amount of the Wharton's jelly were assessed at 2D ultrasound upon labor admission. The CTG traces recorded in labor were retrospectively evaluated and the biometric parameters of the umbilical cord were compared between women with or without repetitive decelerations during the first stage and their correlation with the total deceleration area/total length (stage I TDA/t) of the first stage of labor (overall and following the rupture of membrane) was assessed.

RESULTS

Overall, 113 women were included, of whom 21 (18.6 %) presented repetitive decelerations during the first stage of labor. In this latter group, the umbilical cord showed a significantly smaller total arterial area (24.4 ± 10.7 vs. 19.6 ± 9.0 mm2; p = 0.02), vein area (46.8 ± 13.6 vs. 34.1 ± 13.3 mm2; p < 0.001) as well Wharton's Jelly (WJ) area (122.7 ± 32.1 vs. 79.3 ± 11.1 mm2; p < 0.001) compared with fetuses with a normal CTG. At logistic regression analysis the WJ area was associated with the occurrence of repetitive decelerations during the first stage of labor (p < 0.001). The I stage TDA/t overall and after the rupture of membranes was found to be negatively correlated with the WJA (Spearman's coefficient -0.40; p < 0.001 and -0.45; p < 0.001 respectively).

CONCLUSION

In normal sized infants a reduced umbilical cord thickness is associated with an increased occurrence of repetitive decelerations during the first stage of labor. The severity of these decelerations is negatively correlated to the amount of WJ.

The peripheral chemoreflex and fetal defenses against intrapartum hypoxic-ischemic brain injury at term gestation

Fetal hypoxemia is ubiquitous during labor and, when severe, is associated with perinatal death and long-term neurodevelopmental disability. Adverse outcomes are highly associated with barriers to care, such that developing countries have a disproportionate burden of perinatal injury. The prevalence of hypoxemia and its link to injury can be obscure, simply because the healthy fetus has robust coordinated defense mechanisms, spearheaded by the peripheral chemoreflex, such that hypoxemia only becomes apparent in the minority of cases associated with stillbirth, severe metabolic acidemia or adverse neurodevelopmental outcomes. This represents only the extreme end of the spectrum, when defense mechanisms have failed due to severe/prolonged hypoxemia, or the fetal defenses are compromised by additional risk factors. Understanding the fetal defenses to hypoxemia and when the fetus begins to decompensate is crucial to understanding perinatal health and disease, by linking antenatal health, intrapartum events, the neonatal trajectory and ultimately life-long neurodevelopmental health.

A systematic catalog of studies on fetal heart rate pattern and neonatal outcome variables

OBJECTIVES

To study the methodology and results of studies assessing the relationship between fetal heart rate and specified neonatal outcomes including, heart rate, infection, necrotizing enterocolitis, intraventricular hemorrhage, hypoxic-ischemic encephalopathy, and seizure.

METHODS

Embase, Medline ALL, Web of Science Core Collection, Cochrane Central Register of Controlled Trials, and CINAHL were searched from inception to October 5, 2023.

RESULTS

Forty-two studies were included, encompassing 57,232 cases that underwent fetal monitoring and were evaluated for neonatal outcome. Heterogeneity was observed in the timing and duration of fetal heart rate assessment, classification guidelines used, number of assessors, and definition and timing of neonatal outcome assessment. Nonreassuring fetal heart rate was linked to lower neonatal heart rate variability. A significant increase in abnormal fetal heart rate patterns were reported in neonates with hypoxic-ischemic encephalopathy, but the predictive ability was found to be limited. Conflicting results were reported regarding sepsis, seizure and intraventricular hemorrhage. No association was found between necrotizing enterocolitis rate and fetal heart rate.

CONCLUSIONS

There is great heterogeneity in the methodology used in studies evaluating the association between fetal heart rate and aforementioned neonatal outcomes. Hypoxic-ischemic encephalopathy was associated with increased abnormal fetal heart rate patterns, although the predictive ability was low. Further research on developing and evaluating an automated early warning system that integrates computerized cardiotocography with a perinatal health parameter database to provide objective alerts for patients at-risk is recommended.

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 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.

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.