Electronic fetal heart rate monitoring: early neonatal outcomes associated with normal rate, fetal stress, and fetal distress

Correlation between the 5-tier fetal heart rate pattern classification at delivery and Apgar scores

AIM

In Japan, the fetal heart rate pattern on cardiotocography is usually categorized into five levels for intrapartum management; however, studies on the 5-tier cardiotocography classification are limited. This study aimed to determine the correlation between 5-tier cardiotocography levels at delivery, neonatal Apgar scores and perinatal prognosis using a perinatal registry database.

METHODS

This retrospective study used the 2018 Perinatal Registry Database of the Japan Society of Obstetrics and Gynecology. Apgar scores and perinatal prognosis were compared between patients with Japan Society of Obstetrics and Gynecology intrapartum cardiotocography levels 1-2, and levels 3-5.

RESULTS

In total, 240 987 cases were registered, with 114 201 full-term deliveries comprising 84 703 vaginal and 29 498 cesarean deliveries. For vaginal delivery cases, the crude odds ratios of 1-min Apgar score ≤3 for levels 3 (odds ratio: 1.7, 95% confidence interval: 1.4-2.0, p < 0.0001), levels 4 (odds ratio: 5.9, 95% confidence interval: 5.1-6.9, p < 0.0001), and levels 5 (odds ratio: 49.2, 95% confidence interval: 37.5-64.5, p < 0.0001) were significantly higher than those for levels 1-2 (odds ratio: 1.0). Moreover, the crude odds ratios of 5-min Apgar score ≤ 3 for levels 4 (odds ratio: 4.8, confidence interval: 2.7-8.7, p < 0.0001), and levels 5 (odds ratio: 71.1, confidence interval: 32.6-155.1, p < 0.0001) were significantly higher than those for levels 1-2 (odds ratio: 1.0). Similarly, in cases of cesarean delivery, it showed a similar trend to case of vaginal delivery cases.

CONCLUSION

The 5-tier cardiotocography classification can predict severe neonatal asphyxia.

Telemedicine for home care of fetal growth restriction with mobile cardiotocography: A case series

OBJECTIVE

Modern technological advancements have made it possible to perform cardiotocography at home. Home-based management of high-risk pregnancies using a mobile cardiotocography system has been reported; however, its effectiveness in monitoring cases of fetal growth restriction (FGR) remains unclear. Therefore, the authors aimed to investigate the clinical usefulness of home-based telemedicine for FGR management using the mobile cardiotocography (iCTG).

METHODS

The authors conducted a single-center, retrospective case series of patients with FGR. Seventeen women diagnosed with FGR were enrolled. Patients performed iCTG for 1 hour twice daily to examine their fetuses; data were uploaded and saved on the cloud.

RESULTS

The median and minimum compliance rates were 93.33 (interquartile range [IQR], 70.00-100.00 and 40.7, respectively). The median and minimum validity rates were 100.00 (IQR, 90.48-100.00) and 36.4, respectively. In this study, many of the patients were managed at home and underwent delivery as planned. However, three patients required emergency visits; one had a nonreassuring fetal status and underwent an emergency cesarean section.

CONCLUSION

Even when the fetal prognosis is good, careful pre-evaluation is required before initiating home care management. The current study shows that the economic burden of hospitalization for patients can be reduced by using iCTG.

What Is the Role of the Maternal Ophthalmic and Cervical Internal Carotid Arteries in Predicting Maternal Adverse Outcomes in Preeclampsia?

OBJECTIVES

We aimed to investigate the efficacy of maternal ophthalmic artery (OA) and cervical internal carotid artery (CICA) in predicting adverse maternal outcomes and gestational age at birth in preeclampsia (PE).

METHODS

The study was performed at the Zeynep Kamil Women and Children's Diseases Training and Research Hospital. Measurements were made in 2 groups consisting of 50 pregnant women with PE and 50 healthy pregnant women. The peak systolic velocity (PSV), end-diastolic velocity, PI, RI, first diastolic peak velocity, systolic/diastolic (S/D) ratio, and peak ratio of the maternal OA were measured by a transorbital Doppler ultrasound (US) scan. The PSV, end-diastolic velocity, PI, RI, and S/D ratio of the CICA were measured. The differences of Doppler indices between groups with P < .05 were considered statistically significant. Cutoff values were calculated, which could be used to predict adverse maternal outcomes and gestational age at birth.

RESULTS

The RI and PI values of the OA were lower, and the first diastolic peak velocity, PSV, and peak ratio values were higher among the PE group. The RI and S/D values of the CICA were significantly lower in the PE group compared to the healthy group. The OA RI was determined to be the strongest US variable in predicting adverse maternal outcomes and gestational age at birth, with a cutoff value of 0.72, 76% sensitivity, and 76% specificity.

CONCLUSIONS

Maternal OA Doppler indices can be used as US markers to predict adverse maternal outcomes.

Evaluation of 3-tier and 5-tier FHR pattern classifications using umbilical blood pH and base excess at delivery

OBJECTIVE

The relevance between time-series fetal heart rate (FHR) pattern changes during labor and outcomes such as arterial blood gas data at delivery has not been studied. Using 3-tier and 5-tier classification systems, we studied the relationship between time-series FHR pattern changes before delivery and umbilical artery blood gas data at delivery.

METHODS

The subjects were 1,909 low-risk women with vaginal delivery (age: 29.1 ± 4.4 years, parity: 1.7 ± 0.8). FHR patterns were classified by a skilled obstetrician based on each 10 min-segment of the last 60 min before delivery from continuous CTG records in an obstetric clinic.

RESULTS

The relationship between each 10 min-segment FHR pattern classification from 60 minutes before delivery and umbilical artery blood pH and base excess (BE) values at delivery changed with time. In the 3-tier classification, mean pH of Category I group in each 10 min-segment was significantly higher than that of Category II group. For Category I groups in each 10-minute segment, its number decreased and its average pH increased as the delivery time approached. In the 5-tier classification, there was the same tendency. About each level group in 10 min-segment, the higher the level, the lower the blood gas values, and mean pH of higher level groups decreased as the delivery time approached.

CONCLUSIONS

The relationship between classifications and outcomes was clear at any time from 60 min before delivery in 3- and 5-tier classifications, and the 5-tier classification was more relevant.

Physiological CTG interpretation: the significance of baseline fetal heart rate changes after the onset of decelerations and associated perinatal outcomes

OBJECTIVE

To determine the perinatal outcomes in fetuses with baseline fetal heart rate changes with preceding decelerations on the cardiotocography (CTG) trace, and to interpret CTG traces from the aspect of fetal physiology.

MATERIALS AND METHODS

A retrospective analysis of 500 consecutive CTG traces was carried out. The presence of repetitive variable and late decelerations followed by the changes in the baseline including baseline tachycardia and abnormal baseline variability were determined. Perinatal outcomes including Apgar scores and umbilical arterial pH at birth, NNU admission, and meconium-stained amniotic fluid were analyzed. We interpreted the changes in CTG based on fetal physiology.

RESULTS

When repetitive variable and late decelerations were present without tachycardia (n = 81), none of the fetuses had an Apgar score <7 at 5 minutes or an umbilical cord pH <7. After the onset of fetal tachycardia (n = 262), fetuses showed decreased Apgar scores and umbilical arterial pH(p < .01), however, there was no significant difference in the rate of abnormal 5 min Apgar score, abnormal PH and NNU admission, if the baseline variability remained normal. However, if the baseline variability was abnormal (n = 44), (either increased or reduced) after tachycardia, there was a statistically significant increase in poor perinatal outcomes. Fetuses with abnormal versus normal variability had lower Apgar scores ≤7 at 5 min (29.6 versus 0.9%, p = .000); umbilical cord arterial pH <7 at birth (29.5 versus 0%, p = .000); increased admission to the NNU (27.3 versus 3.7%, p = .000) and increased incidence of meconium-stained amniotic fluid (38.6 versus 22.5%, p = .024). These serial changes in CTG could be interpreted and predicted by the application of fetal physiology.

CONCLUSIONS

There were significant differences in perinatal outcomes when fetuses were exposed to evolving intrapartum hypoxic stress culminating in an abnormal baseline fetal heart rate variability, which was preceded by repetitive decelerations, followed by an increase in the baseline heart rate. However, despite ongoing decelerations, if the baseline variability remained normal, none of the fetuses had a pH of <7. Therefore, the knowledge of fetal physiological response to evolving hypoxic stress can be reliably used to determine fetal compensation.

Multi-lag tone-entropy in neonatal stress

Heart rate variability (HRV) has been analysed using linear and nonlinear methods. In the framework of a controlled neonatal stress model, we applied tone-entropy (T-E) analysis at multiple lags to understand the influence of external stressors on healthy term neonates. Forty term neonates were included in the study. HRV was analysed using multi-lag T-E at two resting and two stress phases (heel stimulation and a heel stick blood drawing phase). Higher mean entropy values and lower mean tone values when stressed showed a reduction in randomness with increased sympathetic and reduced parasympathetic activity. A ROC analysis was used to estimate the diagnostic performances of tone and entropy and combining both features. Comparing the resting and simulation phase separately, the performance of tone outperformed entropy, but combining the two in a quadratic linear regression model, neonates in resting as compared to stress phases could be distinguished with high accuracy. This raises the possibility that when applied across short time segments, multi-lag T-E becomes an additional tool for more objective assessment of neonatal stress.

Asymmetric detrended fluctuation analysis in neonatal stress

OBJECTIVE

To detect stress in newborns by observing heart rate (HR) variability utilizing an asymmetric detrended fluctuation analysis (ADFA), we sought to determine the fractal structure of the series of inter-beat intervals, so as to distinguish the periods of acceleration of the HR from decelerations. Thus, two scaling exponents, α ⁺ and α ^-, representing decelerations and accelerations respectively, are obtained.

APPROACH

Forty healthy term newborns were included in this study, undergoing two different types of stress stimuli: routine heel lance blood sampling for metabolic screening purposes, and its simulation by applying dull pressure on the heel.

MAIN RESULTS

It appears that when newborns face stress, the scaling exponent related to accelerations significantly increases and becomes higher than the deceleration scaling exponent. To test the diagnostic properties of the scaling exponents, an ROC curve analysis was applied; α ^- showed good diagnostic performance with an AUC between 0.626 and 0.826, depending on the length of the time series. The joint use of α ⁺ and α ^- further increased the diagnostic performance, in particular for shorter series of RR intervals, with an AUC between 0.691 and 0.833.

SIGNIFICANCE

ADFA, particularly of the acceleration scaling exponent, may be a useful clinical diagnostic tool for monitoring neonatal stress.

The effect of the systematic birth preparation program on fear of vaginal delivery and quality of life

PURPOSE

The aim of this study was to assess the impact of systematic birth preparation program on fear of vaginal delivery and quality of life (QoL) in pregnant women who request elective cesarean delivery without any obstetric indication.

METHODS

This study was conducted prospectively. A total of 100 women who requested elective cesarean delivery due to psychosocial reasons were included into the study. Women were divided into two groups according to their desire to participate in the systematic birth preparation program. Group A: case group (n = 50) consisted of women who participated in the systematic birth preparation program. Group B: control group (n = 50) received usual antenatal care. All patients were interviewed with questionnaires including the World Health Organization Quality of Life Assessment-BREF (WHOQOL-BREF) and Edinburgh Postnatal Depression Scale (EPDS) at postpartum 6th week. Type of delivery, maternal request for cesarean section, scores for QoL, and postpartum depression were compared between the two groups.

RESULTS

Vaginal delivery rate was significantly higher in among the patients who received the systematic birth preparation program (group A: 78%, group B: 56%). Maternal request for elective cesarean section significantly decreased after the systematic birth preparation program (group A: 8%, group B: 28%). In group A, the WHOQOL-BREF-TR mean scores (SD) for physical domain, psychological domain, and environmental domain were significantly higher than the values exhibited in group B. In scores of the postpartum depression scale, there were no significant differences between the two groups (p = 0.075).

CONCLUSIONS

The current study indicates that systematic birth preparation program may decrease the rate of elective cesarean delivery by reducing fear of vaginal delivery and improve the quality of life at postpartum period.

Caesarean Section for Foetal Distress and Correlation with Perinatal Outcome

BACKGROUND

The main documented indication of intrapartum caesarean section is foetal distress (MacKenzie and Cooke in BMJ 323(7318):930, 2001). Foetal distress indicates foetal hypoxia and acidosis during intrauterine life.

PURPOSE

To correlate the diagnosis of foetal distress and perinatal outcome.

METHODS

This was a prospective observational study of women who underwent caesarean section for foetal distress as detected by cardiotocography and not responding to intrauterine resuscitation. The foetal Apgar score at 1 and 5 min was recorded and cord blood pH was measured in all cases. The neonatal outcome was studied with regard to the need for supportive ventilation and admission to NICU/nursery.

RESULTS

In our study, 14.38 % cases diagnosed with foetal distress subsequently had poor outcome. Twenty-one babies had a 5-min Apgar score <7, required immediate resuscitation and were admitted in NICU. Twelve foetuses had a 1-min Apgar score <4, while there were three cases of severe birth asphyxia (Apgar score <4 at 5 min); of these, two babies died. The neonatal outcome was poorer in cases with associated complicating factors.

CONCLUSION

The diagnosis of foetal distress is imprecise and a poor predictor of foetal outcome-the result is a tendency for unnecessary caesarean sections. On the contrary, lack of adverse outcome could reflect that our unit makes decisions at a time before clinically significant foetal compromise occurs.

Fetal movements as a predictor of health

The key determinant to a fetus maintaining its health is through adequate perfusion and oxygen transfer mediated by the functioning placenta. When this equilibrium is distorted, a number of physiological changes, including reduced fetal growth, occur to favor survival. Technologies have been developed to monitor these changes with a view to prolong intrauterine maturity while reducing the risks of stillbirth. Many of these strategies involve complex interpretation, for example Doppler ultrasound for fetal blood flow and computerized analysis of fetal heart rate changes. However, even with these modalities of fetal assessment to determine the optimal timing of delivery, fetal movements remain integral to clinical decision-making. In high-risk cohorts with fetal growth restriction, the manifestation of a reduction in perceived movements may warrant an expedited delivery. Despite this, there has been little evolution in the development of technologies to objectively evaluate fetal movement behavior for clinical application. This review explores the available literature on the value of fetal movement analysis as a method of assessing fetal wellbeing, and demonstrates how interdisciplinary developments in this area may aid in the improvement of clinical outcomes.

Prediction of the risk of cesarean delivery after labor induction in twin gestations based on clinical and ultrasound parameters

AIMS

To develop a model based on clinical and ultrasound parameters to predict the risk of cesarean delivery after labor induction in near-term twin gestations.

METHODS

This retrospective cohort study included 189 consecutive women with twin gestations at ≥ 36.0 weeks scheduled for labor induction. The Bishop score and transvaginal ultrasonographic measurements of cervical length were obtained immediately before labor induction. Parameters studied included maternal age, height, weight, parity, gestational age, Bishop score, cervical length, epidural analgesia, method of conception, chorionicity and birth weight. Prostaglandin E2 (dinoprostone) and oxytocin were used for labor induction. Logistic regression analysis and receiver operating characteristic curve were used to generate a predictive model for cesarean delivery.

RESULTS

Fifty (26.5%) of the 189 women had cesarean deliveries. According to logistic regression analysis, maternal height (P = 0.004), parity (P = 0.005) and cervical length (P = 0.016), but not Bishop score (P = 0.920), were identified as independent predictors of cesarean delivery. A risk score based on a model of these three parameters was calculated for each patient. The model was shown to have an adequate goodness of fit (P = 0.201) and the area under the curve was 0.722, indicating fairly good discrimination.

CONCLUSIONS

Maternal height, parity and cervical length were independent parameters for predicting the risk of cesarean delivery after labor induction in twin gestations. A predictive model using these parameters may provide useful information for deciding whether or not to induce labor.

Clinical and sonographic parameters at mid-trimester and the risk of cesarean delivery in low-risk nulliparas

BACKGROUND

To examine the potential clinical and sonographic parameters at mid-trimester that predict the risk of intrapartum cesarean delivery at term among low-risk nulliparas.

METHODS

This prospective study recruited nulliparas with singleton low-risk pregnancies at 20.0-24.0 weeks. Sonographic measurement of the cervical length and fetal biometry was performed. The data collected at enrollment included maternal age, measured weight at first prenatal visit to the hospital, current weight, height, fetal biometric parameters, and cervical length. A multivariate analysis was conducted, with control for known intra- and postpartum confounding factors associated with cesarean delivery, including sex of the fetus.

RESULTS

Based on multivariate analyses of 652 women, of all variables at mid-trimester, only maternal height was significantly associated with increased risk of cesarean delivery (61, 9.4%), whereas for intra- or postpartum variables, induction of labor, epidural analgesia, male gender, and nightshift delivery showed statistically significant association with the risk of cesarean delivery.

CONCLUSIONS

Maternal height and fetal gender, as measured at mid-trimester, are potential independent predictors for the risk of intrapartum cesarean delivery at term in low-risk nulliparas; however, sonographic measurements of the cervical length, fetal biometric ratio, maternal age, and current weight at mid-trimester were not predictive of cesarean delivery at term. © 2014 Wiley Periodicals, Inc. J Clin Ultrasound 43:235-242, 2015.

Are we (mis)guided by current guidelines on intrapartum fetal heart rate monitoring? Case for a more physiological approach to interpretation

Original interpretations of fetal heart rate (FHR) patterns equated FHR decelerations with 'fetal distress', requiring expeditious delivery. This simplistic interpretation is still implied in our clinical guidelines despite 40 years of increasing understanding of the behaviour and regulation of the fetal cardiovascular system during labour. The physiological basis of FHR responses and adaptations to oxygen deprivation is de-emphasised, whilst generations of obstetricians and midwives are trained to focus on, and classify, the morphological appearances of decelerations into descriptive categories, with no attempt to understand how the fetus defends itself and compensates for intrapartum hypoxic ischaemic insults, or the patterns that suggest progressive loss of compensation. Consequently, there is a lack of confidence, marked variation in FHR interpretation, defensive practices, unnecessary operative interventions, and a failure to recognise abnormal FHR patterns, resulting in adverse outcomes and expensive litigation.

Understanding cardiotocographic patterns associated with intrapartum fetal hypoxia and neurologic injury

Widespread use of fetal heart rate monitoring for intrapartum fetal surveillance preceded our detailed understanding of the behaviour and regulation of the fetal cardiovascular system during labour. The fetal heart rate is sensitive to fetal hypoxaemia and hypoxia, but lacks specificity for fetal acidosis, the end point of unmitigated hypoxaemia and hypoxia. Original interpretations of fetal heart rate patterns equated decelerations to 'fetal distress' and mandated operative intervention. Since then, obstetricians have been trained to focus on the morphological appearances of fetal heart rate decelerations rather than to understand the underlying physiological mechanisms, how the fetus compensates and defends itself, and those patterns that suggest progressive loss of compensation. Consequently, operative interventions are commonly undertaken to 'rescue' fetuses that display benign signs of fetal heart rate adaption to events in labour. Failure to recognise abnormal fetal heart rate patterns remains the leading cause of avoidable brain injury and litigation. In this chapter the general characteristics of the fetal heart rate, the changes in fetal heart rate pattern that may occur during labour, and the patterns that suggest failure of the fetal compensatory mechanisms leading to injury are discussed.

Acidemia at birth in the vigorous infant as a trigger incident to assess intrapartum care with regard to CTG patterns

OBJECTIVE

To evaluate if acidemia in vigorous infants is a useful variable in the assessment of intrapartum care with regard to cardiotocographic (CTG) patterns during the second stage.

METHODS

Cases (n = 241) were infants with an umbilical artery pH < 7.05, controls (n = 482) were infants with pH ≥ 7.05. Apgar score was ≥ 7 at 5 min in both groups. CTGs during the last two hours of labor were assessed and neonatal outcomes compared. A sub-analysis of cases with metabolic acidemia: pH < 7.00 and base deficit ≥ 12 mmol/L and acidemia: 7.00 < pH < 7.05 was performed.

RESULTS

63% of cases had a pathological CTG versus 26% of controls (p < 0.001). Patterns with severe variable decelerations had a significantly longer duration in cases. Metabolic acidemia was significantly associated with severe variable decelerations and decreased variability. Infants to cases were admitted to neonatal care in 19% versus 2% of controls (p < 0.001). With metabolic acidemia, 32% were admitted.

CONCLUSION

An umbilical artery pH < 7.05 at birth of vigorous infants may be a useful variable for quality control of intrapartum management with regard to the assessment of second-stage CTGs. Differences in duration of pathological patterns indicate passiveness in academic cases.

[Cerebral palsy and perinatal asphyxia (I--diagnosis)]

Cerebral palsy (CP) is a group of disorders of the development of movement and posture, causing activity limitations, that are attributed to nonprogressing disturbances that occurred in the developing fetal or infant brain. The motor abnormalies are often accompanied by disturbances of sensation, perception, cognition, behavior and/or by a seizure disorder. The prevalence of CP has not decreased in developed countries over the past 30 years, despite the widespread use of electronic fetal heart rate monitoring and a 5- to 6-fold increase in the cesarean delivery rate. In the term newborn, CP may be attributed to perinatal asphyxia in case of metabolic acidosis in the cord blood (pH<7,00 and base deficit>12 mmol/L), followed by a moderate or severe neonatal encephalopathy within 24 hours and a further neurological impairement characterized by spastic quadriplegia and dyskinesia/dystonia. Dating the time of fetal asphyxia during delivery is possible when there are acute catastrophic complications during labor and unexpected acute or progressive fetal heart rate anomalies after a normal admission test, when there is a need for intensive neonatal resuscitation, a multi-organ failure within 72 hours of birth and visualization of acute non focal cerebral abnormalities, mainly by early magnetic resonance imaging (MRI). MRI sequences show either a brain-damaged pattern of the central basal ganglia, thalami and posterior limbs of internal capsules with relative cortical sparing, in acute, near-total asphyxial insults manifested by a continuous bradycardia or a pattern of cortical injury in the watershed zones and relative sparing of the central grey matter, in prolonged partial asphyxia, manifested by late or atypical variable decelerations with progressive fetal tachycardia, loss of reactivity and absent fluctuation. Prolongation of either type of asphyxial insult results in more global brain damage. In order to differentiate a CP occurring after perinatal asphyxia from other neurological sequelae in relation with infection, hemorrhage, stroke, malformations, genetic or metabolic diseases, it is essential that a definitive information from the brain by MRI and an extensive histological examination of the placenta are at disposal.

Fetal acidemia and electronic fetal heart rate patterns: Is there evidence of an association?

OBJECTIVE

Despite the ubiquity of electronic fetal monitoring, the validity of the relationship between various fetal heart rate (FHR) patterns and fetal acidemia has not yet been established in a large unselected series of consecutive pregnancies. The aim of this study was to examine the published literature for evidence of such a relationship.

METHODS

Four hypotheses based on assumptions in common clinical use were examined. The literature was searched for relationships between certain aspects of FHR patterns (e.g., degree of FHR variability, depth of decelerations), and fetal acidemia, or fetal vigor (5-minute Apgar score >or=7). We also attempted to relate duration of these patterns to the degree of acidemia. Using standardized FHR nomenclature we defined patterns based on baseline FHR variability, baseline rate, decelerations, and accelerations.

RESULTS

The following relationships were observed: (1) Moderate FHR variability was strongly associated (98%) with an umbilical pH >7.15 or newborn vigor (5-minute Apgar score >or=7). (2) Undetectable or minimal FHR variability in the presence of late or variable decelerations was the most consistent predictor of newborn acidemia, though the association was only 23%. (3) There was a positive relationship between the degree of acidemia and the depth of decelerations or bradycardia. (4) Except for sudden profound bradycardia, newborn acidemia with decreasing FHR variability in combination with decelerations develops over a period of time approximating one hour. Most studies identified were observational and uncontrolled (grade III evidence of US Preventive Services Task Force); however, there was general agreement amongst the various studies, strengthening the validity of the observations.

CONCLUSIONS

The validity of the relationship between certain FHR patterns and fetal acidemia and/or vigor, is supported by observations from the literature. In addition four assumptions commonly used in clinical management are supported. These conclusions need to be confirmed by a prospective examination of a large number of consecutive, unselected FHR patterns, and their relationship to newborn acidemia. Pending the completion of such studies, these observations can be used to justify certain aspects of current clinical management, and may assist in standardizing the diversity of opinions regarding FHR pattern management.

Cesarean section for suspected fetal distress, continuous fetal heart monitoring and decision to delivery time

OBJECTIVE

To find out the efficacy of continuous fetal heart monitoring by analyzing the cases of cesarean section for nonreassuring fetal heart in labor, detected by cardiotocography (CTG) and correlating these cases with perinatal outcome. To evaluate whether a 30 minute decision to delivery (D-D) interval for emergency cesarean section influences perinatal outcome.

METHODS

This was a prospective observational study of 217 patients who underwent cesarean section at > or = 36 weeks for non-reassuring fetal heart in labor detected by CTG. The maternal demographic profile, specific types of abnormal fetal heart rate tracing and the decision to delivery time interval were noted. The adverse immediate neonatal outcomes in terms of Apgar score <7 at 5 minutes, umbilical cord thornH <7.10, neonates requiring immediate ventilation and NICU admissions were recorded. The correlation between non-reassuring fetal heart, decision to delivery interval and neonatal outcome were analyzed.

RESULTS

Out of 3148 patients delivered at > or = 36 weeks, 217 (6.8%) patients underwent cesarean section during labor primarily for non-reassuring fetal heart. The most common fetal heart abnormality was persistent bradycardia in 106 (48.8%) cases followed by late deceleration in 38 (17.5%) cases and decreased beat to beat variability in 17 (7.8%) cases. In 33 (15.2%) babies the 5 minutes Apgar score was <7 out of which 13 (5.9%) babies had cord thornH <7.10. Thirty three (15.2%) babies required NICU admission for suspected birth asphyxia. Rest 184 (84.7%) neonates were born healthy and cared for by mother. Regarding decision to delivery interval of < or =30 minutes versus >30 minutes, there was no significant difference in the incidence of Apgar score <7 at 5 minutes, cord pH <7.10 and new born babies requiring immediate ventilation. But the need for admission to NICU in the group of D-D interval < or = 30 minutes was significantly higher compared to the other group where D-D interval was >30 minutes.

CONCLUSION

Non-reassuring fetal heart rate detected by CTG did not correlate well with adverse neonatal outcome. There was no significant difference in immediate adverse neonatal outcome whether the D-D time interval was < or = 30 minutes or >30 minutes; contrary to this, NICU admission for suspected birth asphyxia in </= 30 minutes group was significantly higher.

[Fetal heart rate during labour: definitions and interpretation]

Continuous fetal heart rate monitoring is widely used during labor even in low risk pregnancies. Consensus is necessary to define and interpret accurately the different FHR patterns. The normal FHR tracing include baseline rate between 110-160 beats per minute (bpm), moderate variability (6-25 bpm), presence of accelerations and no decelerations. Uterine activity is monitored simultaneously: contractions frequency, duration, amplitude and relaxation time must be also normal. Abnormal baseline heart rate during 10 minutes or more is termed tachycardia above 160 bpm (except for FIGO above 150) and bradycardia below 110 bpm. Variability is minimal below 6 bpm and absent when non visible. Decelerations are classified as early, variable, late, and prolonged. Early and late decelerations have an onset gradual decrease of FHR, in contrast variable decelerations have an abrupt onset. Early deceleration is coincident in timing with uterine contraction. Variable deceleration is variable in onset, duration and timing, and may be described as typical or non reassuring. Late deceleration is associated with uterine contraction; the onset, nadir, and recovery occur after onset, peak and end of the contraction. Prolonged deceleration is lasting more than two but less 10 minutes, with almost onset abrupt and no repetition. Electronic fetal monitoring is a method to detect risk of fetal asphyxia; analysis and interpretation of FHR patterns are difficult with a high false positive rate, increasing operative deliveries. The patterns who are predictive of severe fetal acidosis include recurrent late or variable or prolonged decelerations or bradycardia, with absent FHR variability, and sudden severe bradycardia. The other FHR patterns are not conclusive and defined as non reassuring; obstetrical risk factors must be considered and other method (like scalp sampling for pH) utilised to evaluate fetal state.

Intrauterine asphyxia: clinical implications for providers of intrapartum care

Advances in science and technology have allowed researchers to gain a better understanding of the pathophysiology leading to long-term neurologic damage in newborns. Intrapartum events are now known to be an infrequent cause of adverse neurologic outcome. Clinicians caring for women during labor must have an understanding of the pathophysiology of intrauterine asphyxia as well as an awareness of the capabilities and limitations of available intrapartum fetal assessment tools to diagnose intrauterine fetal asphyxia or predict neurologic outcome. This article reviews the physiology of acid-base balance and fetal gas exchange as well as the current scientific understanding of the role of intrauterine asphyxia in the pathophysiology of neonatal encephalopathy and cerebral palsy. Recommendations for care and documentation are included.

Fetal hypoxic and ischemic injuries

PURPOSE OF REVIEW

The principles of neonatal neurological protection following intrapartum hypoxia are briefly reviewed. The physiological principles behind the use of cardiotocograph patterns in defining the timing and mechanism of fetal hypoxia and injury are then demonstrated.

RECENT FINDINGS

Fetal neurological injury may result from progressive hypoxemia, acidosis, diminished cardiac output and cerebral ischemia, manifested at birth as low Apgar scores, multisystem compromise, severe acidosis and encephalopathy. More commonly, however, intrapartum injury results from often intermittent, regional ischemia secondary to umbilical cord or head compression resulting in hemorrhage or infarction. Under these circumstances, the amount of umbilical acidosis and neonatal encephalopathy varies and the potential candidate for neuroprotection may escape recognition and timely treatment. Selecting infants likely to benefit from neuroprotection requires information on the timing, duration and mechanism of hypoxia. Neonatal parameters, including low Apgar scores, acidosis, even seizures, lack sensitivity and specificity. Cardiotocograph patterns are capable of determining the duration, mechanism and severity of hypoxia and occasionally, the timing of neurological injury.

SUMMARY

Protecting the newborn from the neurological consequences of intrapartum hypoxia requires critical definition of the mechanism and timing of this exposure. cardiotocograph tracings offer the opportunity to refine the selection of candidates for neonatal rescue.

Cesarean Delivery for Nonreassuring Fetal Heart Rate Tracing

An understanding of cesarean delivery for nonreassuring fetal heart rate tracing is important for several reasons. This article describes the prevalence of cesarean for nonreassuring fetal heart rate tracing and risk factors, indicates what type of fetal heart rate tracing abnormalities prompts cesarean delivery, reiterates the intrauterine resuscitation that the American College of Obstetricians and Gynecologists guidelines, and suggests steps clinicians should undertake to minimize legal liability.

Fetal assessment in the adult intensive care unit

Ideally the clinical management of a critically ill pregnant woman is based on a collaborative approach with members of the ICU and perinatal team each contributing their expertise to promote the best out-come for the mother and baby. The interdisciplinary team also should include anesthesia providers and neonatal specialists. The physical space (ICU or labor and delivery unit) is less important than the quality and coordination of the care and treatment. The responsibility for fetal assessment when the woman is critically ill should rest with those who have this expertise. Working together provides the best opportunity for optimal outcomes.

Intrapartum fetal heart rate patterns in the prediction of neonatal acidemia

OBJECTIVE

This study was undertaken to correlate changes in the intrapartum electronic fetal heart rate patterns with the development of significant neonatal acidemia.

STUDY DESIGN

We identified 488 fetuses at a gestational age of >37 weeks' gestation who had continuous electronic fetal monitoring during labor for the last 2 hours and umbilical artery cord gas analysis performed at delivery. One investigator blinded to the cord gas outcome reviewed all 488 tracings using the National Institute of Child Health and Human Development guidelines for fetal heart rate monitoring. All fetal heart rate tracings with bradycardia were removed from further analysis. The patients were placed in six groups, depending on the absence or presence of normal variability (amplitude >5 beats) during the last hour of monitoring combined with the absence of decelerations or the presence of variable or late decelerations. The relationship between changes in variability and the outcome variables of pH and base deficit in the six groups was assessed with analysis of variance and chi(2) test. Significance was set at the P <.05 level.

RESULTS

Patients with normal variability and accelerations, even in the presence of late decelerations or variable decelerations, maintained an umbilical artery pH 7.0 or greater in more than 97% of cases. In the presence of minimal/absent variability (amplitude <5) for at least an hour, the incidence of significant acidemia (pH <7.0) ranged from (12%-31%).

CONCLUSION

The most significant intrapartum fetal heart rate parameter to predict the development of significant acidemia is the presence of minimal/absent variability for at least 1 hour as a solitary abnormal finding or in conjunction with late decelerations in the absence of accelerations. Urgent delivery should be considered in these cases after appropriate ancillary testing.

Fetal heart rate and survival of the very premature newborn

OBJECTIVE

Our purpose was to study the likelihood of survival of infants who are born before 28 weeks of gestation and to examine the influence of fetal heart rate findings on neonatal death.

STUDY DESIGN

In this retrospective study, we analyzed the mortality rate of infants at 2 months of age as a function of various obstetric and prenatal indicators.

RESULTS

At 2 months, 207 of 325 children were still alive. The survival rate was also a function of gestational age, birth weight, the administration of corticosteroids, multiple pregnancies, and fetal heart rate. Fetal heart rate had the greatest effect on the mortality rate. Children with a reactive rate were 4 times more likely to survive than children with a flat tracing (P =.003; odd ratio, 4; 95% CI, 12.1; 39.8).

CONCLUSION

The results in our study lead us to think that recording the fetal heart rate before and during labor may be useful in the prediction of perinatal death and may help obstetric decision-making.

Use of umbilical artery base excess: algorithm for the timing of hypoxic injury

Intrapartum asphyxia is responsible for only a small proportion of cerebral palsy cases, although obstetricians are often held accountable. Umbilical cord pH and blood gas values provide valuable information regarding the status of the infant at birth; base excess determination quantifies the magnitude of metabolic acidosis, the putative risk factor for central neurologic injury. Human and animals studies have confirmed normal values of base excess before labor, and consistent rates of base excess change in relation to the degree of fetal hypoxemia or heart rate patterns. Thus, the combination of assumed base excess values before labor and measured values after birth, together with an assessment of degrees of fetal hypoxemia during labor, permits an interpolation of fetal base excess values throughout the course of labor. Because threshold levels of base excess (eg, -12 mmol/L) have been associated with an increased risk of neonatal neurologic injury, this approach provides a framework for the assessment of fetal heart rate tracings during labor and, potentially, the timing of hypoxic/ischemic injury.

The physiology of fetal heart rate patterns and perinatal asphyxia

The purpose of electronic fetal heart rate (FHR) monitoring is the ongoing assessment of fetal oxygenation. FHR tracings are analyzed for characteristic patterns that signify specific hypoxic or nonhypoxic events. A working knowledge of fetal physiology and the fetal response to hypoxia can aid and refine clinical interpretation of FHR patterns during labor. This article reviews the fetal response to decreased oxygenation, the physiology of subsequent FHR patterns and the clinical presentation of asphyxia in the newborn.

Intrapartum fetal heart rate monitoring

Intrapartum fetal heart rate monitoring is commonly used to evaluate fetal status in labor, despite a lack of convincing randomized studies to support its use. The National Institutes of Health have helped standardize fetal heart rate monitoring terminology with their 1997 task force report, which will aid clinicians and scientists in their goal of providing quality care and research. The American College of Obstetricians and Gynecologists has recommended the term nonreassuring fetal status for electronic fetal monitor patterns that are not normal; however, Vanderbilt continues to use the terms fetal stress and fetal distress, using specific criteria for each. The approximately 30% of fetal heart rate tracings labeled as fetal stress (or nonreassuring fetal status) can be evaluated further by the use of fetal pulse oximetry, a new technology currently under evaluation in this country.