A framework for standardized management of intrapartum fetal heart rate patterns

Agreement on intrapartum cardiotocogram recordings between expert obstetricians

RATIONALE, AIMS AND OBJECTIVES

To evaluate obstetricians' inter- and intra-observer agreement on intrapartum cardiotocogram (CTG) recordings and to examine obstetricians' evaluations with respect to umbilical artery pH and base deficit.

METHODS

Nine experienced obstetricians annotated 634 intrapartum CTG recordings. The evaluation of each recording was divided into four steps: evaluation of two 30-minute windows in the first stage of labour, evaluation of one window in the second stage of labour and labour outcome prediction. The complete set of evaluations used for this experiment is available online. The inter- and intra-observer agreement was evaluated using proportion of agreement and kappa coefficient. Clinicians' sensitivity and specificity was computed with respect to umbilical artery pH, base deficit and to Apgar score at the fifth minute.

RESULTS

The overall proportion of agreement between clinicians reached 48% with 95% confidence intervals (CI) (CI: 47-50). Regarding the different classes, proportion of agreement ranged from 57% (CI: 54-60) for normal to 41% (CI: 36-46) for pathological class. The sensitivity of clinicians' majority vote to objective outcome was 39% (CI: 16-63) for the umbilical artery base deficit and 27% (CI: 16-42) for pH. The specificity was 89% (CI: 86-92) for both types of objective outcome.

CONCLUSIONS

The reported inter-/intra-observer variability is large and this holds irrespective of clinicians' experience or work place. The results support the need of modernized guidelines for CTG evaluation and/or objectivization and repeatability by introduction of a computerized approach that could standardize the process of CTG evaluation within the delivery ward.

Biphasic changes in fetal heart rate variability in preterm fetal sheep developing hypotension after acute on chronic lipopolysaccharide exposure

Perinatal exposure to infection is highly associated with adverse outcomes. Experimentally, acute, severe exposure to gram-negative bacterial lipopolysaccharide (LPS) is associated with increased fetal heart rate variability (FHRV). It is unknown whether FHRV is affected by subclinical infection with or without acute exacerbations. We therefore tested the hypothesis that FHRV would be associated with hypotension after acute on chronic exposure to LPS. Chronically instrumented fetal sheep at 0.7 gestation were exposed to a continuous low-dose LPS infusion (n = 12, 100 ng/kg over 24 h, followed by 250 ng·kg(-1)·24 h(-1) for a further 96 h) or the same volume of saline (n = 10). Boluses of either 1 μg LPS or saline were given at 48, 72, and 96 h. Low-dose infusion was not associated with hemodynamic or FHRV changes. The first LPS bolus was associated with tachycardia and suppression of nuchal electromyographic activity in all fetuses. Seven of twelve fetuses developed hypotension (a fall in mean arterial blood pressure ≥5 mmHg). FHRV was transiently increased only at the onset of hypotension, in association with increased cytokine induction and electroencephalogram suppression. FHRV then fell before the nadir of hypotension, with transient suppression of short-term FHRV. After the second LPS bolus, the hypotension group showed a biphasic pattern of a transient increase in FHRV followed by more prolonged suppression. These findings suggest that infection-related hypotension in the preterm fetus mediates the transient increase in FHRV and that repeated exposure to LPS leads to progressive loss of FHRV.

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.

Utility of intraoperative fetal heart rate monitoring for cerebral arteriovenous malformation surgery during pregnancy

We report two methods of intraoperative fetal heart rate (FHR) monitoring in cases of cerebral arteriovenous malformation surgery during pregnancy. In one case in her third trimester, cardiotocography was used. In another case in her second trimester, ultrasound sonography was used, with a transesophageal echo probe attached to her lower abdomen. Especially, the transesophageal echo probe was useful because of the advantages of being flexible and easy to attach to the mother's lower abdomen comparing with the usual doppler ultrasound probe. In both cases, the surgery was successfully performed and FHR was monitored safely and stably. The use of intraoperative FHR monitoring provides information about the influence of induced maternal hypotension and unexpected bleeding on fetus during surgery. These monitoring techniques would be especially emphasized in cerebrovascular surgery for the safe management of both mother and fetus.

Normal and indeterminate pattern of fetal cardiotocography in admission test and pregnancy outcome

AIM

The aim of this study was to evaluate the prognostic value of normal and indeterminate patterns of cardiotocography in admission test (AT) and pregnancy outcome.

MATERIAL AND METHODS

A prospective study enrolled 818 intrapartum singleton pregnancies with gestational age of >34 weeks, in the latent phase and with intact membrane. Cases were divided into the high- and low-risk groups. Non-Stress Test was interpreted according to the 2008 National Institute of Child Health and Human Development workshop. Adverse pregnancy outcomes were compared between groups based on AT interpretation.

RESULTS

Out of 818 patients, 492 (60%) were categorized as low-risk and 326 (40%) as high-risk pregnancies. In low-risk patients, 410 (83.3%) had normal and 82 (16.7%) had indeterminate AT. These figures were 249 (76.4%) and 77 (23.6%) in high-risk patients, respectively, and two cases (0.6%) had abnormal AT. In both groups, thick meconium staining, non-reassuring fetal heart rate pattern, cesarean section and cesarean section due to non-reassuring fetal heart rate pattern were significantly more frequent in indeterminate AT than normal ones (P < 0.001). In high-risk pregnancies with indeterminate AT, the risk of low birthweight and neonatal intensive care unit (NICU) admission increased. The positive predictive value was less than 30% in predicting thick meconium staining, non-reassuring fetal heart rate pattern, PH ≤ 7.2 and NICU admission in both groups. Overall, negative predictive value of AT for neonatal death and NICU admission was 100% and 96%, respectively.

CONCLUSIONS

Indeterminate patterns of cardiotocography can predict adverse pregnancy outcomes and when facing this condition, obstetricians should act cautiously.

Analysis of obstetricians' decision making on CTG recordings

Interpretation of cardiotocogram (CTG) is a difficult task since its evaluation is complicated by a great inter- and intra-individual variability. Previous studies have predominantly analyzed clinicians' agreement on CTG evaluation based on quantitative measures (e.g. kappa coefficient) that do not offer any insight into clinical decision making. In this paper we aim to examine the agreement on evaluation in detail and provide data-driven analysis of clinical evaluation. For this study, nine obstetricians provided clinical evaluation of 634 CTG recordings (each ca. 60min long). We studied the agreement on evaluation and its dependence on the increasing number of clinicians involved in the final decision. We showed that despite of large number of clinicians the agreement on CTG evaluations is difficult to reach. The main reason is inherent inter- and intra-observer variability of CTG evaluation. Latent class model provides better and more natural way to aggregate the CTG evaluation than the majority voting especially for larger number of clinicians. Significant improvement was reached in particular for the pathological evaluation - giving a new insight into the process of CTG evaluation. Further, the analysis of latent class model revealed that clinicians unconsciously use four classes when evaluating CTG recordings, despite the fact that the clinical evaluation was based on FIGO guidelines where three classes are defined.

Intrapartum management of category II fetal heart rate tracings: towards standardization of care

There is currently no standard national approach to the management of category II fetal heart rate (FHR) patterns, yet such patterns occur in the majority of fetuses in labor. Under such circumstances, it would be difficult to demonstrate the clinical efficacy of FHR monitoring even if this technique had immense intrinsic value, since there has never been a standard hypothesis to test dealing with interpretation and management of these abnormal patterns. We present an algorithm for the management of category II FHR patterns that reflects a synthesis of available evidence and current scientific thought. Use of this algorithm represents one way for the clinician to comply with the standard of care, and may enhance our overall ability to define the benefits of intrapartum FHR monitoring.

Fetal heart rate classification proposed by the perinatology committee of the Japan Society of Obstetrics and Gynecology: reproducibility and clinical usefulness

AIM

Intrapartum management guidelines based on fetal heart rate classification comprising a 5-tier system (Levels 1-5) was proposed by the Perinatology Committee of the Japan Society of Obstetrics and Gynecology (JSOG). This study aimed to assess the reproducibility and clinical usefulness of this classification.

METHODS

For assessing intraobserver and interobserver reproducibility in the interpretation of fetal heart rate tracing, 2 obstetricians reviewed 247 fetal heart rate tracings using the JSOG classification (Level 1, normal; Level 2, benign variant; Level 3, mild variant; Level 4, moderate variant; and Level 5, severe variant) and a subjective 3-tier classification (normal, equivocal, and ominous). In a separate series, we investigated whether the JSOG classification is related to early neonatal outcome and the delivery mode in 96 deliveries.

RESULTS

Weighted kappa coefficients of intraobserver and interobserver reproducibility in the interpretation of fetal heart rate tracings based on the JSOG classification were 0.73 to 0.77 and 0.70, respectively. In the subjective classification, these values were 0.69 to 0.72 and 0.59. There was a progressive increase in the rate of instrumental or cesarean deliveries across the 5 levels of the JSOG classification (P<0.001). Although, level 5 of the JSOG classification had a lower Apgar score and umbilical artery pH than did the other 4 levels (p<0.05), there were no significant differences among the other levels in regard to early neonatal outcome.

CONCLUSIONS

This study demonstrated that both intraobserver reproducibility and interobserver reproducibility of the JSOG classification for interpreting FHR tracings were clinically acceptable. The results also suggest that the intervention according to the JSOG classification is useful for avoiding worsening early neonatal outcomes.

The conundrum of vanishing early decelerations in British obstetrics, a step backwards? Detailed appraisal of British and American classifications of fetal heart rate decelerations - fallacies of emphasis on waveform and putative aetiology

A recent opinion survey of British Obstetricians revealed 'early' fetal heart rate (FHR) decelerations as the commonest type in their practice. This contrasts with the guidelines by the National Institute for Health and Clinical Excellence, UK (NICE 2007) that 'true uniform early decelerations are rare and most decelerations are variable'. This analytical review suggests that the emphasis on putative aetiology and 'waveform' of decelerations by NICE and other national guidelines leads to fundamental inconsistencies. 'Uniform shape' is misinterpretation of the description by Hon and Quilligan (1968). Truly 'uniform' (identical)) decelerations do not occur and no examples can be found. Gradual ('bell') or rapid shape has no correlation to putative causation or fetal condition. Obstetricians and midwives should seek clarification of these fallacies. The previous British practice of classifying decelerations based solely on time relationship to contractions seems most scientifically robust leading to more consistent interpretation and better discrimination of fetal status.

Comparison of five classification systems for interpreting electronic fetal monitoring in predicting neonatal status at birth

OBJECTIVE

To compare the accuracy of five different classification systems for interpreting electronic fetal monitoring (EFM) when predicting neonatal status at birth, as determined by the umbilical cord arterial pH.

METHODS

Ninety-seven cardiotocography traces were retrospectively interpreted according to five classification systems for EFM: Dublin Fetal Heart Rate Monitoring Trial (DFHRMT), Royal College of Obstetricians and Gynecologists (RCOG), Society of Obstetricians and Gynaecologists of Canada (SOGC), National Institute of Child Health and Human Development (NICHD) and Parer & Ikeda's. For each classification system, sensitivity, specificity, positive and negative predictive values were calculated. The capacity of the classifications to predict neonatal pH was also evaluated by receiver-operating characteristic (ROC) curves. Agreement between the five systems was estimated using weighted kappa statistic.

RESULTS

Considering pH ≤7.15 as the cutoff for low pH, the sensitivity and specificity values were 100 and 18% (DFHRMT); 100 and 15% (RCOG); 88 and 37% (SOGC); 67 and 92% (NICHD); 55 and 67% (Parer & Ikeda). The ROC curves showed that all classifications analyzed had a low discriminative capacity when predicting umbilical artery pH ≤7.15. An excellent agreement was observed between DFHRMT and RCOG (weighted κ value: 0.860).

CONCLUSIONS

Parer & Ikeda and NICHD classifications had the highest specificity in detecting umbilical cord arterial pH ≤7.15. The high specificity of the NICHD classification is hindered by a high percentage of "intermediate" traces (80%). Parer & Ikeda classification is the one that best classify as pathological only the traces of fetuses that are truly at risk of acidemia, thus avoiding unnecessary intervention. It also showed the best trade-off between sensitivity and specificity and the lowest rate of traces considered "intermediate."

The significance of amplitude and duration of fetal heart rate acceleration in non-stress test analysis

OBJECTIVE

This study was conducted to assess the relative significance of the amplitude versus the duration of accelerations in non-stress test (NST) analysis.

MATERIALS AND METHODS

A total of 3055 normal fetal heart rate (FHR) tracings at 30-42 weeks' gestation were analyzed by automated FHR analyzing software. Accelerations were classified as one of four combinations of amplitude and duration: 15 bpm-15 seconds (Acc15-15), 15 bpm-10 seconds (Acc15-10), 10 bpm-15 seconds (Acc10-15) and 10 bpm-10 seconds (Acc10-10). We estimated the correlation among the FHR acceleration combinations using correlation analysis based on linear regression models.

RESULTS

Linear regression models demonstrated statistically significant linear associations between Acc15-15 and Acc15-10 (r(2) = 0.998, p < 0.0001) and between Acc10-10 and Acc10-15 (r(2) = 0.989, p < 0.0001). There was significant association based on amplitude and relatively low correlation based on duration (Pearson correlation coefficient = 0.99 between Acc10-10 and Acc10-15, and 0.99 between Acc15-15 and Acc15-10). In the relationships of the FHR-work values, amplitude was a more important component of FHR acceleration than duration [Acc10-10 (1.67 beat) < Acc10-15 (2.50 beats) = Acc15-10 (2.50 beats) < Acc15-15 (3.75 beats)].

CONCLUSION

Amplitude was a more significant component of FHR acceleration than duration in the computerized analysis of NST.

Preventing primary cesarean sections: intrapartum care

Some intrapartum care practices promote vaginal birth, whereas others may increase the risk for cesarean section. Electronic fetal monitoring and use of the Friedman graph to plot and monitor labor progress are associated with increasing the cesarean section rate. Continuous one-to-one support and midwifery management are associated with lower cesarean section rates. This article reviews the evidence that links specific intrapartum care practices to cesarean section. Strategies that can be implemented in the current social and cultural setting of obstetrics today are recommended.

Association and prediction of neonatal acidemia

OBJECTIVE

The objective of this study was to estimate the predictive ability of electronic fetal monitoring (EFM) patterns immediately prior to delivery for acidemia at term birth.

STUDY DESIGN

This was a 4-year retrospective cohort study of 5388 consecutive singleton, nonanomalous gestations of 37 weeks or longer. The primary exposure was the EFM pattern in the 30 minutes preceding delivery. EFM patterns were prospectively interpreted using Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) nomenclature as well as non-NICHD measurements of decelerations. The primary outcome was umbilical cord arterial pH of 7.10 or less.

RESULTS

Four NICHD-defined EFM features within the 30 minutes prior to birth demonstrated the greatest association with acidemia: repetitive prolonged decelerations (area under the curve [AUC] 0.81), baseline tachycardia (AUC 0.80), repetitive variable decelerations (AUC 0.79), and repetitive late decelerations (0.78) after adjusting for nulliparity, fever, prolonged first stage, and obesity. A non-NICHD measure, total deceleration area, demonstrated superior predictive ability for acidemia (AUC 0.83, P = .04).

CONCLUSION

A non-NICHD measure of deceleration frequency and severity in the second stage performed superior to 4 NICHD EFM features for predicting fetal acidemia.

The 5-tier system of assessing fetal heart rate tracings is superior to the 3-tier system in identifying fetal acidemia

OBJECTIVE

Electronic fetal heart rate monitoring was developed to identify fetuses at risk of acidemia for intervention before adverse outcomes. Our objective was to compare the 3-tier system with a 5-tier system in evaluation of fetal acidemia.

STUDY DESIGN

Retrospective case-control study of patients with a fetal arterial pH <7 matched to the next birth that resulted in a pH >7.2. Tracings were categorized into 3- and 5-tier systems by a single reviewer. Sensitivities and specificities were calculated for each.

RESULTS

Twenty-four cases and 24 controls were identified. The sensitivity for an orange or red tracing was higher than for category III, with more of these in the pH <7 group compared with controls (P ≤ .001). There were significantly more green, blue, and yellow tracings in the normal pH group compared with the pH <7 group (P = .033, P = .008, P = .023), respectively.

CONCLUSION

The 5-tier system had a better sensitivity than the 3-tier system.

Observation on validity of the five-tier system for fetal heart rate pattern interpretation proposed by Japan Society of Obstetricians and Gynecologists

OBJECTIVE

To evaluate the five-tier classification of fetal heart rate (FHR) tracings recently proposed by Japan Society of Obstetricians and Gynecologists (JSOG).

METHODS

The database between January and June 2009 was reviewed for women in active labor at ?36 + 0 gestational weeks, with singleton fetuses in cephalic presentation and with umbilical artery blood gas analyses. Continuous FHR tracings were assessed according to the five-tier classification proposed by JSOG, where level 1 is normal, level 2 is subnormal and levels 3?5 are abnormal patterns.

RESULTS

A total of 341 parturient women were eligible for this study protocol. The median (range) of the levels in the first and the second stage of labor were 1 (1-4) and 2 (1-4), respectively (p < 0.001). Both pH and base excess of umbilical artery decreased with higher levels of FHR tracings interpretation (p < 0.01). Interventions resulting in delivery were more necessary in the first stage of labor than in the second stage of labor in cases of levels 3 and more.

CONCLUSIONS

Five-tier system for FHR tracing interpretation proposed by JSOG intercorrelates with the fetal acid-base balance well. Categorization of FHR tracings by uniform diagnostic criteria will be useful to standardize therapeutic strategy by sharing common perception among obstetrical staff.

Assessment of the concordance among 2-tier, 3-tier, and 5-tier fetal heart rate classification systems

OBJECTIVE

In 2008, a National Institute of Child Health and Human Development/Society for Maternal-Fetal Medicine-sponsored workshop on electronic fetal monitoring recommended a new fetal heart tracing interpretation system. Comparison of this 3-tier system with other systems is lacking. Our purpose was to determine the relationships between fetal heart rate categories for the 3 existing systems.

METHODS

Three Maternal-Fetal Medicine specialists reviewed 120 fetal heart rates. All tracings were from term, singleton pregnancies with known umbilical artery pH. The fetal heart rates were classified by a 2-tier, 3-tier, and 5-tier system.

RESULTS

Each Maternal-Fetal Medicine examiner reviewed 120 fetal heart rate segments. When compared with the 2-tier system, 0%, 54%, and 100% tracings in categories 1, 2, and 3 were "nonreassuring." There was strong concordance between category 1 and "green" as well as category 3 and "red" tracings.

CONCLUSION

The 3-tier and 5-tier systems were similar in fetal heart rate interpretations for tracings that were either very normal or very abnormal. Whether one system is superior to the others in predicting fetal acidemia remains unknown.

Intrapartum cardiotocography (CTG) and ST-analysis of labor in diabetic patients

AIM

To determine the prevalence and types of intrapartum cardiotocography (CTG) patterns and investigate their relationship to moderate acidemia in term fetuses of diabetic mothers. Also, to assess if the combination of fetal electrocardiogram (FECG) and those CTG patterns strengthens the association with moderate acidemia.

MATERIAL AND METHODS

The material for this study is obtained from the Swedish randomized control trial and the European Union ST-analysis trial. We developed an analytical model for CTG patterns based on the progress in CTG changes, in a longitudinal periodic manner. The model was then combined with information regarding changes in ST interval that indicate threatening asphyxia, and the findings were analyzed to determine correlation with the presence of moderate acidemia at birth.

RESULTS

This study involved data of 413 diabetic mothers. A preterminal CTG was more common in the diabetes mellitus (DM) group (6/70, 8.6%) than in the gestational diabetes (GD) group (3/307, 1.0%; P=0.003). For diabetic mothers (i.e., DM+GD) with a normal CTG at the start of monitoring, the presence of FECG data indicating asphyxia significantly increased the likelihood of an umbilical artery pH<7.15 at birth [odds ratio (OR)=3.65, 95% confidence interval (CI)=1.33-10.05]. Among labors where the CTG was non-reassuring at the start of monitoring, no significant association was found between pH<7.15 and indication to intervene according to FECG information (OR=1.51, 95% CI=0.33-7.0).

CONCLUSIONS

A preterminal CTG is more common in the fetuses of DM than GD mothers during labor. When CTG was normal at the start of recording, the addition of FECG information gave a significant add on information to predict moderate acidemia.

P.U.R.E. (purposeful, unambiguous, respectful, and effective) Conversations and electronic fetal monitoring: gaining consensus and collaboration

A revised nomenclature regarding electronic fetal heart rate monitoring was accepted at a National Institute of Child Health and Human Development consensus conference in 2008. At the heart of patient safety are communication strategies that enhance teamwork and collaboration between health care professionals. Communications is a complex 2-way process that involves more than transfer of factual information. P.U.R.E. (purposeful, unambiguous, respectful, and effective) Conversations in Obstetrics is an acronym that helps facilitate this communication process in perinatal care. P.U.R.E. stands for purposeful, unambiguous, respectful, and effective. The P.U.R.E. Conversations approach involves refinement of the mental processes associated with delivering the message, delivery of the message with data, accuracy, and direct requests for action, attention to relationships and behaviors between the communicating parties, and real-time assessment of the effectiveness of the communication. When the new electronic monitoring nomenclature is combined with an effective communication tool, one could expect to see a reduction in communication failures that could lead to adverse perinatal outcomes.

Comparison of 5 experts and computer analysis in rule-based fetal heart rate interpretation

OBJECTIVE

The purpose of this study was to measure agreement among 5 expert clinicians and a computerized method with the use of a strict fetal heart rate classification method.

STUDY DESIGN

Five providers independently scored 769 8-minute segments from the last 3 hours of 30 tracings with the use of a 5-tier color-coded framework that contains pattern descriptions and proposals for management. Computer analysis was performed with PeriCALM Patterns (PeriGen, Princeton, NJ) to detect and classify patterns.

RESULTS

The clinicians agreed exactly with the majority opinion in 57% (95% confidence interval [CI], 49-64%) of the segments and were within 1 color code in 89% (95% CI, 81-96%). The average proportion of agreement was 0.83 (95% CI, 0.73-0.94). Weighted Kappa scores averaged 0.58 (range, 0.48-0.68). The computer-based results were not statistically different: 0.87 and 0.52, respectively.

CONCLUSION

These 5 clinicians achieved moderate-to-substantial levels of agreement overall using a strictly defined method to classify fetal heart rate tracings. The result of the computerized method was similar to the conclusions of these clinicians.

Graded classification of fetal heart rate tracings: association with neonatal metabolic acidosis and neurologic morbidity

OBJECTIVE

The objective of the study was to measure the performance of a 5-tier, color-coded graded classification of electronic fetal monitoring (EFM).

STUDY DESIGN

We used specialized software to analyze and categorize 7416 hours of EFM from term pregnancies. We measured how often and for how long each of the color-coded levels appeared in 3 groups of babies: (A) 60 babies with neonatal encephalopathy (NE) and umbilical artery base deficit (BD) levels were greater than 12 mmol/L; (I) 280 babies without NE but with BD greater than 12 mmol/L; and (N) 2132 babies with normal gases.

RESULTS

The frequency and duration of EFM abnormalities considered more severe in the classification method were highest in group A and lowest in group N. Detecting an equivalent percentage of cases with adverse outcomes required only minutes spent with marked EFM abnormalities compared with much longer periods with lesser abnormalities.

CONCLUSION

Both degree and duration of tracing abnormality are related to outcome. We present empirical data quantifying that relationship in a systematic fashion.

Probing the fetal cardiac signal for antecedents of brain injury

Obstetric care providers and researchers have long relied on analysis of the fetal heart rate tracing for insight into the fetal neurologic status. Although a normal fetal heart rate tracing does provide reassurance of intact neurologic function, an abnormal pattern is a very poor predictor of newborn brain injury. Indeed, if the clinical end point of interest is cerebral palsy, a non-reassuring fetal heart rate tracing has a 99% false positive rate. More recent analyses of fetal heart rate variability and fetal ECG waveforms, however, hold promise for improved diagnostic accuracy.

The fetal heart rate response to hypoxia: insights from animal models

This article examines recent studies that have systematically dissected features of fetal heart rate responses to labor that may help identify developing fetal compromise, such as the slope of the deceleration, overshoot, and variability. Although repeated deep decelerations are never necessarily benign, fetuses with normal placental reserve can fully compensate even for frequent deep but brief decelerations for surprisingly prolonged intervals before developing profound acidosis and hypotension.

Intrapartum fetal heart rate monitoring in cases of congenital heart disease

OBJECTIVE

We evaluated the intrapartum fetal heart rate (FHR) patterns in fetuses with congenital heart disease (CHD).

STUDY DESIGN

One hundred sixteen cases of fetal CHD were identified at our institute between 2000-2007; 464 fetuses without CHD were used as controls. The incidences of abnormal FHR patterns and umbilical blood gases were compared.

RESULTS

More fetuses with CHD showed variant FHR than did control fetuses (46.6% vs 17.7%; P < .01). Cesarean section deliveries that were based on fetal indications were performed more frequently in fetuses with CHD than in control fetuses (12.9% vs 3.2%; P < .01). Isomerism and tetralogy of Fallot were observed frequently with variant FHR. When chromosomal abnormalities and intrauterine growth restriction were excluded, the fetuses with CHD showed more variant FHR than did the control fetuses.

CONCLUSION

Fetuses with CHD are more likely to show abnormal FHR patterns than are control fetuses. We suggest that cardiac abnormalities are associated with abnormalities in FHR patterns.

The 2008 National Institute of Child Health and Human Development workshop report on electronic fetal monitoring: update on definitions, interpretation, and research guidelines

In April 2008, the Eunice Kennedy Shriver National Institute of Child Health and Human Development, the American College of Obstetricians and Gynecologists, and the Society for Maternal-Fetal Medicine partnered to sponsor a 2-day workshop to revisit nomenclature, interpretation, and research recommendations for intrapartum electronic fetal heart rate monitoring. Participants included obstetric experts and representatives from relevant stakeholder groups and organizations. This article provides a summary of the discussions at the workshop. This includes a discussion of terminology and nomenclature for the description of fetal heart tracings and uterine contractions for use in clinical practice and research. A three-tier system for fetal heart rate tracing interpretation is also described. Lastly, prioritized topics for future research are provided.