The second stage of labor.

The second stage of labor extends from complete cervical dilatation to delivery. During this stage, descent and rotation of the presenting part occur as the fetus passively negotiates its passage through the birth canal. Generally, descent begins during the deceleration phase of dilatation as the cervix is drawn upward around the fetal presenting part. The most common means of assessing the normality of the second stage of labor is to measure its duration, but progress can be more meaningfully gauged by measuring the change in fetal station as a function of time. Accurate clinical identification and evaluation of differences in patterns of fetal descent are necessary to assess second stage of labor progress and to make reasoned judgments about the need for intervention. Three distinct graphic abnormalities of the second stage of labor can be identified: protracted descent, arrest of descent, and failure of descent. All abnormalities have a strong association with cephalopelvic disproportion but may also occur in the presence of maternal obesity, uterine infection, excessive sedation, and fetal malpositions. Interpretation of the progress of fetal descent must be made in the context of other clinically discernable events and observations. These include fetal size, position, attitude, and degree of cranial molding and related evaluations of pelvic architecture and capacity to accommodate the fetus, uterine contractility, and fetal well-being. Oxytocin infusion can often resolve an arrest or failure of descent or a protracted descent caused by an inhibitory factor, such as a dense neuraxial block. It should be used only if thorough assessment of fetopelvic relationships reveals a low probability of cephalopelvic disproportion. The value of forced Valsalva pushing, fundal pressure, and routine episiotomy has been questioned. They should be used selectively and where indicated.

The active phase of labor.

The active phase of labor begins at various degrees of dilatation when the rate of dilatation transitions from the relatively flat slope of the latent phase to a more rapid slope. No diagnostic manifestations demarcate its onset, other than accelerating dilatation. It ends with apparent slowing of dilatation, a deceleration phase, which is usually short in duration and frequently undetected. Several aberrant labor patterns can be detected during the active phase, including protracted dilatation, arrest of dilatation, prolonged deceleration phase and failure of descent. Underlying factors may include cephalopelvic disproportion, excessive neuraxial block, poor uterine contractility, fetal malpositions, malpresentations, uterine infection, maternal obesity, advanced maternal age and previous cesarean delivery. When an active-phase disorder is identified, cesarean delivery is justifiable if there is compelling clinical evidence of disproportion. A prolonged deceleration disorder is strongly associated with disproportion and second stage abnormalities. Shoulder dystocia may occur if vaginal delivery eventuates. This review discusses several issues raised by the introduction of new clinical practice guidelines for labor management.

Dysfunctional labor and delivery: adverse effects on offspring.

There is no doubt that parturition can produce fetal and neonatal adversity, but the frequency with which this occurs is uncertain, particularly in modern healthcare settings. Moreover, there is a paucity of recent studies in this area. Substantial challenges impede epidemiologic study of the effect of parturition on offspring. Randomized trials would be ethically fraught. Therefore, large observational samples with detailed data concerning labor and delivery events are needed. Importantly, long-term follow-up of infants is necessary to reach reliable conclusions. Few such data sets exist, and it is difficult, expensive, and time-consuming to create and to study them. Reports of immediate newborn condition in relation to the antecedent labor are helpful, but this evidence is an imperfect predictor of long-term neurologic status. In this review, we endeavor to summarize existing information about the relationship between objectively defined abnormalities of labor progress and long-term disability in offspring. The only data available are from collected experiential information on outcomes stratified according to labor and delivery events. Most studies do not ensure against confounding by the many concurrent conditions that may affect outcome, or use inconsistent criteria to define abnormal labor. According to the best available evidence, dysfunctional labor patterns are potentially associated with poor outcomes for surviving infants. The question of whether these adverse effects can be mitigated by early diagnosis and expeditious management deserves to be answered, but cannot be at this time. In the absence of more conclusive results from well-designed studies, we can conclude that the best interests of offspring are served by adhering to evidence-based paradigms for the prompt identification and treatment of dysfunctional labor patterns.

The latent phase of labor.

The latent phase of labor extends from the initiation of labor to the onset of the active phase. Because neither margin is always precisely identifiable, the duration of the latent phase often can only be estimated. During this phase, the cervix undergoes a process of rapid remodeling, which may have begun gradually weeks before. As a consequence of extensive changes in its collagen and ground substance, the cervix softens, becomes thinner and dramatically more compliant, and may dilate modestly. All of these changes prepare the cervix for the more rapid dilatation that will occur during the active phase to follow. For the clinician, it is important to recognize that the latent phase may normally extend for many hours. The normal limit for the duration of the latent phase should be considered to be approximately 20 hours in a nullipara and 14 hours in a multipara. Factors that have been associated with a prolonged latent phase include deficient prelabor or intrapartum cervical remodeling, excessive maternal analgesia or anesthesia, maternal obesity, and chorioamnionitis. Approximately 10% of women with a prolonged latent phase are actually in false labor, and their contractions eventually abate spontaneously. The management of a prolonged latent phase involves either augmenting uterine activity with oxytocin or providing a sedative-induced period of maternal rest. Both are equally effective in advancing the labor to active phase dilatation. A very long latent phase may be a harbinger of other labor dysfunctions.

Disquiet concerning cesarean birth.

Cesarean birth has increased substantially in many parts of the world over recent decades and concerns have been raised about the propriety of this change in obstetric practice. Sometimes, a cesarean is necessary to preserve fetal and maternal health. But in balancing the risks of surgical intervention the implicit assumption has been that cesarean birth is an equivalent alternative to vaginal birth from the standpoint of the immediate and long-term health of the fetus and neonate. Increasingly, we realize this is not necessarily so. Delivery mode per se may influence short-term and abiding problems with homeostasis in offspring, quite independent of the indications for the delivery and other potentially confounding factors. The probability of developing various disorders, including respiratory compromise, obesity, immune dysfunction, and neurobehavioral disorders has been shown in some studies to be higher among individuals born by cesarean. Moreover, many of these adverse effects are not confined to the neonatal period and may develop over many years. Although the associations between delivery mode and long-term health are persuasive, their pathogenesis and causality remain uncertain. Full exploration and a clear understanding of these relationships is of great importance to the health of offspring.

Clinical evaluation of labor: an evidence- and experience-based approach.

During labor mother and fetus are evaluated at intervals to assess their well-being and determine how the labor is progressing. These assessments require skillful physical diagnosis and the ability to translate the acquired information into meaningful prognostic decision-making. We describe a coordinated approach to the assessment of labor. Graphing of serial measurements of cervical dilatation and fetal station creates "labor curves," which provide diagnostic and prognostic information. Based on these curves we recognize nine discrete labor abnormalities. Many may be related to insufficient or disordered contractile mechanisms. Several factors are strongly associated with development of labor disorders, including cephalopelvic disproportion, excess analgesia, fetal malpositions, intrauterine infection, and maternal obesity. Clinical cephalopelvimetry involves assessing pelvic traits and predicting their effects on labor. These observations must be integrated with information derived from the labor curves. Exogenous oxytocin is widely used. It has a high therapeutic index, but is easily misused. Oxytocin treatment should be restricted to situations in which its potential benefits clearly outweigh its risks. This requires there be a documented labor dysfunction or a legitimate medical reason to shorten the labor. Normal labor and delivery pose little risk to a healthy fetus; but dysfunctional labors, especially if stimulated excessively by oxytocin or terminated by complex operative vaginal delivery, have the potential for considerable harm. Conscientiously implemented, the approach to the evaluation of labor outlined in this review will result in a reasonable cesarean rate and minimize risks that may accrue from the labor and delivery process.

Performance of a Maternal Abdominal Surface Electrode System for Fetal Heart Rate and Uterine Contraction Monitoring from 34 to 37 Weeks.

OBJECTIVE: The objective of this study was to compare performance of a maternal surface electrode patch with ultrasound- and tocodynamometer-based monitoring to detect fetal heart rate and uterine contractility in late preterm labors. STUDY DESIGN: Thirty women between 340/7 and 366/7 weeks' gestation were monitored simultaneously with a Doppler/tocodynamometer system and a wireless fetal-maternal abdominal surface electrode system. Fetal and maternal heart rate and uterine contraction data from both systems were compared. Reliability was measured by the success rate and percent agreement. Deming regression and Bland-Altman analysis estimated the concordance between the systems. Uterine contractions were assessed by visual interpretation of monitor tracings. RESULTS: The success rate for the surface electrode system was 89.5% (95% confidence interval [CI], 85.7-93.3), and for ultrasound it was 88.4% (95% CI, 84.9-91.9; p = 0.73), with a percent agreement of 88.1% (95% CI, 84.2-92.8). Results were uninfluenced by the patients' body mass. The mean Deming slope was 1 and the y-intercept was -3.0 beats per minute (bpm). Bland-Altman plots also showed a close relationship between the methods, with limits of agreement less than 10 bpm. The percent agreement for maternal heart rate was 98.2% (95% CI, 97.4-98.8), and for uterine contraction detection it was 89.5% (95% CI, 85.5-93.4). CONCLUSION: Fetal heart rate and uterine contraction monitoring at 340/7 to 366/7 weeks using abdominal surface electrodes was not inferior to Doppler ultrasound/tocodynamometry for fetal-maternal assessment. REGISTRATION: clinicaltrials.gov/February 20, 2017/identifier NCT03057275. KEY POINTS: · Monitoring the preterm fetal heart rate with surface electrodes is feasible.. · Preterm contractions can be monitored with surface electrodes.. · The technique was noninferior to standard external monitors..

Guidelines for labor assessment: failure to progress?

The ongoing debate about what models of cervical dilatation and fetal descent should guide clinical decision-making has sown uncertainty among obstetric practitioners. We previously argued that the adoption of recently published labor assessment guidelines promoted by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine may have been premature. Before accepting any new clinical approaches as the standard of care, their underlying hypotheses should be thoroughly tested to ensure they are at least equivalent (or, preferably, superior) to existing management paradigms. Some of the apparent urgency to subscribe to new clinical tactics has been fueled by legitimate concerns about the rise in the cesarean delivery rate over the past several decades. A major contributor to this change in practice patterns is that more cesarean deliveries are being done for diagnoses that fall under the rubric of dystocia than ever before. As a consequence, traditional labor curves-fundamental for assessing labor progress-and the practice paradigms associated with them have received intense scrutiny as a possible contributor to this delivery trend. Moreover, the recent proposal of new labor curves and accompanying management guidelines has, understandably, fed the appetite to correct a perceived problem. However, the cesarean delivery rate rose most rapidly during decades when there was no major change in traditional labor curves or in the guidelines for their interpretation. Also, during the years since the new guidelines were first published, there has been no major fall in cesarean delivery frequency. This raises the question of whether there was truly a fundamental flaw in the traditional labor management paradigms or whether their proper interpretation and use had been somehow forgotten, ignored, or corrupted. More important, existing studies have shown that application of the new guidelines often (but not always) results in a modest fall in the cesarean delivery rate, but that this change may be accompanied by significant increases in maternal and neonatal morbidity. These results strongly suggest more caution in the adoption of the American College of Obstetricians and Gynecologists / Society for Maternal-Fetal Medicine labor assessment recommendations. They are based on a hypothesis that has yet to undergo thorough evaluation of its risks and benefits.

Relative accuracy of computerized intrapartum fetal heart rate pattern recognition by ultrasound and abdominal electrocardiogram detection.

INTRODUCTION: Noninvasive fetal heart rate monitoring using transabdominal fetal electrocardiographic detection is now commercially available and has been demonstrated to be an effective alternative to traditional Doppler ultrasonographic techniques. Our objective in this study was to compare the results of computerized identification of fetal heart rate patterns generated by ultrasound-based and transabdominal fetal electrocardiogram-based techniques with simultaneously obtained fetal scalp electrode-derived heart rate information. MATERIAL AND METHODS: We applied an objective computer-based analysis for recognition of fetal heart rate patterns (Monica Decision Support) to data obtained simultaneously from a direct fetal scalp electrode, Doppler ultrasound, and the abdominal-fetal electrocardiogram techniques. This allowed us to compare over 145 hours of fetal heart rate patterns generated by the external devices with those derived from the scalp electrode in 30 term singleton uncomplicated pregnancies during labor. The direct fetal scalp electrode is considered to be the most accurate and reliable technique used in current clinical practice, and was, therefore, used as the standard for comparison. The program quantified the baseline heart rate, long- and short-term variability. It indicated when an acceleration or deceleration was present and whether it was large or small. RESULTS: Ultrasound was associated with significantly greater deviations from the fetal scalp electrode results than the abdominal fetal electrocardiogram technique in recognizing the correct baseline heart rate, its variability, and the presence of small and large accelerations and small decelerations. For large decelerations the two external methods were each not significantly different from the scalp electrode results. CONCLUSIONS: Noninvasive fetal heart rate monitoring using maternal abdominal wall electrodes to detect fetal cardiac activity more reliably reproduced the computerized analysis of heart rate patterns derived from a direct fetal scalp electrode than did traditional ultrasound-based monitoring. Abdominal-fetal electrocardiogram should, therefore, be considered a primary option for externally monitored patients.

The assessment of labor: a brief history.

In the 1930s, investigators in the US, Germany and Switzerland made the first attempts to quantify the course of labor in a clinically meaningful way. They emphasized the rupture of membranes as a pivotal event governing labor progress. Attention was also placed on the total number of contractions as a guide to normality. Beginning in the 1950s, Friedman determined that changes in cervical dilatation and fetal station over time were the most useful parameters for the assessment of labor progress. He showed all normal labors had similar patterns of dilatation and descent, differing only in the durations and slopes of their component parts. These observations led to the formulation of criteria that elevated the assessment of labor from a rather arbitrary exercise to one guided by scientific objectivity. Researchers worldwide confirmed the basic nature of labor curves and validated their functionality. This system allows us to quantify the effects of parity, analgesia, maternal obesity, prior cesarean, maternal age, and fetal presentation and position on labor. It permits analysis of outcomes associated with labor aberrations, quantifies the effectiveness of treatments and assesses the need for cesarean delivery. Also, dysfunctional labor patterns serve as indicators of short- and long-term risks to offspring. We still lack the necessary translational research to link the physiologic manifestations of uterine contractility with changes in dilatation and descent. Recent efforts to interpret electrohysterographic patterns hold promise in this regard, as does preliminary exploration into the molecular basis of dysfunctional labor. For now, the clinician is best served by a system of labor assessment proposed more than 60 years ago and embellished upon in considerable detail since.

Changes in Sonographically Measured Inferior Vena Caval Diameter in Response to Fluid Loading in Term Pregnancy.

OBJECTIVES: The purpose of this study was to determine whether the inferior vena caval (IVC) diameter is influenced by intravascular volume changes in pregnancy. METHODS: A prospective observational study was done on 2 groups of normal term gravidas. In 24 patients, we measured the IVC diameter, blood pressure, and heart rate (HR) before and after a 1-L fluid infusion in preparation for regional anesthesia, after initiation of an epidural block, and within 24 hours postpartum. In a second group of 15 women, we measured the IVC diameter sequentially during a 1-L crystalloid infusion. RESULTS: In the first group, the mean baseline IVC diameter ± SD at end-inspiration was 1.45 ± 0.32 cm, which was 19% smaller than at end-expiration (1.73 ± 0.31 cm; P= .003). This respiratory cycle variation remained significant at each measurement epoch. The mean caval diameter at end-inspiration increased by 23% after the fluid bolus (P = .012). Hydration was not, however, accompanied by any significant change in the HR, mean arterial pressure, or collapsibility index of the inferior vena cava. With epidural anesthesia, the mean arterial pressure decreased from 88 ± 9 to 80 ± 7 mm Hg (P= .018), but the HR and collapsibility index remained unchanged. Postpartum values were not significantly different from their baseline measurements, except for the mean arterial pressure, which was lower by about 6 mm Hg (P = .042). In the second group, the IVC diameter at end-inspiration increased by 31% after the 1-L infusion, and there was a positive correlation between the volume infused and the IVC diameter (r= 0.67; P< .0001). CONCLUSIONS: Measurable variations in the IVC diameter occur in response to volume changes in normal term pregnancy and postpartum.

Perils of the new labor management guidelines.

Recent guidelines issued jointly by the American College of Obstetricians and Gynecologists and the Society for Maternal-Fetal Medicine for assessing labor progress differ substantially from those described initially by Friedman, which have guided clinical practice for decades. The guidelines are based on results obtained from new and untested methods of analyzing patterns of cervical dilatation and fetal descent. Before these new guidelines are adopted into clinical practice, the results obtained by these unconventional analytic approaches should be validated and shown to be superior, or at least equivalent, to currently accepted standards. The new guidelines indicate the patterns of labor originally described by Friedman are incorrect and, further, are inapplicable to modern obstetric practice. We contend that the original descriptions of normal and abnormal labor progress, which were based on direct clinical observations, accurately describe progress in dilatation and descent, and that the differences reported more recently are likely attributable to patient selection and the potential inaccuracy of very high-order polynomial curve-fitting methods. The clinical evaluation of labor is a process of serially estimating the likelihood of a safe vaginal delivery. Because many factors contribute to that likelihood, such as cranial molding, head position and attitude, and the bony architecture and capacity of the pelvis, graphic labor patterns should never be used in isolation. The new guidelines are based heavily on unvalidated notions of labor progress and ignore clinical parameters that should remain cornerstones of intrapartum decision-making.

Misguided guidelines for managing labor.

In a recent review we expressed concerns about new guidelines for the assessment and management of labor recommended jointly by the American Congress of Obstetricians and Gynecologists (ACOG) and the Society for Maternal-Fetal Medicine (SMFM). These guidelines are based heavily on a new concept of how cervical dilatation and fetal descent progress, derived from the work of Zhang et al. In their Viewpoint article they have addressed, but not allayed, the concerns we described in our review. We assert that the dilatation curve promulgated by Zhang et al cannot be reconciled with direct clinical observation. Even if they were correct, however, it still does not follow that the ACOG/SMFM guidelines should recommend replacing the coherent system of identifying and managing labor aberrations described by Friedman. That system is grounded in well-established clinical principles based on decades of use and the objectively documented association of some labor abnormalities with poor fetal and maternal outcomes. Recommendations for new clinical management protocols should require the demonstration of superior outcomes through extensive, preferably prospective, assessment. Using untested guidelines for the management of labor may adversely affect women and children. Even if those guidelines were to reduce the currently excessive cesarean delivery rate, the price of that benefit is likely to be a trade-off in harm to parturients and their offspring. The nature and degree of that harm needs to be documented before considering adoption of the guidelines.

Ebola virus screening during pregnancy in West Africa: unintended consequences.

OBJECTIVE: We hypothesized that predictive value of traditional Ebola virus disease (EVD) screening in West African pregnant women is low because febrile and hemorrhagic complications of pregnancy that can mimic EVD are common. METHODS: Proportions of various categories of pregnancy loss from a hypothetical cohort of West African gravidas were used to construct a Kaplan-Meier curve. The incidence rate of each category was determined by multiplying its proportion by the overall incidence rate, calculated from the inverse of the area under the curve. Incidence rates of Ebola-like illnesses during pregnancy were obtained by multiplying their percentages by the incidence rates of categories of loss with which they coincide. RESULTS: During pregnancy about 1.5% of suspected EVD cases would prove to have EVD. Most of the remaining 98.5% would have hemorrhagic and febrile complications of pregnancy. CONCLUSION: Current guidelines consider obstetrical interventions inappropriate in suspected EVD during pregnancy. However, because the overwhelming majority of cases suspected by screening do not have EVD and might benefit from obstetrical intervention, policy makers must consider whether the small risk to properly protected health care workers from the 1.5% with true EVD justifies withholding potentially life-saving care from the 98.5% who ultimately test negative for EVD.

Oxytocin utilization for labor induction in obese and lean women.

To determine if oxytocin dosage used for labor induction differed in obese and lean women, we analyzed records of patients who underwent term labor induction and delivered vaginally. Each of a cohort of 27 patients with a body mass index (BMI) >40 kg/m2 was matched with a patient with a BMI <28 kg/m2 for gestational age, for birth weight, and for cervical dilatation and fetal station at admission. The oxytocin dose administered during first stage labor was calculated for each patient. In addition to the matched characteristics, there was no difference between groups in parity, frequency of diabetes, epidural anesthesia use, or pharmacologic cervical ripening. Oxytocin utilization was significantly greater in obese women than in lean women. The maximum administration rate was 17.7±4.7 and 13.1±5.0 mU/min, respectively (P=0.001). Oxytocin administered per minute during the first stage of labor was greater in the obese group (11.6±4.8 vs. 8.6±4.1 mU/min; P=0.020). Neither active phase duration nor the maximum rate of dilatation differed significantly between the groups. That obese parturients required more oxytocin than lean women during the first stage of successful labor induction could not be explained by group differences in parity, birth weight, dysfunctional labor, pre-induction dilatation and station, or epidural use.

Influence of maternal body mass index on accuracy and reliability of external fetal monitoring techniques.

OBJECTIVE: To evaluate the performance of external electronic fetal heart rate and uterine contraction monitoring according to maternal body mass index. DESIGN: Secondary analysis of prospective equivalence study. SETTING: Three US urban teaching hospitals. SAMPLE: Seventy-four parturients with a normal term pregnancy. METHODS: The parent study assessed performance of two methods of external fetal heart rate monitoring (abdominal fetal electrocardiogram and Doppler ultrasound) and of uterine contraction monitoring (electrohystero-graphy and tocodynamometry) compared with internal monitoring with fetal scalp electrode and intrauterine pressure transducer. Reliability of external techniques was assessed by the success rate and positive percent agreement with internal methods. Bland-Altman analysis determined accuracy. We analyzed data from that study according to maternal body mass index. MAIN OUTCOME MEASURES: We assessed the relationship between body mass index and monitor performance with linear regression, using body mass index as the independent variable and measures of reliability and accuracy as dependent variables. RESULTS: There was no significant association between maternal body mass index and any measure of reliability or accuracy for abdominal fetal electrocardiogram. By contrast, the overall positive percent agreement for Doppler ultrasound declined (p = 0.042), and the root mean square error from the Bland-Altman analysis increased in the first stage (p = 0.029) with increasing body mass index. Uterine contraction recordings from electrohysterography and tocodynamometry showed no significant deterioration related to maternal body mass index. CONCLUSIONS: Accuracy and reliability of fetal heart rate monitoring using abdominal fetal electrocardiogram was unaffected by maternal obesity, whereas performance of ultrasound degraded directly with maternal size. Both electrohysterography and tocodynamometry were unperturbed by obesity.

Effect of maternal body mass index on oxytocin treatment for arrest of dilatation.

To determine whether the effectiveness of oxytocin treatment of arrest of dilatation differed in obese compared to lean women, we did a retrospective analysis of 118 subjects in spontaneous labor whose arrest of dilatation was treated with oxytocin. Cases were stratified by maternal body mass index (BMI): Group A, <25 kg/m2; Group B, 25.0-29.9 kg/m2; Group C, 30.0-34.9 kg/m2; and Group D, ≥ 35 kg/m². Groups were comparable in maternal age, parity, gestational age, birth weight, and the frequency of infection. Full dilatation was reached in about 90% of Group A and B, 72% of Group C, and 39% of Group D, the most obese women (P<0.001). The cesarean rate was directly related to maternal BMI, 11.4%, 22.9%, 34.3%, and 69.6% in Groups A through D, respectively (P<0.001). Significantly more oxytocin was used in group D than in the other groups during the first 3h of infusion in attempting to overcome the arrest (P=0.003). We conclude that oxytocin treatment of arrest of dilatation was less effective in obese than in lean women. This effect was most prominent in women with a BMI >35 kg/m2, who were, despite having received more oxytocin than those in the leaner groups, less than half as likely to attain full dilatation and more than twice as likely to deliver by cesarean.

Accuracy and reliability of fetal heart rate monitoring using maternal abdominal surface electrodes.

OBJECTIVE: Compare the accuracy and reliability of fetal heart rate identification from maternal abdominal fetal electrocardiogram signals (ECG) and Doppler ultrasound with a fetal scalp electrode. DESIGN: Prospective open method equivalence study. SETTING: Three urban teaching hospitals in the Northeast United States. SAMPLE: 75 women with normal pregnancies in labor at >37 weeks of gestation. METHODS: Three fetal heart rate detection methods were used simultaneously in 75 parturients. The fetal scalp electrode was the standard against which abdominal fetal ECG and ultrasound were judged. MAIN OUTCOME MEASURES: The positive percent agreement with the fetal scalp electrode indicated reliability. Bland-Altman analysis determined accuracy. The confusion rate indicated how frequently the devices tracked the maternal heart rate. RESULTS: Positive percent agreement was 81.7 and 73% for the abdominal fetal ECG and ultrasound, respectively (p = 0.002). The abdominal fetal ECG had a lower root mean square error than ultrasound (5.2 vs. 10.6 bpm, p < 0.001). The confusion rate for ultrasound was 20-fold higher than for abdominal ECG (8.9 vs. 0.4%, respectively, p < 0.001). CONCLUSION: Compared with the fetal scalp electrode, fetal heart rate detection using abdominal fetal ECG was more reliable and accurate than ultrasound, and abdominal fetal ECG was less likely than ultrasound to display the maternal heart rate in place of the fetal heart rate.