Characteristics of fetal and maternal heart rate tracings during labor: A prospective observational study

Sporadic accelerations during labor strongly indicate normal pH, whereas periodic accelerations do not: a case-control study

PURPOSE

To determine the association between the occurrence of sporadic and periodic fetal heart rate accelerations during labor and acidemia at birth.

MATERIALS AND METHODS

This is a case-control study of fetal heart rate patterns from 364 neonates with acidemia at birth (cord blood pH <7.05 at vaginal birth, or pH <7.10 at birth after first stage cesarean delivery) and 731 controls with pH ≥7.15. The last 30-60 min of the cardiotocographic traces before birth from the neonates born with acidemia and from the corresponding stage in labor for the controls were scrutinized. Odds ratios (OR) with 95% confidence interval for acidemia at birth were determined.

RESULTS

During the first stage, ≥2 sporadic accelerations were present in 16% of cases and 78% of controls; OR for acidemia (compared to 0-1 accelerations) 0.05 (0.02-0.10). In the second stage, the corresponding rates were 13% and 60%, OR 0.09 (0.06-0.14). Isolated periodic accelerations were infrequent. A weak negative association between ≥2 periodic accelerations and acidemia (compared with 0-1 accelerations) was found in the second stage, OR 0.51 (0.30-0.86), but was not significant in the first stage, OR 0.24 (0.04-1.4). Even among fetuses with normal fetal heart rate variability (5-25 beats per minute) the occurrence of less than two sporadic accelerations was associated with an increased risk of acidemia, OR 10.3 (7.2-14.8).

CONCLUSIONS

Sporadic accelerations indicate a very low probability of acidosis but are absent in 40% of fetuses with normal pH during a 30-60 min second-stage recording.

Technical Update No. 429: Maternal Heart Rate Artefact During Intrapartum Fetal Health Surveillance

OBJECTIVE

To improve perinatal outcomes and minimize provider error by increasing awareness of strategies to detect intrapartum maternal heart rate artefact and to respond when such artefact is suspected.

TARGET POPULATION

All pregnant patients during labour.

OPTIONS

Maternal heart rate artefact may be detected based on clinical features or through technology. Suspected maternal heart rate artefact may be assessed by applying a fetal scalp electrode (preferred) or through external fetal monitoring, augmented by point-of-care sonography (alternative).

OUTCOMES

Unrecognized intrapartum maternal heart rate artefact increases the risk that abnormal/atypical fetal heart rate patterns will go undetected and, hence, the risk of adverse perinatal outcomes.

BENEFITS, HARMS, AND COSTS

Unrecognized maternal heart rate artefact can lead to adverse perinatal outcomes (hypoxic-ischemic encephalopathy, fetal death, and neonatal death) and adverse maternal outcomes (unnecessary cesarean delivery or operative vaginal delivery). Timely recognition of such artefact may avoid these adverse outcomes. The costs of early recognition of maternal heart rate artefact are relatively small: increased use of fetal scalp electrodes and point-of-care sonography, as well as additional assessments by the health care provider. The cost savings are significant, as a result of lower risk of adverse perinatal outcomes. Potential harms are false-positive diagnoses of maternal heart rate artefact, expediting delivery unnecessarily when the fetal status cannot be reliably determined but is normal, and the rare complications associated with increased use of fetal scalp electrodes.

EVIDENCE

Two PubMed searches were completed. The first was for articles published between January 1, 1970, and November 25, 2021, using the medical subject headings (MeSH) "fetal monitoring" and "artifacts" (38 articles). The second was for articles published during the same period using the MeSH "fetal monitoring" and "maternal heart rate" (841 articles).

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix A (Tables A1 for definitions and A2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

All health care providers involved in obstetrical care.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Mise à jour technique no 429 : Artéfact de la fréquence cardiaque maternelle pendant la surveillance du bien-être fœtal per partum

OBJECTIF

Améliorer les issues périnatales et réduire au minimum le risque d'erreurs chez les fournisseurs en améliorant leurs connaissances sur les stratégies de détection des artéfacts de la fréquence cardiaque maternelle per partum et sur les modes d'intervention lorsque de tels artéfacts sont soupçonnés.

POPULATION CIBLE

Toutes les parturientes.

OPTIONS

L'artéfact de la fréquence cardiaque maternelle peut être détecté à l'aide de caractéristiques cliniques ou de la technologie. On peut évaluer l'artéfact de la fréquence cardiaque maternelle soupçonné en posant une électrode de cuir chevelu fœtal (option à privilégier) ou en recourant à la surveillance fœtale externe optimisée par l'échographie au chevet (solution de rechange). RéSULTATS: Les artéfacts de la fréquence cardiaque maternelle per partum non détectés augmentent le risque que des rythmes anormaux ou atypiques de la fréquence cardiaque fœtale passent inaperçus, ce qui augmente le risque d'issues périnatales défavorables. BéNéFICES, RISQUES ET COûTS: L'artéfact de la fréquence cardiaque maternelle non détecté peut entraîner de graves issues périnatales défavorables (encéphalopathie hypoxo-ischémique, mort fœtale et mort néonatale) et des issues maternelles défavorables (césarienne injustifiée ou accouchement assisté). Ces issues peuvent être évitées par la détection rapide d'un tel artéfact. Le coût de la détection précoce des artéfacts de fréquence cardiaque maternelle est relativement faible (utilisation accrue des électrodes de cuir chevelu fœtal et de l'échographie au chevet avec évaluations supplémentaires par le fournisseur de soins). La réduction des événements périnataux défavorables engendre des économies considérables. Les risques sont : faux positifs d'artéfact de la fréquence cardiaque maternelle; accélération inutile de l'accouchement lorsque l'état du fœtus est normal, mais qu'on ne peut le déterminer de façon fiable; et les rares complications associées à l'utilisation accrue des électrodes de cuir chevelu fœtal. DONNéES PROBANTES: Deux recherches ont été effectuées dans PubMed. La première a été réalisée pour répertorier les articles publiés entre le 1^er janvier 1970 et le 25 novembre 2021 à partir des termes MeSH fetal monitoring et artifacts (38 articles); la deuxième, pour répertorier les articles publiés au cours de la même période à partir des termes MeSH fetal monitoring et maternal heart rate (841 articles). MéTHODES DE VALIDATION: Les auteurs ont évalué la qualité des données probantes et la force des recommandations en utilisant le cadre méthodologique GRADE (Grading of Recommendations, Assessment, Development, and Evaluation). Voir l'annexe A en ligne (tableau A1 pour les définitions et tableau A2 pour l'interprétation des recommandations fortes et conditionnelles [faibles]). PROFESSIONNELS CONCERNéS: Tous les fournisseurs de soins obstétricaux. DÉCLARATIONS SOMMAIRES: RECOMMANDATIONS.

Fetal Heart Rate Extraction Based on Wavelet Transform to Prevent Fetal Distress In Utero

In order to improve the effective extraction of fetal heart rate and prevent fetal distress in utero, a study of fetal heart rate feature extraction based on wavelet transform to prevent fetal distress in utero was proposed. This paper adopts a fetal heart rate detection method based on the maximum value of the binary wavelet transform modulus. The method is simulated by the Doppler fetal heart signal obtained from the clinic. Compared with the original curve, the transformed curve can roughly see the change rule of the original signal and identify the peak point of the signal, but due to the large disturbance of the peak point, the influence on the computer processing is also great. The periodicity of the transformed signal is greatly enhanced, making it easier to deal with the computation. A total of 300 pregnant women with full-term fetal heart monitoring from January 2018 to January 2020 were selected as the research subjects and divided into the observation group and the control group. The observation group consisted of 100 patients with abnormal fetal heart monitoring, and the control group consisted of 200 patients with normal fetal heart monitoring. The uterine contractions and fetal heart rate were recorded, and the incidence of fetal distress, cesarean section, neonatal asphyxia, and amniotic fluid and fecal contamination were observed. The incidence of fetal distress, cesarean section, neonatal asphyxia, and amniotic fluid fecal stain in the observation group were significantly higher than those in the control group. Fetal heart monitoring can accurately judge the situation of the fetus in pregnant women and timely diagnose the abnormal fetal heart rate, which has a better effect on the prognosis of perinatal infants and can reduce their mortality. It can effectively solve the problems existing in the autocorrelation algorithm and extract the fetal heart rate more accurately. It is an effective improved scheme of fetal heart rate extraction. It is very helpful in preventing fetal distress in utero.