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. 2021 Feb;100(2):252-262.
doi: 10.1111/aogs.14007. Epub 2020 Oct 15.

Intrapartum zigzag pattern of fetal heart rate is an early sign of fetal hypoxia: A large obstetric retrospective cohort study

Mikko Tarvonen  1 , Petteri Hovi  2   3 , Susanna Sainio  4 , Piia Vuorela  5 , Sture Andersson  3 , Kari Teramo  1
Affiliations

Intrapartum zigzag pattern of fetal heart rate is an early sign of fetal hypoxia: A large obstetric retrospective cohort study

Mikko Tarvonen et al. Acta Obstet Gynecol Scand. 2021 Feb.

Abstract

Introduction: The aim of the present study was to identify possible associations of fetal heart rate (FHR) patterns during the last 2 hours of labor with fetal asphyxia expressed by umbilical artery acidemia at birth and with neonatal complications in a large obstetric cohort.

Material and methods: Cardiotocographic recordings from 4988 singleton term childbirths over 1 year were evaluated retrospectively and blinded to the pregnancy and neonatal outcomes in a university teaching hospital in Helsinki, Finland. Umbilical artery pH, base excess and pO2 , low Apgar scores at 5 minutes, need for intubation and resuscitation, early neonatal hypoglycemia, and neonatal encephalopathy were used as outcome variables. According to the severity of the neonatal complications at birth, the cohort was divided into three groups: no complications (Group 1), moderate complications (Group 2) and severe complications (Group 3).

Results: Of the 4988 deliveries, the ZigZag pattern (FHR baseline amplitude changes of >25 bpm with a duration of 2-30 minutes) occurred in 11.7%, late decelerations in 41.0%, bradycardia episodes in 52.9%, reduced variability in 36.7%, tachycardia episodes in 13.9% and uterine tachysystole in 4.6%. No case of saltatory pattern (baseline amplitude changes of >25 bpm with a duration of >30 minutes) was observed. The presence of the ZigZag pattern or late decelerations, or both, was associated with cord blood acidemia (odds ratio [OR] 3.3, 95% confidence interval [CI] 2.3-4.7) and severe neonatal complications (Group 3) (OR 3.3, 95% CI 2.4-4.9). In contrast, no significant associations existed between the other FHR patterns and severe neonatal complications. ZigZag pattern preceded late decelerations in 88.7% of the cases. A normal FHR preceded the ZigZag pattern in 90.4% of the cases, whereas after ZigZag episodes, a normal FHR pattern was observed in only 0.9%.

Conclusions: ZigZag pattern and late decelerations during the last 2 hours of labor are significantly associated with cord blood acidemia at birth and neonatal complications. The ZigZag pattern precedes late decelerations, and the fact that normal FHR pattern precedes the ZigZag pattern in the majority of the cases suggests that the ZigZag pattern is an early sign of fetal hypoxia, which emphasizes its clinical importance.

Keywords: ZigZag pattern; cardiotocography; fetal heart rate; fetal hypoxia; fetal monitoring; neonatal complications; saltatory pattern.

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Conflict of interest statement

None.

Figures

Figure 1
Figure 1
Flow chart of the study participants and grouping of the newborn infants according to the severity of complications. BE, base excess; CTG, cardiotocography; P‐glucose, plasma glucose; UA, umbilical artery
Figure 2
Figure 2
Intrapartum CTG recording of a 35‐year‐old nullipara at 42+1 weeks' gestation. At left, normal baseline fetal heart rate (FHR) with normal variability and accelerations followed by a 10‐minute ZigZag pattern. The ZigZag episode is followed by repetitive late decelerations and decreased FHR baseline. Normal frequency of uterine contractions (2‐3 contractions in 10‐minute periods). ZigZag pattern occurred 105 min before a male fetus was spontaneously born in vertex position. Umbilical cord blood gas analysis showed acidemia: umbilical artery (UA) pH 7.09, UA base excess −12.9 mmol/L, UA pO2 1.9 kPa. Apgar scores of 7 and 7 at 1 and 5 min, respectively. FHR was recorded via scalp electrode. Paper speed 1 cm/min
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References

    1. Nelson KB, Dambrosia JM, Ting TY, Grether JK. Uncertain value of electronic fetal monitoring in predicting cerebral palsy. N Engl J Med. 1996;334:613‐618. - PubMed
    1. Low JA, Pickersgill H, Killen H, Derrick EJ. The prediction and prevention of intrapartum fetal asphyxia in term pregnancies. Am J Obstet Gynecol. 2001;184:724‐730. - PubMed
    1. Steer PJ, Kovar I, McKenzie C, Griffin M, Linsell L. Computerised analysis of intrapartum fetal heart rate patterns and adverse outcomes in the INFANT trial. BJOG. 2019;126:1354‐1361. - PubMed
    1. Parer JT, Ikeda T. A framework for standardized management of intrapartum fetal heart rate patterns. Am J Obstet Gynecol. 2007;197:26.e1‐26.e266. - PubMed
    1. Nelson KB, Blair E. Prenatal factors in singletons with cerebral palsy born at or near term. N Engl J Med. 2015;373:946‐953. - PubMed

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