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DOI: 10.1055/s-0041-1735285
Intrapartum Fetal Electrocardiogram in Small- and Large-for-Gestational Age Fetuses
Funding This work is supported by grants HD34208, HD53097, HD40545, HD40560, HD27869, HD40485, HD40512, HD27915, HD40544, HD40500, HD68282, HD68268, HD27917, HD21410, and U10 HD36801 from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) and by funding from Neoventa Medical. Comments and views expressed in this article are those of the authors and do not necessarily represent views of the NICHD. Neoventa Medical did not participate in the monitoring of the study; data collection, management, or analysis; or manuscript preparation.

Abstract
Objective This study aimed to evaluate whether intrapartum fetal electrocardiogram (ECG) tracings with ST-elevation or depression occur more frequently in each stage of labor in small-for-gestational age (SGA) or large-for-gestational age (LGA), as compared with appropriate-for-gestational age (AGA) fetuses.
Study Design We conducted a secondary analysis of a large, multicenter trial in which laboring patients underwent fetal ECG waveform-analysis. We excluded participants with diabetes mellitus and major fetal anomalies. Birth weight was categorized as SGA (<10th percentile), LGA (>90th percentile), or AGA (10–90th percentile) by using a gender and race/ethnicity specific nomogram. In adjusted analyses, the frequency of ECG tracings with ST-depression or ST-elevation without depression was compared according to birthweight categories and labor stage.
Results Our study included 4,971 laboring patients in the first stage and 4,074 in the second stage. During the first stage of labor, there were no differences in the frequency of ST-depression in SGA fetuses compared with AGA fetuses (6.7 vs. 5.5%; adjusted odds ratio [aOR]: 1.41, 95% confidence interval [CI]: 0.93–2.13), or in ST-elevation without depression (35.8 vs. 34.1%; aOR: 1.17, 95% CI: 0.94–1.46). During the second stage, there were no differences in the frequency of ST-depression in SGA fetuses compared with AGA fetuses (1.6 vs. 2.0%; aOR: 0.69, 95% CI: 0.27–1.73), or in ST-elevation without depression (16.2 vs. 18.1%; aOR: 0.90, 95% CI: 0.67–1.22). During the first stage of labor, there were no differences in the frequency of ST-depression in LGA fetuses compared with AGA fetuses (6.3 vs. 5.5%; aOR: 0.97, 95% CI: 0.60–1.57), or in ST-elevation without depression (33.1 vs. 34.1%; aOR: 0.80, 95% CI: 0.62–1.03); during the second stage of labor, the frequency of ST-depression in LGA compared with AGA fetuses (2.5 vs. 2.0%, aOR: 1.36, 95% CI: 0.61–3.03), and in ST-elevation without depression (15.5 vs. 18.1%; aOR: 0.83, 95% CI: 0.58–1.18) were similar as well.
Conclusion The frequency of intrapartum fetal ECG tracings with ST-events is similar among SGA, AGA, and LGA fetuses.
Key Points
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SGA and LGA neonates are at increased risk of cardiac dysfunction.
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Fetal ECG has been used to evaluate fetal response to hypoxia.
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Fetal ST-elevation and ST-depression occur during hypoxia.
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Frequency of intrapartum ST-events is similar among SGA, AGA and LGA fetuses.
Keywords
fetal ECG - small-for-gestational age - fetal growth restriction - large-for-gestational age - ST-segment analysis - ST-events* See [Supplementary Material] for a list of other members of the NICHD MFMU Network.
Publication History
Received: 20 February 2021
Accepted: 23 July 2021
Article published online:
31 August 2021
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