Intrapartum Fetal ECG ST-Segment Analysis - Intrapartum Fetal ECG ST-Segment Analysis


The goal of the trial was to compare the efficacy of using fetal electrocardiography (ECG) ST-segment analysis as an adjunct to conventional intrapartum electronic fetal heart-rate monitoring on perinatal outcomes.

Contribution to the Literature: The trial showed that routine ST-segment monitoring and analysis as an adjunct to routine fetal monitoring is not associated with superior maternal or neonatal outcomes.

Study Design

Eligible pregnant women who were attempting vaginal delivery were randomized to continuous fetal ECG ST-segment monitoring (n = 5,532) or routine care (n = 5,576). A specific treatment algorithm existed throughout labor and delivery.

  • Total number of enrollees: 11,108
  • Mean patient age: 27.3 years
  • Percentage female: 100%
  • Week of pregnancy: 39.4
  • Caucasian: 59%, Black: 24%
  • Spontaneous labor: 41%

Inclusion criteria:

  • Singleton fetus
  • ≥36 weeks of gestation
  • Vaginal delivery
  • Cervical dilation of 2-7 cm

Exclusion criteria:

  • Noncephalic presentation
  • Planned cesarean delivery
  • Need for immediate delivery
  • Absent fetal heart-rate variability (amplitude range undetectable) or a sinusoidal pattern
  • Minimal fetal heart-rate variability in the 20 minutes before randomization
  • Other fetal or maternal conditions that would preclude a trial of labor or the placement of a scalp electrode
  • Inability to obtain or maintain an adequate fetal ECG signal after three attempts at electrode placement or if an ST-segment event occurred during the attempts to obtain an adequate signal

Principal Findings:

The primary outcome, intrapartum fetal death, neonatal death, an Apgar score of ≤3 at 5 minutes, neonatal seizure, an umbilical-artery blood pH of ≤7.05 with a base deficit of ≥12 mmol/L, intubation for ventilation at delivery, or neonatal encephalopathy for ST-segment monitoring vs. routine care: 0.94% vs. 0.72%, hazard ratio 1.31, 95% confidence interval 0.87-1.98, p = 0.20. Intrapartum fetal death: 0%; neonatal death: 0.05% vs. 0.02%, p = 0.37, intubation: 0.76% vs. 0.48%, p = 0.07.

Secondary outcomes:

  • Spontaneous delivery: 77.2% vs. 78.0%
  • Cesarean: 16.9% vs. 16.2%, p = 0.17
  • Fetal indication for C-section: 30.7% vs. 33.1%, p = 0.45
  • Median duration of labor: 3.8 vs. 3.9 hours, p = 0.32
  • Median Apgar score: 9 vs. 9; p = 0.54


The results of this trial indicate that routine ST-segment monitoring and analysis as an adjunct to routine fetal monitoring is not associated with superior maternal or neonatal outcomes. This is one of the largest trials on the topic. Interest in ST-segment analysis during delivery comes from studies showing that it provided useful information regarding fetal acidemia and myocardial metabolism.


Belfort MA, Saade GR, Thom E, et al., on behalf of the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal–Fetal Medicine Units Network. A Randomized Trial of Intrapartum Fetal ECG ST-Segment Analysis. N Engl J Med 2015;373:632-41.

Clinical Topics: Congenital Heart Disease and Pediatric Cardiology, Congenital Heart Disease

Keywords: Apgar Score, Delivery, Obstetric, Electrocardiography, Heart Defects, Congenital, Fetal Heart, Fetal Monitoring, Infant, Newborn, Intubation, Labor, Obstetric, Pregnancy, Seizures

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