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Antepartum and intrapartum fetal monitoring

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ACOG antepartum fetal surveillance intrapartum fetal heart rate monitoring guidance

Antepartum and intrapartum fetal monitoring covers assessment of fetal well-being before labor and during labor, with the aim of detecting evolving hypoxemia or acidemia early enough to guide safe management.

Topic map

  1. Principles of fetal oxygenation and fetal compromise
  2. Antepartum fetal surveillance
    • Maternal fetal-movement assessment
    • Nonstress test (NST)
    • Contraction stress test (CST)
    • Biophysical profile (BPP)
    • Modified BPP
    • Ultrasound growth assessment, amniotic-fluid assessment, Doppler velocimetry
    • Indications, timing, frequency, interpretation, and limitations
  3. Intrapartum monitoring methods
    • Intermittent auscultation
    • External electronic fetal monitoring / cardiotocography (CTG)
    • Internal fetal scalp electrode and intrauterine pressure catheter
  4. CTG interpretation
    • Baseline FHR, variability, accelerations
    • Early, variable, late, and prolonged decelerations
    • Sinusoidal pattern
    • Three-tier Category I, II, and III classification
  5. Management of nonreassuring FHR patterns
    • Immediate assessment and intrauterine resuscitative measures
    • Evaluation for reversible causes
    • Indications for expedited operative delivery
  6. Special situations
    • Fetal growth restriction, oligohydramnios, hypertensive disease, diabetes, post-term pregnancy, decreased fetal movement, meconium, induction/augmentation, and trial of labor after cesarean.

High-level overview

Antepartum surveillance is selectively used in pregnancies with a higher risk of stillbirth, such as fetal growth restriction or maternal diabetes/hypertension. It combines fetal heart-rate reactivity, fetal movement, amniotic-fluid volume, biophysical activity, growth, and Doppler findings. A normal test lowers short-term risk but does not guarantee fetal well-being, so findings must be interpreted with gestational age and the clinical scenario. ACOG reports approximate false-negative rates of 1.9 per 1,000 for NST, 0.3 per 1,000 for CST, and 0.8 per 1,000 for BPP or modified BPP in its outpatient surveillance guidance.
Intrapartum monitoring uses either intermittent auscultation in appropriately selected low-risk labor or continuous CTG when risks or clinical circumstances warrant closer monitoring. CTG interpretation focuses on the baseline heart rate, variability, accelerations, decelerations, and uterine activity. The current ACOG intrapartum guideline uses standardized FHR terminology and a three-tier classification system. Category I is reassuring; Category III is abnormal and requires prompt evaluation and action; Category II is indeterminate and requires context-specific surveillance and management.
Recent evidence should not be interpreted as a reason for indiscriminate monitoring: a 2024 systematic review found continuous electronic monitoring can materially affect women’s experience of labor (PMID: 38754249). Monitoring must therefore have a clear indication and lead to a planned, proportionate response.
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