Fetal Heart Rate Monitoring
NICHD definitions, categories and intrauterine resuscitation
Baseline and variability
| Baseline | 110–160 bpm (average over 10 min) |
| Tachycardia | >160 for ≥10 min: maternal fever or infection, maternal tachycardia, terbutaline, fetal hypoxia, anemia |
| Bradycardia | <110 for ≥10 min: hypoxia, cord prolapse, maternal hypotension, uterine rupture, beta blockers |
| Variability | Absent (undetectable) · minimal (≤5) · moderate (6–25) = reassuring · marked (>25) |
Minimal variability can be fetal sleep (up to ~40 min), opioids or magnesium, or hypoxia.
Accelerations
A good sign: the fetus is well-oxygenated (not acidotic).
- ≥32 weeks: rise ≥15 bpm lasting ≥15 sec.
- <32 weeks: rise ≥10 bpm lasting ≥10 sec.
Sinusoidal pattern
Smooth, wave-like, no variability: severe fetal anemia (e.g., Rh disease, fetal bleeding). Category III.
Decelerations
| Type | Looks like | Cause | Action |
|---|---|---|---|
| Early | Gradual; mirrors the contraction (lowest point at the peak) | Head compression | None: normal |
| Variable | Abrupt drop and return; V, U or W shape; any timing | Cord compression | Reposition; if recurrent: stop oxytocin, check for prolapse, amnioinfusion if ordered |
| Late | Gradual; the lowest point comes after the peak of the contraction, and it recovers after the contraction ends | Uteroplacental insufficiency | Intrauterine resuscitation (below); notify |
| Prolonged | Drop ≥15 bpm lasting 2–10 min | Many (cord, hypotension, tachysystole) | Resuscitation; notify; prepare for birth |
Memory hook: VEAL CHOP
| Variable | Cord compression |
| Early | Head compression |
| Accelerations | OK (oxygenated) |
| Late | Placental insufficiency |
Three categories
- Category I (normal): baseline 110–160, moderate variability, no late or variable decels (early decels and accels may be present).
- Category II (indeterminate): everything that is not I or III. Evaluate, resuscitate, re-evaluate.
- Category III (abnormal): absent variability with recurrent lates, recurrent variables, or bradycardia; or sinusoidal. Prepare for rapid delivery.
Intrauterine resuscitation (late decels, recurrent variables, Category II–III)
- Stop oxytocin.
- Reposition (left or right lateral, hands-and-knees).
- IV fluid bolus; correct maternal hypotension (epidural).
- Treat tachysystole (terbutaline if ordered).
- Vaginal exam if cord prolapse possible.
- Notify the provider; document actions and response.
- Prepare for expedited birth if it doesn't resolve.
- Oxygen: give for maternal hypoxia. Updated Routine high-flow O₂ by non-rebreather for fetal benefit is not supported by current evidence.