Fetal Heart Rate Patterns

Normal Fetal Heart Rate Patterns

Baseline Heart Rate

• Normal Range: 110-160 beats per minute

Accelerations

• Definition: An increase by at least 15 beats per minute from the baseline, sustained for at least 15 seconds
• Significance: Indicative of adequate oxygenation and fetal well-being
• Causes: Fetal movements, vaginal exams

Early Decelerations

• Definition: Deceleration that mirrors contractions (peak of contraction matches the lowest point of deceleration)
• Significance: Usually benign and caused by fetal head compression

Variability

• Definition: Fluctuations in the fetal heart rate by 6 to 25 beats per minute around the baseline
• Significance: Indicates a healthy fetal nervous system
• Types: Absent, minimal, moderate, marked
• Preferred Type: Moderate variability

Abnormal Fetal Heart Rate Patterns

Fetal Bradycardia

• Definition: Baseline heart rate less than 110 beats per minute, sustained for 10 minutes or more
• Causes: Prolonged cord compression, umbilical cord prolapse, anesthetic meds, fetal heart abnormalities
• Interventions: Side-lying position, oxygen, IV fluids, notify provider, stay at bedside

Fetal Tachycardia

• Definition: Baseline heart rate more than 160 beats per minute, sustained for 10 minutes or more
• Causes: Maternal fever, infection, fetal hypoxia, maternal hypothyroidism, cocaine use
• Interventions: Treat underlying cause (e.g., antipyretics for fever), IV fluids, oxygen
• Note: Accompanied by decreased variability indicates severe fetal distress

Late Decelerations

• Definition: Deceleration offset from contractions (drops after the peak of contraction)
• Causes: Uteroplacental insufficiency
• Interventions: LIONS (Left-lying position, IV fluids, Oxygen, Notify provider, Stop oxytocin), prep for surgery if unresolved

Variable Decelerations

• Definition: Sharp, sudden drops and quick recovery in fetal heart rate
• Causes: Umbilical cord compression
• Interventions: Trendelenburg or knee-chest position, oxygen, discontinue oxytocin, notify provider, possible amnioinfusion for oligohydramnios

Mnemonics

VEAL CHOP

• Variable - Cord compression
• Early - Head compression
• Accelerations - Okay
• Late - Placental insufficiency

Quiz Questions

1. What is the normal baseline for fetal heart rate?
2. For which fetal heart rate pattern would you place the mom in Trendelenburg or knee-chest position?
3. What does moderate variability in the fetal heart rate indicate?
4. What is the cause of late decelerations?