Fetal Heart Rate (FHR) Decelerations

Early Decelerations

• Timing: Gradual decrease and return to baseline FHR mirroring uterine contractions.
  • The lowest point is the same as the peak uterine contraction.
• Nadir (lowest point): Occurs at the same time as the peak of the contraction.
• Cause: Fetal head compression (vagal stimulation).
• Clinical significance: Benign; typically seen in active labor.
• Management: No intervention needed.

Variable Decelerations

• Timing: Abrupt decrease in FHR; not consistent in relation to contractions.
• Shape: Often V-shaped or U-shaped; rapid drop and return.
  • A decrease of 15 beats per minute or more below baseline, lasting 15 seconds or more but less than two minutes
• Cause: Umbilical cord compression (often due to oligohydramnios or nuchal cord).
• Clinical significance: Common, usually transient and tolerable, but repetitive or severe ones may indicate fetal compromise.
• Management:
  • Change maternal position (e.g., left lateral)
  • Amnioinfusion if due to oligohydramnios
  • Oxygen, IV fluids, stop oxytocin
  • Consider delivery if persistent or worsening

Late Decelerations

• Timing: Gradual decrease in FHR that begins after the contraction starts and returns to baseline after the contraction ends.
• Cause: Uteroplacental insufficiency → fetal hypoxia.
• Clinical significance: Concerning – may indicate fetal distress.
• Associated factors:
  • Maternal hypotension
  • Preeclampsia
  • Post-term pregnancy
  • Placental abruption
• Management:
  • Left lateral position
  • Oxygen, IV fluids
  • Stop oxytocin
  • Treat underlying cause
  • Prepare for delivery if persistent

Prolonged Decelerations

• Timing: FHR decrease of ≥15 bpm lasting 2–10 minutes.
• Cause: Multiple - cord prolapse, maternal hypotension, uterine rupture, seizure, etc.
• Clinical significance: Emergent – reflects acute hypoxia.
• Management:
  • Immediate evaluation
  • Correct reversible causes
  • Emergency delivery if no improvement

VEAL CHOP