Is a fetal heart rate of 114‑120 bpm at 36 weeks gestation considered normal and what is the appropriate management?

Fetal Heart Rate of 114-120 bpm at 36 Weeks: Assessment and Management

A fetal heart rate of 114-120 bpm at 36 weeks gestation falls at the lower end of the normal range and warrants close monitoring, but does not require immediate intervention if other reassuring features are present.

Understanding the Normal Range

The definition of normal baseline fetal heart rate varies slightly across guidelines, but converges around 110-160 bpm:

• The American Academy of Family Physicians defines normal baseline FHR as 110-160 bpm 1
• Research suggests that 120-160 bpm may represent the optimal "normal range" based on large-scale computerized analysis of over 78,000 tracings 2
• FHR decreases slightly as gestation advances, making rates at the lower end of normal more common in late pregnancy 2
• At 40 weeks gestation, the 90th centile of FHR has been consistently found around 150 bpm, indicating progressive decline with advancing gestation 3

Your patient's FHR of 114-120 bpm is technically within the accepted normal range of 110-160 bpm, though it sits at the lower boundary 1, 4.

Critical Assessment Required

The key is not the baseline rate alone, but the complete fetal heart rate pattern. You must immediately assess:

Essential Components to Evaluate

• Baseline variability: Moderate variability (6-25 bpm) is the most reassuring feature and predicts absence of fetal acidemia 1, 5
• Presence of accelerations: Accelerations indicate fetal well-being and predict absence of acidemia 1, 6
• Absence of decelerations: Particularly late or variable decelerations, which when combined with absent variability indicate fetal compromise 1, 6
• Maternal factors: Check for fever, infection, medications, or hyperthyroidism that could affect FHR 5

NICHD Category Classification

If the FHR of 114-120 bpm has moderate variability and no concerning decelerations, this represents a Category I (normal) tracing 1:

• Continue routine monitoring
• No intervention required
• This is reassuring despite the lower baseline 1

If bradycardia (defined as <110 bpm) develops or if absent variability is present, this becomes Category II (indeterminate) 1:

• Implement general measures: left lateral positioning, oxygen administration, IV fluid bolus 5, 6
• Perform vaginal examination to rule out cord prolapse or rapid descent 5
• Check maternal vital signs 5
• Consider expedited delivery if abnormalities persist 1

If absent baseline variability occurs with recurrent decelerations or true bradycardia (<110 bpm), this is Category III (abnormal) 1:

• Requires immediate intervention and expedited delivery 1, 6

Specific Management at 36 Weeks

At 36 weeks gestation with this FHR pattern:

• Obtain continuous electronic fetal monitoring to properly classify the complete tracing 5
• If the pattern is reassuring (moderate variability, no decelerations), continue standard antenatal surveillance 1
• Schedule follow-up monitoring within 3-7 days to ensure the pattern remains stable 5
• Consider delivery at 37 weeks if the pattern becomes persistently concerning without clear reversible cause 5

Common Pitfalls to Avoid

• Do not focus solely on the baseline rate—the presence of moderate variability is far more predictive of fetal well-being than the absolute baseline number 1, 5
• Fetal sleep cycles (20-40 minutes) can temporarily decrease variability—wait for the fetus to wake before concluding variability is truly absent 5
• Medications (analgesics, anesthetics, magnesium sulfate) can decrease variability without indicating fetal compromise 5
• Distinguish between true bradycardia (<110 bpm) and a low-normal baseline (110-120 bpm)—management differs significantly 1

When to Escalate Care

Expedite delivery if:

• The baseline drops below 110 bpm persistently 1
• Absent variability develops with recurrent late or variable decelerations 1, 6
• The pattern progresses to Category III despite resuscitative measures 1, 5

In summary: A rate of 114-120 bpm with moderate variability and no decelerations is reassuring and requires only continued monitoring; however, absent variability or concerning decelerations at this baseline rate would necessitate immediate intervention.