Fetal Heart Tones: What Every Nursing Student Must Know for the NCLEX

By The Student Nursing Essentials

Monitoring fetal heart tones (FHTs) is one of the most important skills in obstetric nursing - and it's guaranteed to show up on the NCLEX. Whether you're in clinicals or deep into your board prep, understanding how to assess and interpret FHTs can make or break your confidence when prioritizing care.

What Are Fetal Heart Tones?

Fetal heart tones refer to the audible heartbeat of a fetus, detected during prenatal assessments or labor monitoring. They can be evaluated using a Doppler, fetoscope, or electronic fetal monitor (EFM), depending on the setting.

The normal fetal heart rate (FHR) baseline is 110–160 bpm for a term fetus.

• A rate below 110 bpm is considered bradycardia.

• A rate above 160 bpm is considered tachycardia.

The primary goal of fetal heart monitoring is to assess fetal oxygenation and well-being, helping nurses intervene before distress occurs.

FHR Variability

Variability describes the fluctuations in the FHR baseline and is one of the most important indicators of fetal health.

There are four types:

• Absent: No visible changes

• Minimal: ≤5 bpm

• Moderate: 6–25 bpm (this is the ideal)

• Marked: >25 bpm

➡️ NCLEX Tip: Moderate variability is a reassuring sign of adequate oxygenation and neurologic function.

Accelerations

Accelerations are temporary increases in FHR of at least 15 bpm above baseline, lasting 15 seconds or more. They are a sign of fetal well-being and typically require no intervention.

➡️ NCLEX Tip: Accelerations = Oxygenated & OK

Decelerations

Decelerations are decreases in fetal heart rate and are classified based on their timing and shape in relation to uterine contractions:

• Early Decelerations: Mirror contractions, caused by head compression; benign and usually no intervention needed.

• Late Decelerations: Begin after the peak of contraction; associated with uteroplacental insufficiency - this is concerning.

• Variable Decelerations: Abrupt drops, unrelated to contraction timing; caused by umbilical cord compression.

Priority Nursing Interventions

Knowing what to do when fetal heart tones are abnormal is critical. Here are standard interventions:

➡️ Always reassess, notify the provider, and anticipate further interventions like a cesarean if patterns persist.

NCLEX Summary 

• Baseline FHR: 110–160 bpm

• Moderate Variability: Best indicator of fetal well-being

• Accelerations: Reassuring

• Late Decelerations: Bad - act quickly

• Use VEAL CHOP for pattern recognition

• Prioritize position changes, oxygen, fluid boluses, and stopping Pitocin as needed