C-EFM key terms

The average fetal heart rate, rounded to the nearest 5 beats per minute, measured over a 10-minute window and excluding accelerations, decelerations, and periods of marked variability. At least 2 minutes of interpretable tracing are required to establish it.

The amplitude and frequency of fluctuations in the fetal heart rate baseline, reflecting the interplay of the sympathetic and parasympathetic nervous systems. It is classified as absent, minimal, moderate, or marked, and moderate variability is the expected normal finding.

An undetectable range of fluctuation in the fetal heart rate baseline on a tracing with adequate signal quality. It may reflect fetal sleep, maternal medication or substance exposure, or fetal acidemia, and warrants further evaluation.

Baseline fluctuation greater than undetectable but no more than 5 beats per minute. It can be a normal variant during fetal quiescence but may also accompany fetal hypoxemia, so the overall pattern and clinical context guide interpretation.

Baseline fluctuation of 6 to 25 beats per minute, considered the normal and reassuring finding that strongly predicts the absence of fetal metabolic acidemia at the time of observation.

Baseline fluctuation exceeding 25 beats per minute. It may occur with fetal activity, maternal fever or infection, medication effects, or cord compression, and its significance depends on associated patterns.

An abrupt increase in fetal heart rate above the baseline lasting at least 15 seconds. At or beyond 32 weeks the peak must reach 15 beats per minute above baseline; before 32 weeks a 10-beat rise lasting 10 seconds qualifies.

A gradual decrease in fetal heart rate that mirrors a uterine contraction, with onset, nadir, and recovery timed to the contraction's beginning, peak, and end. It is generally attributed to fetal head compression and is usually benign.

A gradual decrease in fetal heart rate that begins after the start of a uterine contraction and returns to baseline after the contraction ends. It suggests uteroplacental insufficiency and is considered nonreassuring.

An abrupt decrease in fetal heart rate, defined as a drop of at least 15 beats per minute lasting at least 15 seconds and less than 2 minutes, with onset unrelated to contraction timing. It most often reflects umbilical cord compression.

A decrease in fetal heart rate from baseline of at least 15 beats per minute lasting 2 minutes or longer but less than 10 minutes. Duration of 10 minutes or more is reclassified as a baseline change.

A smooth, undulating fetal heart rate baseline with a frequency of 3 to 5 cycles per minute and amplitude of 5 to 15 beats per minute, persisting at least 20 minutes, with absent variability and no accelerations. It raises concern for fetal anemia.

A fetal heart rate tracing with a normal baseline of 110 to 160 beats per minute, moderate variability, no late or variable decelerations, and accelerations that may be present or absent. It is considered normal and predictive of normal fetal acid-base status.

An abnormal tracing with absent variability plus recurrent late or variable decelerations, or with bradycardia, or with a sinusoidal pattern. It predicts abnormal fetal acid-base status and calls for prompt evaluation and intervention.

A baseline fetal heart rate below 110 beats per minute that persists for at least 10 minutes. Causes include maternal hypotension, cord prolapse, uterine hyperstimulation, and fetal cardiac conduction abnormalities.

A baseline fetal heart rate above 160 beats per minute lasting at least 10 minutes. It may accompany maternal fever, infection, dehydration, fetal anemia, or maternal medication exposure.

The presence of two or more qualifying accelerations within a specified monitoring period, indicating an intact fetal autonomic nervous system. Reactivity is a key reassuring feature on both antepartum and intrapartum tracings.

A temporary tightening and shortening of the uterine muscle that generates pressure within the uterus and may reduce placental blood flow at its peak. Frequency, duration, intensity, and resting tone are the parameters assessed.

The baseline pressure within the uterus between contractions, typically estimated by palpation as soft or by an intrauterine catheter in millimeters of mercury. Elevated tone can impair placental perfusion and warrants investigation.

More than five contractions in a 10-minute window, averaged over 30 minutes. It is described as hyperstimulation when accompanied by nonreassuring fetal heart rate changes, and management focuses on restoring normal uterine activity.

Excessive uterine contraction frequency or resting tone associated with nonreassuring fetal heart rate patterns. Common responses include reducing or stopping oxytocin, repositioning the patient, and administering a tocolytic agent if needed.

A sterile fluid-filled device placed into the amniotic cavity to measure contraction intensity and resting tone in millimeters of mercury. It is used when external palpation or tocodynamometry cannot provide adequate contraction assessment.

An external pressure transducer secured over the uterine fundus that records the timing and relative frequency of contractions. It does not measure contraction intensity reliably and is affected by maternal position and body habitus.

The external device placed on the maternal abdomen that uses Doppler shift to detect fetal heart motion and convert it into an audible and displayed heart rate. Correct placement and gel application are essential for signal quality.

A spiral or clip electrode attached to the fetal presenting part through the cervix after membrane rupture, providing a direct fetal electrocardiogram signal. It is used when external monitoring is unreliable but carries infection and injury risks.

Absence or intermittent dropout of the recorded fetal heart rate caused by transducer displacement, maternal movement, or poor signal quality. It requires prompt correction because uninterpretable tracings can mask deterioration.

Periodic listening to the fetal heart rate with a Doppler device or fetoscope during and between contractions, with the rate counted for a set interval and documented. It is an acceptable monitoring method for low-risk laboring patients.

Continuous recording of the fetal heart rate and uterine activity, displayed as a tracing for ongoing interpretation. It may be external or internal and is used to detect patterns suggesting fetal hypoxemia.

An antepartum test that records the fetal heart rate while the fetus is unstimulated, looking for accelerations that demonstrate reactivity. It is typically performed for 20 to 40 minutes and may be extended if the fetus is asleep.

An antepartum assessment combining a nonstress test with ultrasound evaluation of fetal breathing, movement, tone, and amniotic fluid volume. Each component is scored, and the total score estimates fetal well-being.

A semiquantitative ultrasound measure of amniotic fluid obtained by summing the deepest vertical pockets in each of four quadrants. Low values may indicate placental insufficiency and increased risk of cord compression.

An antepartum test that observes the fetal heart rate response to induced uterine contractions, typically produced with oxytocin or nipple stimulation. Late decelerations with adequate contractions indicate a concerning result.

Reduced blood flow across the placenta, limiting oxygen and nutrient delivery to the fetus. It is the classic explanation for late decelerations and may be associated with growth restriction and oligohydramnios.

Mechanical compression of the umbilical cord that transiently reduces blood flow between fetus and placenta. It commonly produces variable decelerations, and management includes maternal repositioning and fluid administration.

A reduction in fetal hemoglobin or red cell mass, often from hemolytic disease or fetal hemorrhage. It may produce a sinusoidal heart rate pattern and is evaluated with middle cerebral artery Doppler studies.

An abnormal accumulation of fluid in two or more fetal compartments, such as ascites, pleural effusion, or skin edema. It can result from severe anemia, infection, or cardiac failure and signals serious fetal compromise.

A set of bedside actions to improve fetal oxygenation when the tracing is nonreassuring, including maternal repositioning, intravenous fluids, oxygen if indicated, reducing uterine activity, and correcting maternal hypotension.

A synthetic hormone used to induce or augment labor by stimulating uterine contractions. Its dose is titrated to contraction pattern, and excessive uterine activity or nonreassuring fetal heart rate changes require dose reduction or discontinuation.

An elevated maternal body temperature, often from chorioamnionitis or other infection, that can raise the fetal heart rate and blunt variability. It warrants evaluation for infection and fetal status assessment.

The contemporaneous, accurate written or electronic record of monitoring findings, interventions, and communications. Complete documentation supports clinical decision-making, continuity of care, and legal defensibility.

The structured process of reporting concerning fetal monitoring findings to the responsible clinician and confirming that a response was received. Clear escalation and closed-loop confirmation are essential professional responsibilities.