Clinical Review

How to differentiate maternal from fetal heart rate patterns on electronic fetal monitoring

Author and Disclosure Information

 

References

Follow 3 steps to discern fetal vs maternal heart rate

These cases illustrate the difficulties in recognizing maternal heart rate patterns on the fetal monitor tracing. The 3 simple steps described below can aid in differentiating maternal from fetal heart rate patterns.

1 Be aware and alert

Recognize that EFM monitoring of the maternal heart rate may occur during periods of monitoring, particularly in second-stage labor. Often, the recorded tracing is a mix of fetal and maternal patterns. Remember that the maternal heart rate may increase markedly during the second stage and rise even higher during pushing efforts. When presented with a tracing that ostensibly represents the fetus, it may be challenging for the clinician to question that assumption. Thus, be aware that tracings may not represent what they seem to be.

Often, clinicians view only the 10-minute portion of the tracing displayed on the monitor screen. I recommend, however, that clinicians review the tracing over the past 30 to 60 minutes, or since their last EFM assessment, for an understanding of the recent fetal baseline heart rate and decelerations.

2 Investigate

Although it is sometimes challenging to recognize EFM maternal heart rate recordings, this is relatively easy to investigate. Even without a pulse oximeter in place, carefully examine the EFM recording for maternal signs to determine if the maternal heart rate is within the range of the recording. You can confirm that the recording is maternal through 1 of 3 easy measures:

  • First, check the maternal radial pulse and correlate it with the heart rate baseline.
  • Second, place a maternal electrocardiographic (EKG) heart rate monitor.
  • Last, and often the simplest approach for continuous tracings, place a finger pulse oximeter to provide a continuous maternal pulse reading. Should the maternal heart rate superimpose on the EFM recording, maternal patterns are likely being detected. However, since the pulse oximeter and EFM Doppler devices use different technologies, they will provide similar—but not precisely identical—heart rate numerical readings if both are assessing the maternal heart rate. In that case, take steps to assure that the EFM truly is recording the fetal heart rate.

3 Treat and correct

If the EFM is recording a maternal signal or if a significant question remains, place a fetal scalp electrode (unless contraindicated), as this may likely occur during the second stage. Alternatively, place a maternal surface fetal EKG monitor, or use ultrasonography to visually assess the fetal heart rate in real time.

Key point summary

The use of a maternal finger pulse oximeter, combined with a careful assessment of the EFM tracing, and/or a fetal scalp electrode are appropriate measures for confirming a fetal heart rate recording.

The 3 steps described (be aware and alert, investigate, treat and correct) can help you effectively monitor the fetal heart rate and avoid the potentially dangerous outcomes that might occur when the maternal heart rate masquerades as the fetal heart rate.

Share your thoughts! Send your Letter to the Editor to rbarbieri@mdedge.com. Please include your name and the city and state in which you practice.

Pages

Recommended Reading

Maternal use of pot and tobacco may boost birth defect risk
MDedge ObGyn
Are we using the right metrics to measure cesarean rates?
MDedge ObGyn
No strong evidence linking vitamin D levels and preeclampsia
MDedge ObGyn
Could tackling maternal obesity prevent later CVD in offspring?
MDedge ObGyn
NSAID use early in pregnancy increases miscarriage risk
MDedge ObGyn
Research provides more evidence of a maternal diabetes/autism link
MDedge ObGyn
Urge expectant parents to have prenatal pediatrician visit
MDedge ObGyn
Does expectant management or induction of labor at or beyond term result in better birth outcomes?
MDedge ObGyn
Human trafficking: How ObGyns can—and should—be helping survivors
MDedge ObGyn
2018 Update on infectious disease
MDedge ObGyn