Electronic Fetal Monitoring (EFM): Types, Risks and Results
Updated: 2 days ago
Written and medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: November 2026 · How we review
Quick Answer
Electronic fetal monitoring (EFM) is a test that continuously records your contractions and your baby's heart rate during labor, helping providers spot and respond to problems quickly. External EFM uses two sensors held on the belly; internal EFM uses a small wire attached to the baby's scalp. Low-risk, unmedicated labors may not need continuous monitoring.
What the research says
Continuous monitoring has trade-offs: a review of 13 trials with more than 37,000 women found continuous monitoring cut newborn seizures by half compared with listening at intervals, but didn't lower newborn deaths or cerebral palsy and raised C-section rates by 63% (Alfirevic Z et al., Cochrane Database Syst Rev, 2017) [2]
Computer reading didn't improve outcomes: in a trial of 47,062 women on continuous monitoring, computer software to help read the tracing didn't change the rate of poor newborn outcomes (0.7% in both groups) (Brocklehurst P et al., Health Technol Assess, 2018) [3]
Key takeaways
EFM continuously records your baby's heart rate and your contractions in labor.
External EFM uses two sensors on your belly.
Internal EFM uses a scalp wire and is only possible after your water breaks.
An abnormal reading doesn't always mean your baby is in danger.
Continuous EFM can lead to more C-sections and assisted births.
What is electronic fetal monitoring?
During labor, your baby's heart rate naturally changes. Watching how it responds to contractions tells your care team whether your baby is getting enough oxygen. EFM is a continuous form of fetal heart rate monitoring; the other method is intermittent auscultation, in which a nurse or midwife listens at set times with a handheld device. Sources: [1, 2]
Why it's done
Low-risk, unmedicated labor may not need continuous EFM.
Your pregnancy is high risk for any reason.
Labor is induced or assisted with medicine, such as an epidural or Pitocin.
Your baby has a congenital abnormality.
There are signs of fetal distress. Sources: [1]
EFM is sometimes used before labor too, such as after belly trauma after 20 weeks of pregnancy or to tell true labor from false labor. Sources: [1]
Types of EFM
External monitoring is the most common type.
Type | How it works | When it's used |
External (most common) | Two sensors on your belly held by elastic straps; one tracks the baby's heart rate, the other tracks contractions | Most labors that need EFM |
Internal | A small wire passed through the vagina attaches to the baby's scalp; a catheter may be placed in the uterus to measure contractions | Only after your water breaks, when external readings are unreliable or more precise readings are needed |
Sources: [1]
What happens during monitoring
The sensors or scalp wire are placed.
The monitor records your baby's heart rate and your contractions continuously.
Your care team watches the tracing on a screen or printout.
The device can sound alarms to alert the labor team. Sources: [1]
Ask your provider in the last third of pregnancy how they usually monitor your baby's heart rate during labor. Sources: [1]
Risks
Type | Possible risks |
All EFM | False alarms that cause stress; limited movement during labor; false concern for fetal distress that can lead to a C-section, vacuum or forceps delivery |
Internal EFM | Also scalp injury to the baby, uterine or vaginal infection, mother-to-baby HIV transmission and uterine or placental tears |
Large studies confirm that continuous EFM raises the rate of C-sections and instrumental births compared with intermittent listening. Sources: [1, 2]
What the results mean
An abnormal reading doesn't always mean the baby is in danger.
Finding | What it may mean |
Normal pattern | Your baby is coping well with labor |
Fast heart rate for a long time (tachycardia) | Possible problem; needs closer review |
Slow heart rate for a long time (bradycardia) | Possible problem; needs closer review |
Abnormal speeding up or slowing down | Possible stress; your team may act |
An abnormal reading doesn't necessarily mean your baby is in danger, but your team may change your position, give you oxygen by mask or IV fluids, or adjust labor medicines. If these don't help, they may recommend delivering your baby right away. Sources: [1]
Conclusion
Electronic fetal monitoring lets your care team watch your baby's heart rate throughout labor and act quickly if a problem appears. It's most useful in higher-risk labors, and knowing its trade-offs can help you talk with your provider about how you'll be monitored.
Keep learning: read about fetal heart rate monitoring and the nonstress test.
Frequently asked questions
What is electronic fetal monitoring?
A test that continuously records your baby's heart rate and your contractions during labor.
What's the difference between external and internal EFM?
External uses belly sensors; internal uses a wire on the baby's scalp.
When is internal EFM used?
Only after your water breaks, when more precise readings are needed.
Does everyone need EFM?
No. Low-risk, unmedicated labors may not need continuous monitoring.
Does EFM hurt?
External EFM doesn't hurt, though the straps can limit movement.
Can EFM cause a C-section?
False concern about fetal distress can lead to a C-section or assisted delivery.
What does a fast or slow heart rate mean?
It may signal a problem, so your team will look more closely.
Does an abnormal reading mean my baby is in danger?
Not necessarily, but your team may take steps to help your baby.
What happens if the tracing stays abnormal?
Your provider may recommend delivering your baby right away.
Can EFM be used before labor?
Yes, for example after belly trauma after 20 weeks.
Related Reading
Fetal Heart Rate Monitoring: Normal Range, Types and Decelerations the ways a baby's heart rate is checked in labor.
Nonstress Test (NST): Why It's Done, What to Expect and Reactive vs Nonreactive Results a fetal heart rate test before labor.
Contraction Stress Test: How It Works and What Results Mean a test of how the baby handles contractions.
Fetal Distress: Signs, Causes, and Management a condition EFM helps detect.
Understanding Labor Induction: A Comprehensive Patient Guide a common reason for EFM.
References
Cleveland Clinic. Electronic Fetal Monitoring (EFM): Purpose, Procedure & Results. Cleveland Clinic. Last updated August 1, 2025. https://my.clevelandclinic.org/health/diagnostics/22940-electronic-fetal-monitoring
Alfirevic Z, Devane D, Gyte GM, et al. Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. Cochrane Database Syst Rev. 2017;2(2):CD006066. PMID 28157275. https://doi.org/10.1002/14651858.CD006066.pub3
Brocklehurst P, Field D, Greene K, et al. Computerised interpretation of the fetal heart rate during labour: a randomised controlled trial (INFANT). Health Technol Assess. 2018;22(9):1-186. PMID 29437032. https://doi.org/10.3310/hta22090
Medical disclaimer
This article is for general education only and does not replace advice from a qualified healthcare professional. Talk to your doctor about your own diagnosis and treatment, and seek emergency care right away for severe or sudden symptoms.
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