Share this on:Copied!

If you’ve delivered a baby, you’ve likely experienced electronic fetal monitoring (EFM). This test monitors and displays a baby’s heart rate and the uterus’s contractions during labor.

EFM helps to assess a baby’s status during labor, allowing the care team to provide treatment if necessary.

“Today, in the United States, almost all labors are managed with continuous electronic fetal heart rate monitoring,” says Hyagriv Simhan, MD, director, Patient Care Delivery and Innovation, UPMC, and executive vice chair, Obstetrics, UPMC Magee-Womens Hospital.

“Some of that has to do with the use of the technology itself to manage the health of moms and babies. But (it’s also useful) for managing a unit, a hospital in which many labors are taking place, to be able to keep eyes on a fetus, even without someone at the bedside at that moment. Continuous electronic fetal heart rate monitoring has allowed hospitals to be able to do that.”

Learn more about electronic fetal monitoring during labor. Discover how it works, and its benefits and risks.

What Is Electronic Fetal Monitoring?

Electronic fetal monitoring uses technology to measure the fetal heart rate and the frequency and intensity of contractions during labor. It allows care teams, including physicians, nurses, and midwives, to manage the health of mother and baby during labor.

Fetal heart rate monitoring became popular as a screening tool in the 1970s. Today in the United States, it’s used for over 90% of patients in active labor, according to the journal Obstetrics and Gynecology.

During labor, EFM can help check for evidence of fetal distress. The most common sign is fetal hypoxia, or a lack of oxygen getting to the baby. Care teams can then take steps to address the situation, such as:

• Changing the mother’s position.
• Giving intravenous fluids.
• In some situations, delivering the baby immediately via cesarean section or with forceps or vacuum assistance.

A similar test, called the nonstress test, can measure how a baby’s heart rate changes in response to movement during pregnancy. Providers typically will use nonstress tests for high-risk pregnancies. EFM, meanwhile, takes place in almost all labors.

Continuous vs. intermittent monitoring

EFM during labor measures the baby’s heart rate and contractions continuously. An alternative to electronic fetal monitoring is intermittent auscultation (IA). In intermittent auscultation, the provider checks the baby’s heart rate periodically during labor.

Providers use intermittent auscultation much less often than EFM, Dr. Simhan says.

“The vast majority of labors in the United States are managed with continuous electronic fetal heart rate monitoring,” he says.

How Does Electronic Fetal Monitoring Work?

EFM uses technology during labor and delivery to track the baby’s heart rate and the contractions of the uterus.

There are two types of fetal heart rate monitoring: external and internal.

In external monitoring, a sensor is placed on the mother’s abdomen and held in place by a strap. The sensor uses Doppler technology to track the baby’s heart rate. The heart rate displays on a computer monitor.”

“With each heartbeat, the valves move, which creates motion, which creates sound,” Dr. Simhan explains. “That sound can be detected by the Doppler device and translated in the monitor itself to a number, which is the heart rate.”

In internal heart rate monitoring, a sensor called an electrode is placed on the baby’s scalp inside the uterus. It measures the heart rate by using the heart’s electrical activity.

Internal heart rate monitoring can only take place once the mother’s water breaks. Care teams use it less often than external monitoring.

How does contraction monitoring work?

Contractions can also be monitored externally or internally.

In external monitoring, a sensor placed on the abdomen records changes in intra-abdominal pressure that occur during a contraction. Internal monitoring places a small catheter (tube) next to the baby in the uterus to measure intrauterine pressure.

Like fetal heart rate monitoring, external contraction monitoring is more common than internal.

What Are the Pros and Cons of Fetal Heart Rate Monitoring?

What are the benefits of electronic fetal monitoring?

Electronic fetal monitoring allows providers to monitor the baby’s health during labor. It helps care teams detect signs of fetal distress, such as the baby not getting enough oxygen.

If there are signs of non-reassuring fetal status, care teams can take steps to manage the situation. Potential interventions include:

• Adjusting medications.
• Administering intravenous fluids.
• Changing the mother’s position.
• Performing an immediate delivery, if necessary.

Immediate delivery occurs only if more conservative measures aren’t successful, Dr. Simhan says.

“The idea is to be able to inform interventions to help improve oxygen delivery to a baby and allow labor to continue,” he says. “We’ve done interventions to conservatively manage abnormalities. But in some instances, those abnormalities can’t be conservatively managed, and cesarean delivery or assisted vaginal delivery is performed because ongoing labor would be felt to increase the risk of harm to the baby.”

EFM has helped to reduce stillbirths and fetal strokes after birth, Dr. Simhan says.

What are the risks of electronic fetal monitoring?

Mothers often have to stay in bed during EFM to avoid affecting the sensors. This may cause discomfort.

There is also a risk of “false positives.” A care team may see the data from EFM, determine that there are signs of distress, and perform unnecessary interventions.

Does EFM Increase the Risk of a Cesarean Delivery?

Cesarean sections (C-sections) have increased in the United States since EFM became popularized:

• Over 30% of babies are born by C-section today, according to a 2023 review in the American Journal of Obstetrics & Gynecology. The number was below 5% in the 1970s.
• Over 25% of primary cesarean deliveries occur because of signs of fetal distress indicated by EFM, according to the American College of Obstetrics and Gynecology (ACOG).

Dr. Simhan says the issue often comes down to how the care team interprets the EFM data.

“No test, under any circumstance, is perfect,” he says. “With this one in particular, it’s also an interpretation issue. Teams of labor and delivery nurses and OB providers, midwives, and doctors need to be aware of optimal monitoring, and that real-world performance of any medical test is oftentimes not the same as it is in a laboratory or scientific experimental setting.”

ACOG recommends that care teams try several conservative measures before moving to a cesarean delivery. These include:

• Changing the mother’s position.
• Performing amnioinfusion (adding amniotic fluid to the uterus).
• Providing IV fluids.
• Reducing or stopping induction medications.
• Addressing other issues that could be causing fetal distress.

“It’s not that our only choice is to watch the monitor and if something’s abnormal, do a C-section,” Dr. Simhan says. “There are other things short of cesarean delivery that are indicated when we monitor and see certain features.”

How Safe Is EFM for Mother and Baby?

Electronic fetal monitoring is a safe childbirth monitoring tool. It allows care teams to track the baby’s health. If EFM detects signs of fetal distress, teams can take appropriate action.

ACOG says that the benefits of fetal heart rate monitoring outweigh the risks. Most patients should receive EFM, ACOG adds.

“There are really clear benefits, and therefore by not getting monitoring, you lose a lot of those benefits as well,” Dr. Simhan says. “We do what we can to try to minimize the cesarean deliveries that don’t need to happen, and I think everyone in obstetrics tries to do that. But the reality is today in the United States, a monitored labor is safer than an unmonitored labor.”

Dr. Simhan says labor and delivery teams should be able to provide clear explanations to patients about why interventions like a cesarean delivery might be necessary. That helps patients and care teams share in informed decision-making.

UPMC labor and delivery teams go through extensive training that explains EFM and how to apply the results, Dr. Simhan says. UPMC also developed a vocabulary for EFM interpretation to ensure clear communication. That helps ensure safe and effective use of EFM.

“We want to make sure that everyone’s on the same page, communicating using the same language, with a common understanding,” he says. “So that’s something we’ve developed internally here and spread across not just UPMC Magee, but all of our obstetrical facilities at UPMC.”

UPMC Magee is a National Center of Excellence in Women’s Health and a national leader in obstetrics and gynecology care. To learn more about the services we provide, visit our website.