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What Fetal Heart Rate Monitoring Can Reveal During Labor

For many parents, going into labor is a day filled with excitement and uncertainty. During labor and delivery, medical conditions and circumstances can change quickly, and the terminology used by medical professionals may be confusing or difficult for families to understand.

One of the most important tools used during labor is fetal heart rate monitoring. When interpreted correctly, fetal heart rate monitoring can provide early warning signs that a baby may not be receiving enough oxygen. When abnormal patterns in heart rate are missed, delays in intervention may increase the risk of oxygen deprivation and potential serious birth injury.

What Is Fetal Heart Rate Monitoring?

Fetal Heart Rate Monitoring is used to track a baby’s heartbeat during labor. It helps healthcare providers understand how the baby is responding to contractions, labor stress, and if they are receiving enough oxygen through the placenta.

Monitoring is done in two main ways:

External monitoring: A belt is placed on the mother’s abdomen to measure the baby’s heart rate and contractions
Internal monitoring: A small electrode is attached to the baby’s scalp for more direct and continuous readings

Most hospital deliveries use continuous electronic fetal monitoring with external sensors, while internal monitoring is used less frequently when a more direct assessment of the baby’s heart rate is needed.

The Patterns Doctors Look for in a Fetal Heart Rate

Instead of looking at a single heart rate value, doctors monitor the baby’s heart rate continuously to observe how it changes throughout labor.

When reviewing a fetal heart rate tracing, providers look at several different features of the baby’s heart rate pattern. These include baseline heart-rate, which is typically between 110 and 160 beats per minute, and natural beat-to-beat fluctuations known as variability. Providers also look for accelerations which are temporary increases in heart rate, and temporary decreases, called decelerations.

These patterns help healthcare providers determine how well a baby is tolerating labor and if there are signs that additional monitoring or intervention is needed. Generally, normal tracing suggests that the baby is receiving adequate oxygen and adapting well to the stresses of labor.

Normal vs. Abnormal Fetal Heart Rate Patterns

Fetal heart rate tracings are commonly grouped into categories used in obstetric practice to help healthcare providers determine how well a baby is tolerating labor.

Category I (Normal) tracings are strongly predictive of normal fetal acid-base status, meaning there is no evidence the baby is experiencing oxygen deprivation during labor. These patterns are considered reassuring and suggest the baby is tolerating labor well.

These tracings generally include:

A baseline heart rate between 110 and 160 beats per minute
Moderate variability, showing healthy beat-to-beat changes in heart rate
No concerning decelerations

Category II (indeterminate) tracings are neither clearly normal nor clearly abnormal. They include a wide range of heart rate patterns commonly seen during labor. These tracings can include a normal, elevated, or decreased baseline heart rate, depending on the overall pattern and the presence of other findings such as variability or decelerations. While these patterns do not necessarily indicate the baby is in immediate danger, they require close monitoring and ongoing evaluation because their status can change over time.

Category III (Abnormal) tracings may indicate the baby is not receiving enough oxygen and can be associated with abnormal fetal acid-base status. These patterns require prompt evaluation and intervention.

Category III tracings may include:

Absent variability with recurrent late decelerations
Absent variability with recurrent variable decelerations
Absent variability with bradycardia, which is an abnormally low fetal heart rate
A sinusoidal pattern, which is a rare but concerning wave-like heart rate pattern

When Category III patterns do not improve with intervention, urgent delivery may be necessary to reduce the risk of serious complications, including oxygen deprivation and potential brain injury called Hypoxic ischemic encephalopathy.

How Doctors Respond to Concerning Fetal Heart Rate Changes

When fetal heart rate patterns appear, medical teams often take steps to improve oxygen delivery to the baby and reduce stress during labor. Providers may reposition the mother, administer IV fluids, reduce or stop labor-inducing medications, provide supplemental oxygen, or increase monitoring.

If the baby’s heart rate pattern does not improve and signs of distress continue, doctors may determine that a more urgent delivery is necessary. In these cases, an assisted vaginal delivery using vacuum or forceps or a cesarean section may be recommended to help deliver the baby safely.

What Parents Should Understand

It is important for parents to understand that most babies with abnormal or temporary heart rate patterns are delivered safely and do not experience long-term harm. Many changes seen on monitoring strips are temporary or resolved with simple interventions.

However, when warning signs are missed, misinterpreted, or not acted upon in time, a baby may suffer serious and potentially lasting injuries related to oxygen deprivation.

Understanding how fetal heart rate monitoring works can help parents feel more informed about what is happening during delivery and why certain medical decisions are made. It may also help families recognize when warning signs during labor may have been missed or not addressed appropriately.

Do Not Wait. Get Answers Now.

At Wais, Vogelstein, Forman, Koch & Norman, LLC, our birth injury attorneys help families review medical records, including fetal heart rate tracings, to better understand what occurred during labor and delivery.

If you believe your child’s injury may be related to delayed or missed response to fetal distress, we are here to help you get answers.