What Do Contractions Look Like on Paper? | Paper Traces

On a fetal monitor paper strip, contractions appear as bell-shaped curves on the bottom graph.

If you’re in labor and a nurse hands you a long strip of paper with two wavy lines, it’s normal to feel a little lost. The top line tracks your baby’s heartbeat; the bottom line records your uterine contractions. Those bottom waves look like a series of hills—each hill is one contraction. The peak of the wave represents when the uterus is fully tight.

Learning what those hills represent can help you understand your labor’s rhythm. The contraction curve rises as the uterus tightens, peaks at the strongest point, and falls as it relaxes. This article explains what a healthy pattern looks like on paper and how to read key details like frequency and duration.

Your care team will always take the lead, but having the basics can make the monitor less mysterious. Think of the bottom line as a map of your contractions, with each wave marking a step forward in your labor.

Decoding the Two Lines on Your Monitor Strip

The fetal monitor paper strip has two separate sections. The top graph displays the fetal heart rate (FHR) in beats per minute. The bottom graph tracks uterine activity, and the peaks on this graph correspond to the tightening of the uterus during a contraction.

Each contraction typically looks like a bell-shaped curve or hill. The peak of the wave represents the strongest point of the contraction, when the uterus is fully tight. Between contractions, the line returns to a lower baseline—showing that the uterus has relaxed.

The duration of a contraction is timed from when it first begins until it is completely over, usually measured in seconds. Frequency is measured from the start of one contraction to the start of the next, including the rest period. For example, a contraction lasting one minute and occurring every three minutes is a common pattern in active labor.

Clinicians also assess baseline tone—the tension of the uterus between contractions—which should be low and consistent. Regularity of the hills (even spacing) can suggest true labor rather than Braxton Hicks. This pattern is considered efficient: the uterus works hard, then rests completely.

Why Those Waves Tell a Story About Your Labor Progress

The pattern of your contraction waves gives your care team important clues about progression. Frequency, duration, intensity, baseline tone, and regularity—each reveals something about how your uterus is working. A regular pattern with gradually increasing strength often signals active labor, while erratic hills may mean you’re still in early labor. ACOG defines a normal contraction frequency as five or fewer in 10 minutes, averaged over 30 minutes.

• Frequency: Number of contractions per 10 minutes, measured from the start of one hill to the start of the next.
• Duration: Length of each contraction from start to end, shown by the width of the hill on paper.
• Intensity: Estimated from the height of the wave (taller = stronger), though not precise without an internal monitor.
• Baseline tone: Resting level of the bottom line between contractions; should be low and stable.
• Regularity: Whether the intervals between hills are consistent; irregular spacing often happens in early labor.
• Tachysystole: More than five contractions in 10 minutes, which may require attention to ensure baby gets enough oxygen.

Your care team looks at the whole strip, not just one hill. Changes over time are more revealing than a single readout. If you notice anything that looks different, ask your nurse to explain what it means. If you see speeding up or slowing down, it’s worth mentioning to your nurse.

How Contraction Patterns Relate to Fetal Heart Rate

The top graph tracks fetal heart rate, which often responds to contractions with slight dips or accelerations. Both can be normal, especially if the heart rate recovers quickly. Coordination between the two lines is what clinicians watch most closely.

ACOG defines tachysystole as more than five contractions in 10 minutes. Some sources use a lower limit of four to prevent fetal stress. Resources like the NCBI’s fetal heart rate classification explain how clinicians assess fetal response during labor.

Abnormal patterns, such as variable decelerations that dip with each contraction, may signal cord compression. Normal heart rate variability (amplitude ≥10 bpm) is reassuring. The “Rule of 3” for bradycardia is sometimes mentioned, but it’s not a universal standard.

These measurements help clinicians determine if your labor pattern is typical.

How to Read Your Contraction Strip: A Simple Guide

If you want to follow along with your monitor, start by finding the bottom graph. That’s the line showing uterine activity. Here’s a step-by-step walkthrough for reading the contraction pattern. Remember that the top line is the baby’s heart rate—don’t confuse the two. The monitor doesn’t measure pain—just the physical contraction—so don’t worry if your sensations don’t perfectly match the wave height.

1. Find the hills. Look at the bottom graph for wave-like curves that rise and fall. Each hill is one contraction.
2. Identify the start of a hill. Note where the line begins to rise from its resting baseline. That marks the beginning of a contraction.
3. Count frequency. Measure from the start of one hill to the start of the next. That interval is your frequency (e.g., every 3 minutes).
4. Measure duration. From the start of the hill to where it returns to baseline is the length of the contraction. It’s usually 30–90 seconds.
5. Check rest periods. The distance between the end of one hill and the start of the next is the rest period. In active labor, it’s typically 1–2 minutes.

With practice, you can glance at the bottom graph and quickly see if contractions are getting closer and lasting longer—two signs labor is progressing. But don’t worry about perfect reading; your care team tracks all the details.

When Contraction Patterns Signal Something Different

Most contraction patterns are reassuring, but some changes deserve attention. Tachysystole—more than five contractions in 10 minutes—can reduce oxygen flow to the baby. If you see very tall hills with little rest between them, mention it to your nurse. Your nurse can tell you if your pattern falls into a concerning range.

Variable decelerations are dips in the fetal heart rate that often coincide with contractions, such as during cord compression. Per the University of South Florida guidelines on variable decelerations contractions, these patterns are common and often resolve on their own but may require repositioning or oxygen if persistent.

The “Rule of 3” for bradycardia is sometimes cited to guide emergency response: if the heart rate stays below normal for >3 minutes, call for help; >6 minutes, move to the operating theatre; >9 minutes, prepare for assisted delivery; >12 minutes, aim to deliver. However, this is not a universal protocol and should not replace your care team’s judgment.

The Bottom Line

Reading a contraction monitor strip doesn’t require medical training. The bottom graph’s bell-shaped curves show each contraction’s timing and pattern. Tracking frequency and duration can help you understand your labor’s progress, but the real experts—your labor nurse, midwife, or doctor—interpret the full picture. Use your knowledge to feel engaged, not anxious. A strip is just a snapshot; labor is a dynamic process.

Your labor nurse or midwife can point out the hills on your specific strip and explain what they mean for your baby’s heart rate pattern. Don’t hesitate to ask—they’re used to questions from curious parents.