Nonstress Test: Must-Know Insights for Your Baby’s Health

Medical, Pregnancy

If you’re pregnant and have been told you need a non-stress test (NST), you might be wondering what that actually means, what doctors are looking for, and why it’s such a common part of prenatal care. As a Labor and Delivery nurse and student midwife, I’m here to break it down for you so you can feel confident and informed. Let’s dive into what a non-stress test is, why it’s done, and what we look for during the test.

What Is a Non-Stress Test (NST)?

A non-stress test is a routine, non-invasive test commonly used during pregnancy to check on the well-being of your baby. It’s typically done to ensure that your baby is receiving enough oxygen and is handling the stresses of pregnancy well. While it doesn’t provide long-term answers about how the baby will do once born, it gives us an immediate snapshot of how your baby is doing at that moment.

Why Do We Do Non-Stress Tests?

Non-stress tests are done for a variety of reasons:

To monitor baby’s health: NSTs are especially common for pregnancies that are considered high-risk, such as those involving gestational diabetes, high blood pressure, or if the baby is overdue.
To check baby’s oxygen levels: NSTs are one of the best ways to assess if your baby is getting enough oxygen.
To observe fetal heart rate patterns: This test helps track the baby’s heart rate to see how well they’re doing in the womb.

An NST can be done as part of your regular prenatal checkups, especially if you are past 24 weeks of pregnancy. It’s a great way to reassure both you and your healthcare provider that things are progressing smoothly.

Hello! Wanted to send a thank you for all the incredible content and podcasts you share. I was able to have a natural birth this last Saturday and had listened or practiced a ton of the things you all share. I worked out regularly through my pregnancy and added in some of the training recommendations you had. I also made a list of things to do in each phase or labor, and when the nurses would tell me where baby was at in my pelvis I immediately could adjust my position or use different ideas. The birth comb got me through contractions, and it honestly blows my mind that I was able to do it naturally. Thanks for sharing such amazing info!

Thank you so much for the content you share! I just had my first unmedicated birth with no interventions, after having epidurals and pitocin in my first two deliveries. I used so much of your advice on stretches and exercises leading up to labor and tips for labor and pushing! Between you ladies and having a doula for the first time. I felt so confident in the type of delivery I wanted to have and I was able to achieve it! And with the help of my Rockstar hubby too! Thank you SO much!

I just had to reach out and say thank you thank you for your amazing brain and program! I followed your shorter version for the prenatal program (with a 2 and 3 year old, it was the perfect amount). Up until birth, I felt incredible, like literally no discomfort like my other 2 pregnancies. I went in to spontaneous labor at 40 and 1 (I’ve never experienced spontaneous labor and last pregnancy, I went 42 and 4 and still didn’t go in to labor on my own). As well as this birth I achieved a VBA2C. You played a big part in this pregnancy journey, and I cannot recommend you enough with anyone looking for ways to prepare for birth! 💜

What Are We Looking for During a Non-Stress Test?

The non-stress test involves monitoring your baby’s fetal heart rate (FHR) and checking for fetal movements. Here’s what we look for:

Fetal Heart Rate Baseline: The first thing we check is your baby’s baseline heart rate, which should be between 110 and 160 beats per minute. This tells us that the baby is stable and in a good range for their development.
Heart Rate Variability: We also assess the variability in the heart rate, which refers to how much the heart rate fluctuates from beat to beat. A healthy baby will show moderate variability, meaning the heart rate will change by at least 5 to 25 beats above and below the baseline. If variability is too low (minimal variability) or too high (marked variability), it can signal that we need to look into things further. The worst-case scenario is absent variability, where the heart rate stays constant without any fluctuations, which could be a sign of a problem.
Accelerations: Next, we’re on the lookout for accelerations in the heart rate. These are brief increases in the fetal heart rate, which should be 10–15 beats per minute above the baseline for at least 10–15 seconds. If the baby is under 32 weeks gestation, we want a 10 by 10 acceleration (10 beats for 10 seconds). If they’re over 32 weeks, we want a 15 by 15 acceleration. We need to see two accelerations during the test to feel confident that the baby is doing well.

What Happens During the Test?

The non-stress test usually takes 20 to 40 minutes. During this time, you’ll be asked to lie down while two monitors are placed on your belly. These monitors will track your baby’s heart rate.

Here’s how it works:

Monitor 1 checks your baby’s heart rate.
Monitor 2 listens for fetal movements.
You may be asked to push a button when you feel your baby move so we can see the correlation between the movement and the heart rate changes.

In most cases, if we don’t see the accelerations in the first 20 minutes, we can extend the test for up to 40 minutes. This gives us more time to catch the baby outside their natural sleep cycle. Just like adults, babies sleep, and during this time, their heart rate may not show the variability or accelerations we need to see. Giving them a full 40 minutes allows us to accurately assess their health when they’re awake.

What If We Don’t See Accelerations?

If after 30 minutes we haven’t seen the desired accelerations, one option we have is to use a vasoacoustic stimulator—it’s a device that emits a vibrating sound to gently “wake up” your baby. This can be helpful if your baby is in a deep sleep, but we want to make sure they’re reacting to the stimuli properly.

Non-Stress Test vs. Contraction Stress Test

It’s important to note that the non-stress test does not require you to be having contractions, which is why it’s called a “non-stress” test. However, if you’re in labor, you may experience contractions during the test, but they aren’t the focus.

In contrast, a contraction stress test involves inducing contractions to see how well your baby tolerates the stress of labor. This is more commonly done if your doctor is concerned about your baby’s ability to handle labor.

Comfort During the Non-Stress Test

One of the great things about a non-stress test is that it doesn’t require you to stay completely still. If you need to move around or get up, feel free to do so—as long as the monitors can still track your baby’s heart rate and movements. This can be especially helpful if you’re having contractions, as it allows you to move in ways that feel more comfortable.

Conclusion

A non-stress test (NST) is a quick, non-invasive, and highly valuable tool for checking on your baby’s health. We’re looking for a steady heart rate, good variability, and accelerations to make sure your baby is oxygenated and thriving. If you’re told you need an NST, know that it’s simply a precautionary step to ensure that everything is going smoothly with your pregnancy.

If you’ve had an NST during your pregnancy, I’d love to hear about your experience! And if you have any other questions about your pregnancy journey, send them to us!

If you’re looking for additional support during your pregnancy, check out our online childbirth education courses and prenatal fitness programs to help you stay informed, prepared, and strong throughout this amazing journey!

Biophysical Profile Test: Must-Know Insights for Your Baby’s Health

December 2, 2024 No Comments

If your healthcare provider has recommended something called a “biophysical profile” during your pregnancy, you might be left wondering what it is and why it’s

Roxanne Albert, BSN, RNC-OB