If you caught my last post on the Biophysical Profile Score (BPS), you know I’m all about auditing the data during this third trimester. While the ultrasound covers the visuals, the Non-Stress Test (NST) is all about the audio—specifically, the baby’s heart rate in relation to their movement.
I was recently advised to do this, and it’s actually a pretty relaxing (if technical) 20 minutes of me-time with the baby.
NST FAQ: The Technical Breakdown
What exactly is an NST? It’s a non-invasive test where two sensors are placed on your belly: one monitors the baby’s heart rate and the other tracks any uterine activity or contractions. No needles, and no stress. It’s just you, a comfortable chair, and a lot of clicking.
Why is it done? The goal is to see how the baby’s heart rate reacts when they move or when the uterus contracts. In my case, I was advised to take the NST because of my white coat hypertension.
Expert Note: If you haven’t heard of it, White Coat Hypertension is basically when your blood pressure spikes specifically because you’re in a clinical or hospital setting (the “white coats” make you nervous!), even if your readings are perfectly normal at home. Since blood pressure can impact the placenta, my OB wanted that extra layer of data to ensure the baby is doing well.
Decoding the Results: The 10/10 Connection
In my BPS post, we talked about aiming for an 8/8 on the ultrasound. The NST provides the final 2 points.
8 points from the Ultrasound (Movement, Tone, Breathing, Fluid)
2 points from the NST based on heart rate reactivity.
Total: 10/10 Seeing that perfect score on your report is the ultimate reassurance that the womb environment is optimized, and there’s nothing to worry as the baby’s wellbeing is fine.
What I Learned From My Results
During my session, the monitor actually picked up some Braxton Hicks contractions. It was so interesting to see them visualized on the paper! While knowing I’m having practice contractions is nice, my OB highlighted the difference of Braxton Hicks contractions to a real in-labor contractions. Braxton Hicks contractions happens only once, while in-labor contractions happen in a certain frequency and pattern.
The most important takeaway? Even during those contractions, the baby’s heartbeat stayed strong and responsive.
Common Findings & What to Look For
Reactive: This is the goal! it means the baby’s heart rate accelerated as expected during movement.
Non-Reactive: This doesn’t always mean something is wrong. The baby might just be napping! Usually, they’ll give you some juice or a snack to wake them up and try again.
Questions to Ask Your OB
When you’re reviewing your Non-Stress Test (NST) strip or report with your doctor, don’t be afraid to be curious and list down your questions. Here are three questions I always keep ready:
1. How was the variability of the heart rate? (This is a key sign of a healthy nervous system).
2. Were the results enough to change our plans of delivery?
3. Are there any follow-up tests I need to do?
The NST isn’t just another laboratory test. It’s a chance to know how your baby’s doing before they get delivered. Getting those final 2 points to hit a 10/10 score is the best kind of peace of mind.
