Quick Reference
Normal fetal heart rate: 110–160 BPM (beats per minute)
This range applies from approximately 10 weeks through the end of pregnancy. A fetal heart rate outside this range — particularly if consistently below 110 BPM or above 180 BPM — warrants prompt contact with your OB or midwife.
Fetal Heart Rate by Trimester
| Stage | Normal Range | Average | Notes |
|---|
| 6–8 weeks | 90–110 BPM | ~100 BPM | Early cardiac activity; detected only via transvaginal ultrasound |
| 8–10 weeks | 150–170 BPM | ~160 BPM | Rapid rise during cardiac development |
| 10–12 weeks | 155–195 BPM | ~170 BPM | Peak rates during early development |
| 12–20 weeks | 140–170 BPM | ~155 BPM | Begins to stabilize |
| 20–28 weeks | 120–160 BPM | ~140 BPM | More stable; reactive to movement |
| 28–40 weeks | 110–160 BPM | ~135 BPM | Mature range; should accelerate with movement |
Your HeartBeats™ LCD display will show the detected BPM in real time. Normal readings at 12+ weeks should fall between 110 and 160 BPM.
Why Fetal Heart Rate Changes Throughout Pregnancy
First Trimester (Weeks 6–12)
The fetal heart is one of the first organs to develop. In the early embryonic period (weeks 6–8), the heart rate rises rapidly as cardiac conduction tissue matures. Peak rates of 160–195 BPM are normal during weeks 8–12 — this is NOT dangerous; it reflects active cardiac development.
Second and Third Trimester
As the autonomic nervous system matures, the fetal heart rate becomes regulated by the same parasympathetic and sympathetic balance that governs adult heart rate. The rate gradually falls from its first-trimester peaks toward the mature range of 110–160 BPM.
Reactivity
From about 28 weeks onward, a healthy fetus demonstrates heart rate reactivity — the heart rate accelerates in response to:
- Fetal movement
- External stimulation (sound, touch)
- Sleep-wake cycles (drops slightly during fetal sleep)
If your baby is in a sleep cycle during monitoring, the heart rate may be at the lower end of normal and less reactive. Wait 20–30 minutes and try again.
What to Do If the Reading Seems Abnormal
Possible Explanations for Unexpected Readings
| Reading | Most Likely Explanation |
|---|
| 60–90 BPM | You’ve found YOUR heart rate (maternal pulse), not baby’s |
| >170 BPM before 20 weeks | Normal — see table above |
| >170 BPM after 20 weeks | Could be baby’s movement, maternal fever, or needs evaluation |
| <110 BPM consistently | Needs medical evaluation |
| Erratic/jumping numbers | Probe movement artifact; reposition and try again |
When to Call Your Provider
Contact your OB or midwife promptly if:
- You consistently read below 100 BPM and are confident it’s the fetal signal (not your pulse)
- You cannot find the heartbeat and you have been able to find it easily in previous sessions (especially after 20 weeks)
- Fetal movement has decreased
Do not use the absence of a detected heartbeat as confirmation of fetal loss — position issues, early gestational age, and technique can all prevent detection. Only clinical evaluation can confirm fetal wellbeing or otherwise.
Maternal vs Fetal Heart Rate: How to Tell the Difference
A very common experience is detecting your own pulse (60–80 BPM) rather than the fetal heartbeat. Here’s how to distinguish them:
| Signal | Your Pulse | Fetal Heartbeat |
|---|
| BPM range | 60–80 BPM | 110–160 BPM |
| Sound quality | Dull “thump” or “whoosh” | Rapid “galloping horse” |
| Feels like | Syncs with your own pulse you can feel | Distinctly faster; you can’t feel it |
Related: How to Use · First Trimester Guide · FAQ
