How to Calculate Fetal Heart Rate

15 Seconds 30 Seconds 60 Seconds (Full Minute) 10 Seconds

Understanding Fetal Heart Rate (FHR)

The fetal heart rate (FHR) is a vital sign used by medical professionals to monitor the health and well-being of a developing baby during pregnancy and labor. While modern Doppler devices and ultrasounds provide automated readings, understanding the manual calculation is essential for using a fetoscope or a handheld Doppler accurately.

How to Manually Calculate Fetal Heart Rate

To calculate the FHR manually, you need to count the number of audible beats over a specific timeframe and then convert that number into Beats Per Minute (BPM). The most common clinical practice involves counting for 15 seconds or 60 seconds.

The Formula

The math behind the calculation is straightforward:

BPM = (Number of Beats / Seconds Observed) × 60

Calculation Example

If you are using a Doppler and you count 38 beats in a 15-second window, the calculation would look like this:

• Beats: 38
• Interval: 15 seconds
• Math: (38 / 15) × 60 = 152 BPM

In this scenario, the fetal heart rate is 152 BPM, which falls within the normal range for most stages of pregnancy.

Normal Fetal Heart Rate Ranges

A baby's heart rate changes throughout the pregnancy. Early in the first trimester, it may start slower, peak around week 9, and then stabilize.

Stage	Normal Range (BPM)
6-7 Weeks	90 – 110 BPM
9 Weeks	140 – 170 BPM
Mid-to-Late Pregnancy	110 – 160 BPM

Disclaimer: This calculator is for educational purposes only. If you have concerns about a fetal heart rate, please consult with an obstetrician or a qualified healthcare provider immediately.

function calculateFHR() { var beats = document.getElementById("fhrBeats").value; var seconds = document.getElementById("fhrSeconds").value; var resultDiv = document.getElementById("fhrResult"); var bpmValueDisp = document.getElementById("bpmValue"); var statusDisp = document.getElementById("fhrStatus"); if (beats === "" || beats <= 0) { alert("Please enter a valid number of beats."); return; } var bpm = (parseFloat(beats) / parseFloat(seconds)) * 60; var roundedBpm = Math.round(bpm); resultDiv.style.display = "block"; bpmValueDisp.innerHTML = roundedBpm + " BPM"; if (roundedBpm 160) { statusDisp.innerHTML = "Status: Above Average (Tachycardia risk)"; statusDisp.style.color = "#d32f2f"; resultDiv.style.backgroundColor = "#ffebee"; } else { statusDisp.innerHTML = "Status: Normal Range"; statusDisp.style.color = "#2e7d32"; resultDiv.style.backgroundColor = "#e8f5e9"; } }