Fetal Heart Rate

What Fetal Heart Rate Measures

Fetal heart rate is exactly what it sounds like: how fast the fetal heart beats, in beats per minute. It's one of the earliest things a clinician can observe directly in a pregnancy. On ultrasound, fetal heart tones can be picked up between six and eight weeks of gestation.^[1]

How It's Measured

Two tools do most of the work. Early on, ultrasound shows cardiac activity on screen and measures the rate as part of the scan.^[1] Later, the handheld Doppler device, the small wand most people meet at routine prenatal visits, turns the moving heart into the sound you hear in the room. Doppler can pick up fetal heart tones as early as around ten weeks of gestation.^[2] Either way, it's a clinician's measurement made with clinical equipment. What people track at home is the number from the visit, not a reading of their own.

Why People Track It

Prenatal appointments spread out across months, and each one produces a reading that usually ends up buried in a visit summary or a patient portal. Logging the number and its date after each appointment puts every reading on one timeline, next to the rest of the pregnancy record. That's useful for the same reason any longitudinal record is: it keeps the history in one place you can actually find.

For how pregnancy tracking apps handle this kind of appointment data, see our guide to the best pregnancy tracking apps.

How Go Go Gaia Tracks It

Go Go Gaia has a fetal heart rate log built in. After an appointment, you enter the reading in one tap and the app charts it on your pregnancy timeline, next to fundal height and anything else you're logging. Every reading from every visit stays in one record.

What the Research Shows

Fetal heart rate changes fast in the first trimester. A study of 4,698 singleton pregnancies built reference charts for embryonic heart rate at 6 to 10 weeks and found the relationship between rate and gestational age at that stage isn't a straight line.^[3] A reading at seven weeks and a reading at nine weeks come from different points on a steep curve.

Later in pregnancy the picture flattens out. An analysis of 78,852 fetal heart rate tracings from three German hospitals found the median baseline rate drifts down slowly across pregnancy, by about 0.4 beats per minute per week.^[4] The same study pointed out that guideline bodies don't fully agree on how to define the normal range, which is one more reason reading any individual trace is the clinician's job, not the chart's.^[4]

Related Terms

Frequently Asked Questions

Educational information based on published sources. Not medical advice. For personal concerns, please consult your doctor.

When can a fetal heartbeat be detected?

On ultrasound, fetal heart tones can be picked up between six and eight weeks of gestation. A handheld Doppler device, the kind used at prenatal visits, can pick up fetal heart tones as early as around ten weeks. The exact timing varies from pregnancy to pregnancy and depends on the equipment.

Does fetal heart rate stay the same through pregnancy?

No. In the first trimester the rate changes quickly from week to week, and researchers describe the relationship between rate and gestational age at 6 to 10 weeks as non-linear. Later in pregnancy, a large study of fetal heart rate tracings found the median baseline drifts down slowly, by about 0.4 beats per minute per week.

Who measures fetal heart rate?

A clinician does, with an ultrasound scan or a handheld Doppler device at a prenatal visit. It's a clinical measurement, and interpreting any reading is your doctor's or midwife's job. What many people do is record the number from each appointment so their readings sit on one timeline.