How Fetal Heart Rate Changes During Pregnancy

Fetal heart rate is fastest at about 9 weeks gestation, then slows

Fetal heart rate facts

Verywell / Brianna Gilmartin 

Fetal heart rate changes throughout pregnancy. It's fastest at around 9 weeks gestation then gradually slows after the 13th week of pregnancy. But fetal heart rate by week remains faster than an adult heart rate. Many pregnant people, particularly after hearing their baby's heartbeat at a prenatal visit, may wonder what fetal heart rate is normal—and what's not. What you hear might really surprise you. Most people are not prepared for how quickly a baby's heart beats in pregnancy.

Most researchers and doctors define normal fetal heart rate as between 110 to 160 beats per minute (bpm), with some experts using narrower parameters, such as 110 to 150 bpm or 120 to 160 bpm.

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How Your Baby's Heart Rate Changes

Though there are many words to describe the moment that you first hear your baby's heartbeat, most people use words like galloping to describe how the heart rate sounds. While the heart rate in pregnancy is faster than an adult's heart rate, the truth is that a normal fetal heart rate changes during the stages of pregnancy and throughout the day.

Throughout Pregnancy

At about five weeks gestation, your baby's heart begins to beat. At this point, a normal fetal heart rate is about the same as the gestational parents': 80 to 85 beats per minute (bpm). From this point, it will increase its rate by about three beats per minute per day during that first month. This is so exact that your doctor or midwife can actually use heart rate to help pinpoint the gestational age of your baby via ultrasound.

The miscarriage rate for pregnancies in which a fetal heartbeat has been heard or seen is lower. However, if a fetal heartbeat is off by a week or more, it can indicate that a miscarriage is more likely.

By the beginning of the ninth week of pregnancy, the normal fetal heart rate is an average of 170 bpm, up from about 110 at 5 weeks gestation. After 13 weeks gestation, it begins a rapid deceleration to the normal fetal heart rate for mid-pregnancy, between 110 to 160 bpm. There is also a slowing of the normal fetal heart rate in the last 10 weeks of pregnancy, though the normal fetal heart rate is still about twice the normal adult's resting heart rate.

Interestingly, research shows that toward the end of pregnancy fetal heart rate differs between male and female babies, with female fetuses having noticeably higher heart rates.

Normal Fetal Heart Rate by Week
Gestation in Weeks 20-24 28-32 34-38
Average Fetal Heart Rate in Beats per Minute (bpm) 110 170 144 140 136

Throughout the Day

Your baby's normal fetal heart rate will also vary naturally throughout the day and night, just as your own heart rate does. Movement, sleeping, and other activities can cause normal variation. Be sure to talk to your midwife or doctor about any concerns that you have with your baby's heart rate.

If you are having a non-stress test at the end of pregnancy, you can hear the fluctuations. The heart rate goes up and down within a certain framework of normal. Imagine what it would sound like if you had ongoing audio of your heart rate as you were starting to exercise and then cooling down. Your heart rate would go up and down as well. Your baby has the same reaction.

Monitoring Baby's Heart Rate

Some parents may wonder if monitoring the baby's heart rate from day to day while at home is a smart idea. But the practice has pros and cons.

At Home

Some parents feel better when they can monitor the baby's heartbeat from home. This use of a doppler in the home is not recommended for most people. The concerns are multi-pronged and include overuse of the doppler listening device and/or misinterpretation, positively or negatively.

There are other ways to listen to your baby's heartbeat. Talk to your doctor or midwife about how to best monitor your baby if you are concerned.

In Labor

Fetal monitoring in labor can be done by intermittent auscultation, which means listening with a stethoscope, fetoscope, or handheld doppler at various points in labor. Your baby may be monitored intermittently with an external monitoring belt. Or your practitioner may recommend continuous monitoring, either external or internal.

Each of these practices has benefits and tradeoffs for you and your baby, depending on your labor and your medical history. Talk to your doctor or midwife for advice on which is best for you. In general, low-risk pregnancies will need less monitoring in labor.

However, during the process of labor, your baby may show signs of needing more intense monitoring or your labor or interventions may require increased monitoring to help boost the safety of procedures. For example, even if you are low risk, if you have a Pitocin induction of labor you will likely have continuous external monitoring.

A Word From Verywell

You may worry when you first hear the heartbeat that something is wrong because it sounds so different than what you may be used to hearing. Rest assured, it is most likely normal. Ask your practitioner for advice if you are concerned.

4 Sources
Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Valenti O, Di Prima FA, Renda E, Faraci M, Hyseni E, De Domenico R, Monte S, Giorgio E. Fetal cardiac function during the first trimester of pregnancy. J Prenat Med. 2011;5(3):59-62

  2. Pildner von Steinburg S, Boulesteix AL, Lederer C, Grunow S, Schiermeier S, Hatzmann W, Schneider KT, Daumer M. What is the "normal" fetal heart rate? PeerJ. 2013;1:e82. doi:10.7717/peerj.82

  3. ACOG Practice Bulletin No. 106: Intrapartum fetal heart rate monitoring: nomenclature, interpretation, and general management principles. Obstet Gynecol. 2009;114(1):192-202. doi:10.1097/aog.0b013e3181aef106

  4. Shuffrey LC, Myers MM, Odendaal HJ, Elliott AJ, du Plessis C, Groenewald C, Burd L, Angal J, Nugent JD, Isler JR, Fifer WP; PASS Network. Fetal heart rate, heart rate variability, and heart rate/movement coupling in the Safe Passage Study. J Perinatol. 2019;39(5):608-618. doi:10.1038/s41372-019-0342-9

Additional Reading
  • As Low As Reasonably Achievable (ALARA) Principle. American Institute for Ultrasound in Medicine.

  • Obstetrics: Normal and Problem Pregnancies. Gabbe, S, Niebyl, J, Simpson, JL. Seventh Edition; 2016.

  • Stamatopoulos N, Lu C, Casikar I, Reid S, Mongelli M, Hardy N, Condous G. Prediction of subsequent miscarriage risk in women who present with a viable pregnancy at the first early pregnancy scan. Aust N Z J Obstet Gynaecol. 2015 Oct;55(5):464-72. doi: 10.1111/ajo.12395. Epub 2015 Aug 21.

By Robin Elise Weiss, PhD, MPH
Robin Elise Weiss, PhD, MPH is a professor, author, childbirth and postpartum educator, certified doula, and lactation counselor.