What Is a Normal Fetal Heart Rate?

Is my baby's heart beat too fast?

Pregnant woman holding belly
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What is a normal fetal heart rate? This is a question that you probably have from the first time you hear your baby's heartbeat. What you hear might really surprise you. "I wish someone had prepared me for how fast it sounded. My first thought was that couldn't be the baby," remembers Eve. The truth is that a normal fetal heart rate changes during the stages of pregnancy.

At about 5 weeks gestation, your baby's heart begins to beat.

At this point, a normal fetal heart rate is about the same heart rate as the mother's: about 80-85 beats per minute (BPM). From this point, it will increase its rate about 3 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 mother has heard or seen a heartbeat is lower; however, if your doctor notices that your baby's heartbeat is off by a week or more it can indicate that a miscarriage is more likely.

"The first time we heard the heartbeat, I thought something was wrong, like my baby was having a heart attack or something. It was so fast," explains one mother. "My doctor explained that it was completely normal for it to sound like galloping horses and that it wasn't hurting my baby in any way."

By the beginning of the 9th week of pregnancy, the normal fetal heart rate is an average of 175 BPM.

At this point, it begins a rapid deceleration to the normal fetal heart rate for the middle of the pregnancy to about 120-180 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.

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

"You could hear the baby's heart rate going up and down on the monitor with contractions when I was having a non-stress test at the end of pregnancy," explains Eve. "It was pretty fascinating to see it in action. The nurse said it was a lot like exercising for you or me. The heart rate goes up and down within a certain framework of normal."

Some moms 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 mothers. 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. You should talk to your doctor or midwife about how to best monitor your baby if you are concerned.

Sources:
DuBose TJ, Cunyus JA, & Johnson L; Embryonic Heart Rate and Age. J Diagn Med Sonography 1990; 6:151-157.

Obstetrics: Normal and Problem Pregnancies. Gabbe, S, Niebyl, J, Simpson, JL. Fifth Edition.

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