Yes, your resting heart rate increases during pregnancy, typically by 10 to 20 beats per minute by the end of the third trimester. That’s roughly a 20% to 25% jump from your pre-pregnancy baseline. So if your resting pulse was 70 bpm before pregnancy, it could climb to 80 or even 90 bpm by the time you’re close to delivery.
Why Your Heart Beats Faster During Pregnancy
Your body undergoes dramatic cardiovascular changes to support a growing baby. Blood volume alone increases by about 45%, adding roughly 1,200 to 1,600 ml of extra blood to your system. Plasma volume rises by 30 to 40%, and the total fluid outside your cells expands by 30 to 50%. Your heart has to move all that extra volume.
At the same time, your blood vessels relax and widen, which drops your vascular resistance by 25 to 30%. To compensate, your heart increases its total output by around 40%. Most of that extra pumping power comes from a bigger stroke volume, meaning your heart pushes out more blood with each beat. The heart muscle wall actually thickens slightly during pregnancy to handle this. The faster heart rate fills in the rest of the gap.
These changes start surprisingly early. By eight weeks of gestation, cardiac output has already risen by 20%.
When the Increase Starts and Peaks
Your heart rate begins climbing in early pregnancy and continues rising throughout. The peak typically comes in the third trimester. The size of the increase varies from person to person, but 10 to 20 bpm above your pre-pregnancy rate is the commonly observed range.
If you’re carrying twins, expect a higher pulse than someone with a singleton pregnancy. Research shows that pulse rates in twin pregnancies are significantly higher between weeks 11 and 30 compared to singleton pregnancies, which makes sense given the additional blood volume and metabolic demand.
How Sleeping Position Affects Your Pulse
In the third trimester especially, your position can noticeably change your heart rate. Lying flat on your back allows the weight of the uterus to compress major blood vessels, reducing the amount of blood returning to your heart. Your nervous system responds by speeding up your heart rate to compensate.
Sleeping on your left side is associated with a lower heart rate and better overall heart rate variability compared to lying on your right side or on your back. This is one reason left-side sleeping is often recommended in late pregnancy. It takes pressure off those major vessels and lets blood flow more efficiently.
What’s Normal and What’s Not
There’s no officially defined upper limit for a normal heart rate during pregnancy, which can make things confusing if you’re tracking your pulse on a smartwatch. However, the American College of Cardiology notes that most pregnant people generally stay below 120 bpm at rest, and a resting rate above 120 bpm is often considered abnormal and worth investigating.
Occasional palpitations, or moments where you notice your heart pounding or fluttering, are common in pregnancy and usually harmless. What raises concern is a persistently elevated heart rate, especially when paired with breathlessness, chest pain, dizziness, or fainting. A sustained rapid pulse in pregnancy is considered a red flag by UK maternal health reviewers and warrants a proper workup.
Exercise and Heart Rate During Pregnancy
Because pregnancy changes your baseline heart rate, using a target heart rate zone during exercise becomes less reliable. Some pregnant people show a blunted heart rate response to exercise, while others respond normally, making heart rate an inconsistent gauge of effort.
The American College of Obstetricians and Gynecologists recommends using perceived exertion instead. For moderate-intensity exercise, you should feel like you’re working “somewhat hard” but not exhausting yourself. A simple version of this is the talk test: if you can hold a conversation while exercising, you’re likely at an appropriate intensity. If you’re too breathless to talk, dial it back.
How Quickly Your Pulse Returns to Normal After Birth
Your heart rate doesn’t snap back to its pre-pregnancy level the moment you deliver. It’s actually at its highest on the day of birth, with a median of about 84 bpm. Over the first week postpartum, it drops steadily, reaching around 76 bpm by day seven. By two weeks after delivery, it settles near 75 bpm, and the decline levels off from there.
So the sharpest recovery happens in the first week, with most of the adjustment complete within about 14 days. Individual variation is wide, though. On the day of birth, heart rates anywhere from 59 to 110 bpm fall within the normal range, and by two weeks postpartum that spread narrows only slightly to 55 to 101 bpm.