Why heart rate increases during pregnancy is linked to the amazing changes your body makes to support your growing baby.
You glance at your smartwatch and do a double take.
Your resting heart rate is higher than usual.
Climbing a flight of stairs leaves you slightly more breathless.
You become more aware of your heartbeat while lying in bed.
Naturally, questions start appearing.
“Why is my heart beating faster?”
“Is this normal during pregnancy?”
“Should I be worried?”
Quick Answer
Heart rate increases during pregnancy because the body needs to pump more blood to support the growing baby and placenta. As blood volume rises by up to 50%, the heart works harder to deliver oxygen and nutrients throughout the body. For many women, a resting heart rate increase of 10 to 20 beats per minute is considered a normal part of pregnancy.
As a women’s health physiotherapist, I hear these concerns frequently.
Heart rate changes are among the most noticeable yet least understood adaptations of pregnancy.
The truth is that pregnancy places extraordinary demands on the cardiovascular system.
Your heart is no longer working solely for you.
It is supporting a growing baby, a developing placenta, an expanding blood supply, and a body undergoing remarkable transformation.
In most healthy pregnancies, an increase in heart rate is completely normal.
In fact, it is one of the ways your body successfully adapts to the needs of pregnancy.
Understanding why this happens can help you feel more confident about the changes occurring inside your body and recognize when symptoms are likely part of normal pregnancy physiology.
Key Takeaways
- Heart rate normally increases during pregnancy to support maternal and fetal circulation.
- Many women experience a resting heart rate increase of 10 to 20 beats per minute.
- Blood volume may increase by approximately 40% to 50% during pregnancy.
- The placenta requires a constant blood supply, increasing cardiovascular demands.
- The heart pumps more blood with each beat and often beats faster.
- Shortness of breath can occur because oxygen requirements increase during pregnancy.
- Occasional palpitations are common and are often related to normal physiological changes.
- Smartwatch heart rate readings often increase during pregnancy.
- Exercise remains beneficial for most women with uncomplicated pregnancies.
- Chest pain, fainting, or severe shortness of breath should always be medically evaluated.
Why Your Heart Works Harder During Pregnancy
The heart is one of the hardest-working organs during pregnancy.
From the earliest weeks, the cardiovascular system begins adjusting to support the growing baby.
These changes occur long before many women even develop a visible baby bump.
Pregnancy Creates New Demands
During pregnancy, the body must:
- Deliver oxygen to the baby
- Deliver nutrients to the baby
- Support placental growth
- Remove waste products
- Increase circulation throughout the body
All of these tasks require additional blood flow.
The heart responds by working more efficiently and pumping more blood. (Priya et al. 2016)
This increased workload is one of the main reasons heart rate rises during pregnancy.
How Much Does Heart Rate Increase?
Many women worry when they notice their pulse climbing.
Fortunately, some increase is expected.
A Typical Increase
Research suggests that heart rate often increases by approximately 10 to 20 beats per minute during pregnancy. (Cleveland Clinic)
For example:
- A resting heart rate of 65 may rise to 75 or 85.
- A resting heart rate of 70 may increase to 80 or 90.
These changes vary between individuals.
Why Every Woman Is Different
Several factors influence heart rate, including:
- Fitness level
- Age
- Hydration
- Activity levels
- Stage of pregnancy
- Stress levels
This is why comparing your heart rate to someone else’s pregnancy is rarely helpful.
The Blood Volume Connection
One of the most important reasons heart rate increases is because blood volume increases dramatically.
Your Body Produces More Blood
Pregnancy requires a larger blood supply.
Maternal blood volume may increase by approximately 40% to 50%. (Mayo clinic)
That is an extraordinary adjustment.
Imagine adding nearly half again as much blood to your circulation.
Why More Blood Is Needed
The additional blood helps:
- Supply oxygen to the baby
- Deliver nutrients
- Support placental function
- Prepare for blood loss during birth
This expanded blood supply creates additional work for the cardiovascular system.
The Heart Must Keep Up
More blood means more circulation.
More circulation means the heart must pump more frequently and efficiently.
A higher heart rate helps accomplish that goal.
Did You Know?
By the third trimester, a pregnant woman’s heart may pump up to 50% more blood per minute than before pregnancy. This extraordinary adaptation helps deliver oxygen and nutrients to both the mother and the growing baby.
Why The Heart Pumps More Blood
Heart rate is only part of the story.
The amount of blood pumped with each heartbeat also changes.
Cardiac Output Increases
Cardiac output refers to the amount of blood the heart pumps every minute.
Pregnancy significantly increases cardiac output.
Think Of It Like A Delivery System
Imagine a delivery company suddenly needing to serve twice as many customers.
It can either:
- Send trucks more frequently
- Increase the amount each truck carries
Pregnancy does both.
The heart pumps more blood per beat and increases heart rate to meet demand.
The Role Of The Placenta
One of the most overlooked reasons heart rate increases is the placenta.
The Temporary Organ With A Huge Job
The placenta is responsible for:
- Oxygen exchange
- Nutrient delivery
- Hormone production
- Waste removal
It requires a constant and reliable blood supply.
Supporting Two Circulations
The mother’s circulation must now support both:
- Maternal tissues
- Placental circulation
This added demand contributes significantly to cardiovascular adaptations.
Many women focus exclusively on the baby and forget that they are also supporting an entire temporary organ.
Why You May Feel Breathless
One of the most common pregnancy symptoms is shortness of breath.
Many women assume this means they are out of shape.
In reality, pregnancy physiology often explains it.
Increased Oxygen Demand
Pregnancy increases oxygen requirements.
The body needs oxygen for:
- Maternal tissues
- Placental function
- Fetal development
As demand rises, breathing patterns change. (Head et al. 2008)
The Diaphragm Moves Upward
As the uterus expands, it gradually pushes the diaphragm higher into the chest.
This changes breathing mechanics.
Many women report:
- Needing deeper breaths
- Feeling winded more easily
- Increased awareness of breathing
These changes are often normal.
Why Breathlessness And Heart Rate Are Connected
When oxygen demands increase, the cardiovascular and respiratory systems work together.
A faster heart rate helps transport oxygen more efficiently throughout the body.
Palpitations During Pregnancy
Another symptom that often causes concern is palpitations.
What Are Palpitations?
Palpitations are sensations such as:
- Fluttering
- Skipped beats
- Strong heartbeats
- Racing heartbeat
Many pregnant women experience occasional palpitations.
Why They Happen
Possible contributors include:
- Increased blood volume
- Hormonal changes
- Stress
- Fatigue
- Anxiety
- Increased awareness of body sensations
When They Feel More Noticeable
Many women notice palpitations:
- While resting
- While lying down
- At night
This is often because there are fewer distractions competing for attention. (Cleveland Clinic)
What Your Smartwatch Might Notice
Modern technology has changed how women experience pregnancy.
Many pregnant women track:
- Heart rate
- Sleep
- Activity
- Exercise
Why Smartwatch Data Can Be Confusing
A higher resting heart rate often alarms women who are accustomed to seeing lower numbers.
However, pregnancy frequently changes baseline readings.
What Matters More
Trends are often more important than individual numbers.
A modest increase may simply reflect normal pregnancy adaptations.
However, sudden or dramatic changes should always be discussed with a healthcare professional.
Don’t Let Technology Create Unnecessary Fear
Smartwatches can provide useful information.
They cannot interpret pregnancy physiology.
Context always matters.
Exercise And Pregnancy Heart Rate
One of the biggest misconceptions surrounding pregnancy is that an increased heart rate means exercise should be avoided.
Current evidence does not support that idea.
Exercise Remains Important
For most healthy pregnancies, physical activity provides significant benefits.
Benefits may include:
- Improved fitness
- Better circulation
- Reduced discomfort
- Improved mood
- Better energy management
The Old 140 Beats Per Minute Rule
Years ago, women were often advised to keep their heart rate below 140 beats per minute.
This recommendation is now considered outdated.
A Better Approach
Many experts recommend using perceived exertion or the talk test.
If you can comfortably maintain a conversation during exercise, intensity is often appropriate.
A Physiotherapist’s Perspective
When pregnant women notice heart rate changes, the first reaction is often fear.
Most of the time, those changes are normal.
The cardiovascular system is adapting exactly as it should.
Focus On The Bigger Picture
Rather than focusing on a single number, consider:
- How you feel
- Energy levels
- Breathing comfort
- Exercise tolerance
- Overall wellbeing
Support Your Cardiovascular System
Simple habits can help:
- Stay hydrated
- Move regularly
- Change positions gradually
- Prioritize rest
- Maintain balanced nutrition
These habits support circulation and overall health throughout pregnancy.
Respect Your Body’s Signals
Pregnancy is not the time to ignore symptoms.
Pay attention to changes, but remember that many cardiovascular adaptations are expected and healthy.
Physiotherapist’s Advice
If your heart rate feels higher than usual during pregnancy, focus on hydration, regular movement, proper breathing, and gradual position changes. These simple habits can support circulation and help your cardiovascular system adapt more comfortably to pregnancy.
When A Fast Heart Rate Needs Medical Attention
Although increased heart rate is common during pregnancy, some symptoms require evaluation.
Contact your healthcare provider if you experience:
- Chest pain
- Severe shortness of breath
- Fainting
- Persistent dizziness
- Sustained racing heartbeats
- Significant palpitations
- Symptoms that feel unusual or concerning
It is always better to ask questions than to ignore symptoms that worry you.
Final Thoughts
Your heart is performing one of the most impressive jobs in the human body during pregnancy.
It is circulating extra blood, supporting the placenta, delivering oxygen to your baby, adapting to changing hormones, and responding to increased physical demands every single day.
Seen from that perspective, a higher heart rate makes perfect sense.
As a physiotherapist,
I encourage women to view these cardiovascular changes not as signs that something is wrong, but as evidence of how remarkably adaptable the body truly is.
Pregnancy asks more of the heart than almost any other normal life event.
The increase in heart rate is one of the many ways your body rises to meet that challenge and helps create the ideal environment for your growing baby.
Frequently Asked Questions About Heart Rate During Pregnancy
Is it normal for heart rate to increase during pregnancy?
Yes. A higher heart rate is a normal pregnancy adaptation because the cardiovascular system must support both mother and baby.
How much does heart rate increase during pregnancy?
Many women experience an increase of approximately 10 to 20 beats per minute compared to their pre-pregnancy resting heart rate.
Why does my smartwatch show a higher heart rate?
Pregnancy increases blood volume and cardiac output, which can naturally raise resting heart rate readings.
Can pregnancy cause palpitations?
Yes. Many women notice occasional palpitations due to increased blood volume, hormonal changes, and heightened awareness of their heartbeat.
Does a higher heart rate affect my baby?
In most healthy pregnancies, a moderately increased maternal heart rate is a normal adaptation and helps support fetal growth and placental function.
Can exercise raise heart rate during pregnancy?
Yes. Exercise naturally increases heart rate, and appropriate physical activity remains beneficial for most pregnant women.
When should I worry about a fast heart rate?
Seek medical advice if a fast heart rate is accompanied by chest pain, fainting, severe shortness of breath, or persistent dizziness.
Why do I feel more breathless during pregnancy?
Pregnancy increases oxygen requirements and changes breathing mechanics, which can make everyday activities feel more demanding.
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Medical Disclaimer!
This article has been reviewed and written under the guidance of our Head Physiotherapist, Dr. Kruti Raj (PT, MUHS,CPT,CMPT). The information shared is intended for educational purposes only and should not be considered a substitute for personalized medical advice, diagnosis, or treatment.
Please consult us or any other qualified healthcare professional before beginning any exercise program, especially if you are experiencing pain, recovering from injury, or managing a medical condition.
