This post may contain affiliate links. Read the full disclosure here.
Last Updated on November 18, 2023 by theosteomum
Many pregnant women know by now that they probably should do some exercise, but want to know if there’s such a thing as a safe pregnancy exercise heart rate?
There’s been a lot of confusion and, frankly, wrong information in the past in this area.
These days there has been a lot of research into the area of exercise in pregnancy.
Moms-to-be can feel quite safe in the knowledge that if they stick to the guidelines outlined in this post, they’ll only be doing both themselves and their babies good.
In this post, we’ll cover:
- The benefits of exercise during pregnancy
- Things to be aware of when exercising during pregnancy
- Is there a safe pregnancy exercise heart rate?
- How much can/should I do?
- How much can I exercise during pregnancy?
- What types of exercise are considered “safe” during exercise?
- Exercises to avoid during pregnancy
- Other things to avoid with exercise during pregnancy
- What happens to your baby when you exercise during pregnancy?
- When you should stop exercising while pregnant
In this article we’ll dive deep into not only these questions, so you can feel completely certain about the best way(s) to exercise during pregnancy.
The benefits of exercise during pregnancy
What are the benefits of exercise during pregnancy?
The short answer is- plenty!
Not only can you exercise during pregnancy, but you should be doing it.
Physical inactivity and excessive weight gain have been associated with a number of complications during pregnancy. The best known of these is gestational diabetes.
And you don’t need to just take my word for it.
The World Health Organisation and American College of Obstetricians and Gynaecologists agree with me.
The WHO clearly states:
“The benefits of exercise during pregnancy far outweigh the risks.”
So, why all the encouragement to get you doing some exercise during pregnancy?
It’s because there are so many health benefits for both you and your baby!
Women who regularly exercise during pregnancy have:
- A higher incidence of vaginal delivery compared to women who don’t exercise. This means that they’re more likely to avoid the need for emergency caesarians, and all of the possible complications that go along with them.
- A lower incidence of:
- Excessive weight gain during pregnancy
- Gestational diabetes
- Disorders such as gestational high blood pressure or preeclampsia
- Preterm birth
- Cesarean birth
- Lower birth weight (i.e. their babies are more likely to be born in an ideal weight range)
- Postnatal depression
As you can see, there are so many positives that can come out of exercise during pregnancy.
Things to be aware of with exercise during pregnancy:
When exercising during pregnancy, you’ll need to be more careful than usual not to overheat. This is especially important in the first trimester, as higher core temperatures have been associated with neural tube defects in the unborn child.
For the “average” woman doing a “regular” amount of exercise, this should not be a problem.
Studies have shown that women’s core temperatures did not increase to dangerous levels when exercising for up to 35 minutes at 80-90% of their maximum heart rate at temperatures of 25 degrees Celsius (77 degrees Fahrenheit).
It’s also important to ensure you’re drinking plenty of water, and wear comfortable clothing that allows your skin to breathe.
Keeping cool will ensure you sustain an ideal pregnancy exercise heart rate, as your heart beats faster when you’re hot.
So if you live in a warm climate, it may be best to choose the coolest part of the day to exercise where possible.
Is there a safe pregnancy exercise heart rate?
For most women, no, there isn’t considered to be a single number that is considered a safe pregnancy exercise heart rate.
You may have heard that pregnant women should not increase their heart rate above 140 beats per minute.
This is based on the first ever official advice published by ACOG (the American College of Obstetricians and Gynaecologists) back in 1985.
Not exactly current evidence.
These guidelines also advised against high impact exercise such as running, which we also know to be safe in many women.
Why don’t we talk about a safe pregnancy exercise heart rate anymore?
The problem with limiting pregnant women to a certain heart rate is that it doesn’t take into account all of the other variables that surround this number.
I.e. at any given time, your heart rate only tells part of the story.
Limiting pregnant women to a certain heart rate doesn’t factor in things like:
- each individual’s maximum heart rate,
- their percieved level of exertion at a particular heart rate, and
- how active they were prior to becoming pregnant.
Why pregnancy exercise heart rate is not important reason #1:
Your maximum heart rate:
Each of us has a specific maximum heart rate, which is the most number of times per minute that our heart can beat.
The rough calculation for this has always been listed as (220 – your age), however, we also now know that this isn’t totally accurate.
For example, I’m almost 40, meaning that my theoretical maximum heart rate would be 220-40 = 180 beats per minute.
I also regularly exercise at a heart rate of around 185 beats per minute, which would be impossible if the above formula were true.
The (220- your age) formula is now only used as a rough guide to gain an estimate of your maximum heart rate, and should be taken into consideration with a number of other variables.
What we do know for certain is that your maximum heart rate decreases as you get older.
Your heart just can’t quite pump as often at 40 as it did at 20.
Sigh.
So, as many women are having babies later now than they did in the past, their theoretical maximum heart rate will be lower while pregnant than it was if they had children when they were younger.
Limiting these women to 140 beats per minute would place a further barrier to exercise during pregnancy, which is the exact opposite of what we know to be ideal.
Why pregnancy exercise heart rate is not important reason #2:
Your perceived level of exertion
Ever done an exercise class with someone who seems to breeze through, while you’re a hot, sweaty, panting mess?
It may be that they’re just “fitter” than you right now, and they can do the same exercise at a lower heart rate.
Or, it may be that they’re better adapted to working at that particular heart rate, and it no longer feels hard for them.
What feels like an 8 or 9 out of 10 for you only feels like a 5 or 6 to them.
Their perceived level of exertion for that effort and heart rate is less than yours.
Limiting women to exercising at a particular heart rate would completely ignore this possibility.
Why pregnancy exercise heart rate is not important reason #3:
How active you were prior to becoming pregnant
Looking at how active you were prior to becoming pregnant is an extension of the second point above.
Let’s look at a comparison between two different women.
Woman A has run several times per week for many years. Woman B has never regularly exercised.
Woman A can sustain what feels like a moderate effort of running for a given period of time, whereas Woman B may struggle to make it around the block without feeling short of breath.
The same activity can feel very different for both women, depending on how much of it they’ve done in the past.
And yet, when you take their heart rate, they may be not too far off each other.
This is yet another reason why we now discuss perceived level of effort, which we’ll discuss in more detail below.
How much can I exercise during pregnancy?
Guidelines recommend that you perform at least 150 minutes of moderate intensity exercise per week.
That’s about 2.5 hours.
This applies to both the pregnancy, and the period of time after you give birth.
These 150 minutes should be spread out throughout the week.
You could aim for 30 minutes on at least 5 days of the week, or break it up in whatever timetable suits your schedule.
If you’re wondering how hard you can safely push yourself during exercise during pregnancy, take a look at the chart below.
The “sweet spot” to aim for is around a 13-14, which falls somewhere between “somewhat hard” and “hard”.
It’s important to note, however, that many women find that exercise they found easy before pregnancy will begin to feel more difficult.
This is due to a variety of changes taking place within your body.
Your safest strategy is to continue to evaluate how hard you feel you’re working, as this will continue to change.
Another simple test to ensure you’re exercising safely during pregnancy is to use the “talk test“.
Aim to be able to continue a conversation when exercising.
This should help ensure you’re not overdoing it.
What types of exercise are safe during pregnancy?
The types of exercise that are safe during pregnancy include:
- Walking- either outdoors or on a treadmill
- Stationary cycling (using an exercise bike or putting your bike on a stationary trainer)
- Aerobic exercises, such as exercise classes or workout videos at home
- Dancing
- Resistance exercises (eg, using weights and resistance bands)
- Stretching exercises, such as Yoga
- Hydrotherapy and water aerobics. These forms of exercise have also been shown to be effective strategies to help deal with pelvic girdle pain. You can read more about this here.
What types of exercise aren’t considered safe during pregnancy?
As your pregnancy progresses, your growing belly will mean that your centre of gravity changes.
This means that your balance probably won’t be quite as good as it was before you were pregnant.
As a result, activities that rely on your balance to keep you safe are best kept until after Bub arrives.
A classic example of this type of activity is cycling.
It would most likely feel a lot harder to maintain your balance or react swiftly on a bike at 8 months pregnant than it would when you’re not pregnant.
This can lead to a higher chance of falls, meaning that cycling is often not recommended for pregnant women.
This leads on to the next point of avoiding potential falls or knocks to your growing belly.
Contact sports such as football or netball are often best avoided during pregnancy, as it’s impossible to ensure that your opponents or teammates won’t (even accidentally) collide with your belly.
Finally, scuba diving and exercising at altitudes higher than 6,000m above sea level (unless you already live at this altitude) are also off the list of safe types of exercise during pregnancy.
This is because of changes in how your body deals with breathing and respiration while you’re pregnant.
Even at the best of times it can be harder to breathe at such high altitudes. Add in a pregnancy and it can be just all too much for your body to cope with.
Other things to avoid with exercise during pregnancy:
Along side the activities such as cycling that you should avoid during pregnancy, there is another important point that you need to be aware of.
After around 20 weeks of pregnancy, the weight of the baby can put pressure on the large blood vessel that helps return blood back to your heart if you lay on your back.
This can cause a decrease in blood flow to your baby, which can result in serious complications.
To avoid this, it’s safest to avoid laying on your back for more than a few minutes at a time from around 20 weeks of pregnancy onwards.
This can be important when performing exercises such as Pilates, where you may have previously spent a lot of time laying on your back.
Of course you can still perform Pilates moves, you’ll just need to modify them so you’re not spending time laying on your back.
“What happens to my baby when I exercise during pregnancy?”
It’s thought that your baby’s heart rate increases by around 10-30 beats per minute during and after exercise in pregnancy.
However, this does not seem to have any negative effects on the unborn child.
So it seems that your baby’s heart may beat a little faster when you exercise during pregnancy.
However, their heart rate is already quite fast (120-160 beats per minute on average), so adding in a few more beats is a relatively small adjustment.
Some babies born to women who continue to exercise vigorously into their third trimesters may be born between 200-400g lighter than those born to mothers who do not exercise at this level.
Once again, however, this does not appear to indicate foetal growth restriction.
So, the evidence suggests that there may be some small adaptations in babies whose mothers exercise regularly during pregnancy, but not enough to outweigh all of the known benefits to both of them.
When to stop exercising while pregnant:
In most healthy women with uncomplicated pregnancies, you can continue to exercise all throughout the pregnancy.
If you are affected by certain conditions during your pregnancy, you should be guided by your Doctor or Midwife’s advice.
However, below is a list of warning signs that something may be wrong, and that you should stop exercise immediately and seek medical advice:
- Vaginal bleeding
- Abdominal pain
- Regular, painful contractions (as opposed to Braxton Hicks, which you can read about here)
- Aminotic fluid leakage
- Shortness of breath or difficulty breathing even before you exert yourself
- Dizziness
- Headache
- Chest pain
- Any muscle weakness that affects your balance
- Calf pain or swelling
If any of these apply to you, please speak to your medical team ASAP for advice on your exact circumstances.
Safe pregnancy exercise heart rate- wrapping up:
Exercise during pregnancy is a great way to improve your health, both during pregnancy, labour and beyond.
In an uncomplicated pregnancy, it’s safe to push yourself to a perceived level of effort of 13 or 14 out of 20. This level of effort is one you’d describe as “somewhat hard” to “hard”.
You should be aiming for at least 2.5 hours of moderate intensity exercise per week.
Be careful to avoid overheating, as well as activities that rely on your balance, carry a high risk of knocks to your belly, or are performed at high altitudes.
What types of exercise would you like to try during pregnancy?
I’d love to hear your thoughts.
And don’t forget to share this article with your pregnant friends who may have been reluctant to break a sweat!
