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Running During Pregnancy – The Ultimate Guide

I’ve always found this subject a bit of a minefield for mums-to-be. Usually this is down to a combination of fear and misinformation. Fear of not wanting to do anything that jeopardises your pregnancy and misinformation, that is usually peddled by the mainstream media and well-meaning friends and family, not to mention Dr Google! In many cases this misinformation feeds back into the fear, and leads to mums-to-be not doing any exercise for worry of negatively effecting their’s or their babies health.

The aim of this article is to give you all the information you need, to make an informed decision on whether you want to continue running through your pregnancy or not.

I believe, that if you are given accurate information, free from marketing or ulterior motives, you are intelligent enough to make your own decisions.

I’ve looked into all the pertinent guidelines, used my own expertise as a physio and running specialist and also picked the brains of my old friend Gemma McGregor (@GMcGSpecialised). Gemma is a womens health physio, based in Peterborough, and is a wealth of information. You can follow her on twitter HERE for some great incite into womens health. I definitely recommend you do so!

Now, before we get into the meat of it, a quick disclaimer from me. What follows is general advice only, and is assumed that the reader is healthy, with no other medical issues. If you have any other medical conditions, or develop this during pregnancy, then you should discuss your running programme with your maternity team.

The following conditions require a professional medical assessment and consultation regarding whether or not physical exercise is appropriate during pregnancy:

  • Heart disease
  • Undiagnosed cardiac arrhythmia in the mother
  • Restrictive lung disease
  • Chronic bronchitis
  • Poorly controlled hypertension, thyroid disease, diabetes mellitus or epilepsy
  • Anaemia
  • Bleeding in month 4–9
  • Preeclampsia or pregnancy-induced hypertension
  • Preterm labour
  • Intrauterine growth retardation
  • Cervical weakness/cerlage
  • Preterm prelabour rupture of membranes
  • Twin pregnancy
  • Smoking > 20 cigarettes/day
  • Orthopaedic disease that limits motor capacity
  • Morbid obesity (BMI > 40)
  • Malnutrition or eating disorders (Swedish national institute of public health, 2010)


The general advice to a lady who is pregnant, and was not a runner previously, is that pregnancy may not be the best place to start. That said, The Royal College of Obstetricians and Gynaecologists (2006) state:

If you do not exercise routinely and you are starting an aerobic exercise programme, you should be advised to begin with no more than 15 minutes continuous exercise three times per week, increasing gradually to a maximum of 30 minute sessions four times a week to daily. If you exercised regularly before pregnancy, you should be able to engage in the same higher intensity exercise programmes, such as running and aerobics, with no adverse effects for you or the baby.


For those that have been running regularly prior to pregnancy you may just need a change in mindset. I think a reasonable objective should be to strive for retained fitness during pregnancy, but not to strive for peak performance (Swedish national institute of public health, 2010). As hard as it may be for the very driven out there you, will have to put your PB goals on the back burner for now.


Ok, moving on…let’s get some background and context to what we are discussing, by having a look at some of the pertinent changes your body’s going to go through as you progress through pregnancy.

The physiology of pregnancy


During your pregnancy, the need for oxygen increases, this leads to an increased respiratory depth (basically taking deeper breaths) and an increased respiratory rate. The blood volume increases by approximately two litres, which leads to a higher heart rate and greater stroke volume (the amount of blood pumped out with each beat). The resting heart rate increases by approximately 10–15 beats per minute, although with large individual differences (Swedish national institute of public health, 2010).

Hormonal changes caused by pregnancy (primarily the hormone relaxin) leads to increased flexibility in the joints. These hormonal changes effect the whole body not just the pelvic area, so commonly during running, the excessive joint laxity MAY make a pregnant lady more likely to develop musculoskeletal or pelvic girdle pain (Swedish national institute of public health, 2010). However, as long as you listen to your body and adjust intensity as needed, you should be able to monitor the load you are putting through these lax joints and you will be fine. 

I’m sure you don’t need me to tell you, but you are going to put on weight as the pregnancy develops. The pregnancy-related weight gain leads to the skeleton, muscles, joints and ligaments being placed under greater strain. At the same time, there is a forward shift in the body’s centre of balance, the back muscles are asked to do more, which creates more compression on the joints of the lower back. The curve of the back increases and, consequently, it becomes more difficult to maintain one’s balance. In pace with the growth of the belly, the distance between the rectus abdominis muscles may also increase, called diastasis recti (Swedish national institute of public health, 2010).

I bet you can’t wait after reading all of that! joking aside, it’s important to note that all the above changes are essential for preparing your body for the miracle of child birth.

Ok, let’s pause to summarise a couple of key points:


1) Accept that running in pregnancy is about staying healthy and maintaining fitness rather than reaching for peak performance.

2) Your body will change. The keys things to note for running is: your centre of balance is going to shift, your joints are going to be more lax and you are going to put on weight.



Now we know what’s going to happen to our body. Let’s be clear on the most important questions of the whole article. Is running when pregnant safe?

The NHS, the Royal College of Obstetricians and Gynaecologists and the Swedish National Institute of Public Health all agree, that in the majority of cases, physical activity (which includes running) during pregnancy is safe for mother and foetus and entails no elevated risk of abnormal pregnancy or delivery outcomes.

The research is very clear that exercising when pregnant has many benefits. These include:

  • Strengthening the cardiovascular system, which can improve the delivery of nutrients and oxygen to your baby.
  • Helps keep you fit and strong, which can help during labour and delivery.
  • Less fatigue.
  • A reduced risk of swelling in the extremities and varicose veins.
  • Less stress, anxiety, depression and sleeping disorders (Swedish national institute of public health, 2010).
  • It makes it easier to carry the weight you gain during pregnancy (Bell & Dooley, 2006).
  • You’re more likely to continue exercise post-pregnancy if you were exercising during pregnancy (Swedish national institute of public health, 2010).

With all of these benefits of exercise in pregnancy it’s hard to find  an argument to not exercise when pregnant.


So we now know that running when pregnant is perfectly safe and has lots of positive benefits for you and your baby.


The next piece of the puzzle is to get a little bit more specific with the guidance, to make sure you’re running is safe. Although we know exercise is good for you in pregnancy, a slow jog around the block is very different to a fast paced marathon in a hot and humid environment. They are both running but will obviously have very different effects on your body. So here’s a few important things to note when putting your running programmes together.


How intense should the run be?


You’re definitely going to have to tweak your intensity. Generally, heart rate is not always the most reliable way of monitoring your intensity, due to pregnancy increasing heart rate anyway. The best advice is to exercise at a moderate level of exertion. Listen to your body. You can do this in two ways 1) The talk test. Work at an intensity where you can still comfortably hold a conversation. If you become breathless as you talk, then you’re probably exercising too strenuously 2) Borg’s rating of perceive exertion (RPE) scale. This scale measures subjective exertion between 6 and 20. The recommended level during pregnancy is 12-14, in other words somewhat hard (Swedish national institute of public health, 2010)

Fig.1 Borg rating of perceived exertion (RPE) scale.

BORG scale


How long should my runs be?


I think this is going to be dependent on a few variables. One of them being the distances you were running before you got pregnant. The guidance from the Royal College of Obstetricians and Gynaecologists and the Swedish National Institute of Public Health suggest that running duration should be a max of 30-45mins. Keeping your runs to this length also decreases the risk of low blood sugar (hypoglycaemia).



Hydration is important throughout pregnancy, but especially in the first trimester. During this time there is an increase in the volume of your entire circulatory system, but there is not enough blood in circulation yet. This leads to the body doing a few things, one of which is the kidneys decrease the excretion of water and salt to the rest of the body. Therefore hydration is important, so carry some water with you when you run and drink plenty during the day.

Running in humidity and heat


This is a big one!

Both the pregnancy in itself and physical activity increase the metabolism and raises the body temperature. A body temperature of more than 39.2 degrees Celsius is believed to be teratogenic (in other words, can cause foetal damage) during the first three months. Luckily (or more due to natural selection), a higher respiratory rate and higher skin perfusion help to reduce the risk of an abnormally high body temperature (hyperthermia) (Swedish national institute of public health, 2010; Bell & Dooley, 2006)

So pay attention to environmental conditions. Humidity, heat, smoke, direct sunlight can all cause your internal body temperature to rise, and stay elevated for long stretches of time. To reduce the risk of getting too hot, you can:

●  Ensure that you drink lots of water before and during exercise.

●  Avoid over-exerting yourself (go back to the previous paragraph on intensity), particularly in the first 12 weeks of pregnancy.

●  Avoid exercising in a very hot and humid climate, until you have acclimatised –this will take a few days (Bell & Dooley, 2006).


Listen to your body


Hopefully, this is one of the themes you are picking up throughout this article. If you don’t feel right before a run, turn it into a walk or do something else like use a static bike or cross trainer, yoga, pilates and swimming are all good alternatives. Don’t push yourself and trust your first instinct. Similarly to running when not pregnant, running during pregnancy should be pain free, no “running through pain” and no pain attributed within the following 24 hours. Also, don’t ignore symptoms that could indicate a serious problem. Warning signals when physical activity should be stopped and the pregnant woman should contact women’s healthcare for a medical consultation include:

  • Pronounced breathlessness
  • Breathlessness before exercising
  • Pronounced fatigue
  • Headaches
  • Chest pains/pressure on the chest
  • Dizziness
  • Pronounced abdominal or pelvic pain
  • Painful contractions or preterm labour
  • Leakage of amniotic fluid
  • Vaginal bleeding
  • Reduced foetal movement
  • Muscle weakness
  • Swelling or pain in the calves (Swedish national institute of public health, 2010)


Tripping and falling


Be careful of tripping and falling, as this could potentially cause damage to the foetus. Remember your centre of mass is going to change, and there will come a point when you can no longer see your feet! So, try to keep the courses you run predictable, with no sudden changes of direction, or potential tripping hazards. If you run at night, make sure your route is well lit.



Physical exercise at a high altitude (> 2,500 metres) is not that common in pregnant women but I thought it would be important to mention, just in case. Running at high altitude has been shown to entail a redirection of blood from the placenta to the muscles. Theoretically, this can entail a risk that the foetus will receive too little oxygen. Therefore, at least 4–5 days of acclimation is needed to reset the metabolism (Swedish national institute of public health, 2010).

Try some added support


Some ladies will chose to use a supportive device, e.g. Belly band or compression belt, to give some extra support and proprioceptive input. Below are a couple of options. I’m led to believe that Paula Radcliffe used the belly band to run whilst she was pregnant.




Let’s pause again just to summarise that last section as there’s a lot of information in there:

Run at a moderate/somewhat hard intensity

Keep your runs to no more than 45 mins


Drink plenty of water before, during and after running. Especially in the 1st trimester


Avoid strenuous running in hot, humid environments


Listen to your body. If something doesn’t feel right then stop


Avoid dimly lit courses and tripping hazards


Avoid exercise at a high altitude (>2500 metres)


If you feel you need some extra support when you run. Try a belly band.



Extra Cheeky Tips…because I like you…


Keep your runs in a loop past your house, so you’re never far away if something happens and you need to get home quick.

Carry your mobile phone with you, for obvious reasons, but if you need to get hold of somebody quickly you’ll need your phone.

Find out where the toilets are on the route you run. Going to the toilet more frequently is often cited in pregnancy and you do not want to get caught short!

Posture – reduce lumbar lordosis (the increased curve of the spine) if possible try to use the abdominals to “hold the bump close to you” rather than let the bump hang out. 

Decrease impact and save your pelvic floor. Decreasing impact can take the pressure off your pelvic floor and prevent pelvic floor dysfunction. So to combat this you can:

  • Reduce your running distances. This gives the pelvic floor less time to fatigue under pressure. Remember it’s already working hard to hold up the weight of the baby.
  • Decrease your speed.
  • Decrease stride length/increase cadence.
  • Avoid down hill running if possible.
  • Do your pelvic floor exercises!! (10 x 10 seconds three times a day followed by 10 fast contractions.)

Phew! we’re done! So this article turned into a bit of a monster, but I hope I’ve reached my aims of providing you with all the information you need to make the best decision for you and your baby. Let’s take the fear out of running when pregnant, get educated and stay healthy!

If you have any comments on this article, or you have any other tips that may help pregnant runners, feel free to pop them in the comments box below.

mastering running technique – new e-book out soon



Professional associations for physical activity, Sweden. Physical activity in the prevention and treatment of disease. Swedish National Institute of Public Health. 2010. 

Bell and Dooley (2006). Royal College of Obstetricians and Gynaecologists. Exercise in pregnancy. statement no.4.

August 26, 2015

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