How your changing body impacts exercise during pregnancy

Lyz Evans
Lyz Evans
Lyz is the founder of Women In Focus Physiotherapy. An industry leading pelvic health clinic in Sydney. She has her Masters in Women’s health and Continence Physiotherapy and is also a mum of two herself.
Created on Oct 15, 2023 · 5 mins read

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So, we all know that the pregnant belly grows so large that you can’t even see your own undies, but there are many other adaptations that are occurring below the surface that you need to be aware of.

Heart rate

Incredibly, the body produces 50% more blood in pregnancy, which means the heart is working harder to pump this blood around every single second of every single day. This is why when exercising at an intensity that was previously not challenging, in pregnancy it will feel harder and is more likely to make you a little breathless.

Your resting heart rate will go up, which means your heart rate will rise higher much quicker than normal.

Varicose veins

Have you noticed any varicose veins? This is due to the effect that hormones have on the veins. It softens them, so they dilate more, and this can mean that blood pressure is also a little lower. When blood pressure is lower it can lead to a feeling of faintness or lightheadedness upon standing or during exercise and is something pregnant women should monitor.

Pelvic pain

Pain in the pelvic girdle or back is incredibly common in pregnancy due to hormones as well as the huge loads of basically carrying a watermelon around. The joints in the pelvis and back become more mobile and compressed, which means that during or after exercise pain in the pubic bone, bottom, hip or back may commence. This is something women should monitor and get treatment and advice if it commences.

Feeling breathless

It will be harder to breathe due to the upward and outward shift of organs by the growing fetus, and the subsequent compression of the diaphragm.

Nausea and exhaustion

Nauseous and exhaustion is incredibly common in the first half of the pregnancy, as a result of pregnancy hormones.  For many, this means that exercise needs to be shorter and less intense.

Leaking bladder

As you’ve probably heard, urinary leaking is common in pregnancy and this is because of the softening of the pelvic floor in preparation for birth as well as the weight of the baby pushing on the bladder. It may be experienced more during exercise such as running or jumping. If it is experienced, it’s important that pelvic floor exercises are being performed daily.

Weight gain

You will, of course, gain weight and it will be distributed in new areas, making exercise such as those lying on the tummy or with weights directly in front impossible.

Core temperature

There is an increase in core temperature in pregnancy, which means during exercise it is a little harder to keep cool. It is important not to overheat during exercise due to the risk of neural tube defects at temperatures above 39 degrees.


Most exercise will be fine however please avoid hot yoga, exercising in hot pools, exercising in extreme heat or for prolonged periods where the body can’t cool off.

Exercise in pregnancy sounds like a complicated business, and this is why many people fall into the trap of thinking it’s simply too hard. But it’s really not. I urge all women to follow these very simple recommendations to ensure they are exercising in a way that is not only safe but is going to create long-lasting health benefits for mother and baby.

  1. Avoid lying on your back to exercise after 17 weeks of pregnancy
  2. Avoid exercising in extremely warm temperatures, hot pools, saunas or spas due to the thermoregulation ability
  3. Monitor to ensure you are exercising at a moderate intensity. By doing this you ensure that your baby is getting enough oxygen, and you’re challenged enough to provide the health benefits.

There are two very simple ways to do this:

  1. The talk test: If you can maintain a conversation you’re doing it right!
  2. The modified Borg rating of perceived exertion is a scale that women learn to rate themselves on as exercising at the level of 12 -14 which is somewhat hard.

Other things to remember…

  1. Drink lots of water and eat enough food, especially before you exercise.
  2. Listen to your body. If you aren’t feeling great, you get pain or are exhausted your body is telling you something. These days are best as a light walk or rest days.
  3. If doing weights, keep breathing throughout the load, and do not breath-hold. Watch for the presence of visible abdominal separation under high loads or pelvic floor weakness and leaking. Seek support from a women’s health Physiotherapist if this occurs.
  4. Add pelvic floor exercises to your routine. There is strong evidence that pelvic floor muscle training during pregnancy can prevent and treat urinary incontinence after your little one arrives.
  5. Always watch for any symptoms such as bleeding, significant shortness of breath, dizziness or other adverse symptoms and seek medical support.

Finally, if you have previously been inactive then don’t fear, pregnancy is the perfect time to start!

The 2019 Canadian Pregnancy Exercise Guidelines state that previously inactive pregnant women not meeting the exercise threshold should be encouraged to do so. This should occur gradually, at a lower intensity and duration and increase as the pregnancy progresses. Please seek professional guidance if you are concerned.

Refs: The Royal Australian and New Zealand College of Obstetricians and Gynaecologists. Exercise during pregnancy 2016 Statement.

Mottola at al. 2019 Canadian guideline for physical activity throughout pregnancy. Br J Sports Med 2018; (52) 1339 – 1346

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