Pregnancy 101: Exercising Safely

Monday, May 11, 2020

When we are talking about exercising during pregnancy there are two main things to consider – Could this exercise harm my baby? Or, could this exercise harm me, the mother?

Could this exercise harm my baby?

  1. The Cardiovascular System

During pregnancy there is an increased load on the cardiovascular system: The mother's heart must now pump blood (along with oxygen) around both her and the baby's bodies. This may make her short of breath at lower loads than previous and reduce her blood pressure leading to an increased chance of her fainting and injuring herself and/or her unborn baby.
Looking after the baby's health means that we want to ensure an adequate supply of blood and oxygen to both the baby and mother whilst she exercises. Even from the first trimester, consider exercising at a level that you can still hold a conversation: also known as ‘The Talk Test' or the ability to talk in full sentences through-out your workout.
But what if you are a high-level athlete? If you want or need to train at a high intensity during your pregnancy you need to be closely monitored during exercise to ensure the safety of your baby. Studies have shown that foetal heart rate was compromised when the mother reached over 90% of her maximum heart rate.

  1. Supine Hypotension

Laying flat on your back – or ‘supine' can become an issue in the later half of pregnancy. After 18 weeks, the combined weight of the baby, uterus, placenta and fluid can compress the blood vessels travelling through your abdomen and reduce the flow of blood from the lower limbs back to the heart. This is what we call ‘Supine Hypotension' or reduced blood pressure when laying flat on your back and can cause dizziness and light-headedness in the mother. This indicates that the baby isn't getting enough blood or oxygen and you should avoid exercising in this position, especially exercise that increases your heart rate.
This doesn't mean you can't exercise, just that you may need to modify exercises or positions in order to exercise safely. For example, instead of laying on the floor doing a bridge/pelvic lift exercise, you can reduce the pressure on your blood vessels/heart by having your upper back resting on a swiss ball so that your body angles downwards instead of flat. You may also have to change your sleeping position to sleep on your side rather than your back.

  1. Decreased uterine blood flow during Valsalva (strain)

The ‘Valsalva Maneuver” is often used to aid core/spinal stability when lifting heavy weights and involves holding your breath while you strain or bare down. This effectively increases the intra-abdominal pressure and helps brace your back while you lift. However, after 18 weeks of pregnancy, this can reduce uterine blood flow and should be avoided.

  1. Over heating:

During pregnancy the mothers core temperature increases by 1-1.5 degrees. Increases of more than 1.5 degrees may be dangerous to the unborn baby, especially in the first trimester.
In order to minimize or avoid overheating, make sure you are exercising in a well ventilated area and take regular breaks to allow your temperature to return to normal if you start to feel too hot. Avoid Bikram yoga (also known as Hot Yoga) and stay out of the spa or sauna. You can use a hydrotherapy pool to exercise at a moderate intensity, but make sure the temperature of the pool is 33 degrees or lower.

  1. Force to the Abdomen:

The unborn baby is relatively protected by the mother's pelvic brim until about it reaches between 15-20 weeks (depends on the way each woman carries). After this time, the size of the baby means that it sits above the rim of the pelvis and direct force or trauma to the abdomen can put the baby at risk. After 18 weeks, it is important to consider risk factors or whether the activity is appropriate to do, when considering participating in contact sport, or sports/activities where there could be a risk of falling or being hit by a ball or racket.

Could this exercise harm me?

The next thing to take into consideration when exercising, is whether the exercise could harm the mother. Hormonal changes, fluid retention, weight of the baby and postural changes can all impact you while you exercise and may increase your risk of injury.

  1. The Pelvic Floor

There is greater load on the pelvic floor during pregnancy due to your growing baby. Doing exercise that further increases this pressure can overload this system and may lead to stress incontinence both during and after pregnancy.
Hormonal changes, especially in the later stages of pregnancy are designed to soften the strong ligaments of the pelvis to give more flexibility to the pelvic tissues allowing for vaginal birth. These are normal changes that occur during pregnancy and are worth keeping in mind as you plan your exercise regimen.

  1. Abdominal muscles

It is normal for abdominal muscles to separate at the Linea Alba during pregnancy. 100% of women who carry a baby past 35 weeks will experience this to some degree. This natural separation can be exacerbated by certain exercises if pressure is not controlled properly.

  1. Joint pain and discomfort:

It is common to experience various aches and pains during pregnancy as your body posture and centre of gravity changes as your baby grows. Pelvic girdle pain can occur due to the softening of pelvic ligaments as your body releases hormones to get ready for birth. Low back pain is common due to physical changes and Carpal Tunnel is a common condition caused by fluid retention and hormonal changes during pregnancy. All these can be influenced either positively or negatively by the exercises you do.

In Summary, in this series of pregnancy 101 blogs I have discussed the importance of regular exercise during pregnancy and things to look out for to keep both yourself and your baby safe while you do so. It is a good idea to talk to your healthcare team about your planned exercise regimen to make sure you minimise your risk factors. If you have any questions, please get in touch!

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