The Best Way To Stay Fit During Your Pregnancy • Common Purpose

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The Best Way To Stay Fit During Your Pregnancy


Words by Tiago

Published 24th February 2021

Approximately 12 Minutes Reading Time

Brief Article Overview

  • Having trained many women throughout their pregnancy (and some women through multiple pregnancies), we truly understand the unique nature of this journey. 
  • With so much content available on the subject, it’s difficult to prioritise important decisions and approach such an important life event. 
  • Regular exercise and good nutrition are vital for a healthy pregnancy.
  • Training programs and nutrition advice need to be modified for pregnancy, tailored to the individual and closely monitored throughout (ideally, with the help from experts in multiple fields).
  • The body goes through many changes throughout pregnancy, the extent of which is highly variable depending on the individual. These changes should be understood ahead of time and communicated in real-time, between both trainer and client. 
  • Pregnancy is broken down into 3 stages, known as the 1st, 2nd and 3rd trimester. Each trimester has a unique set of guidelines. This structure can also be used for training and nutrition guidance.


It’s likely that you are reading this article because you are pregnant. If this is the case, the Common Purpose team would like to wish you a huge congratulations and the best of luck for the journey ahead! If not, and you just want to learn more about physical training during pregnancy, then that’s great too. Exercise during and after pregnancy can often be fraught with trepidation, so the more that society can understand how to navigate this journey, the better we’ll all be at helping our wives, partners, sisters, friends and all the strong women in our lives throughout this precious time.

The objective of this four-part series is to help you gain clarity on how you (or someone you know) can get the most out of training and nutrition before, during and after pregnancy. There are many benefits to be gained from regular and well-considered exercise both pre and postpartum. However, there is a lot of conflicting advice out there. This, coupled with the highly unique and ever-changing nature of the journey, can lead to confusion and sometimes a bit of fear and worry too. The Common Purpose team wants to help reduce this anxiety and provide reassurance and confidence whilst training throughout pregnancy. 

A Message from Me

I’ve been a Personal Trainer for over 12 years now and I’ve worked with a large number of pregnant clients in my time. Almost every one of them has had quite a unique experience, to say the least! I’ve even worked with a few clients over multiple pregnancies and each of their pregnancies has been completely different from one another. So, with that in mind, I hope this gives you the assurance that the experience of pregnancy is going to be unique to you. I hope this empowers you to listen to your body and trust yourself when working alongside other professionals.

Information Overload

Thanks to the internet and social media there is certainly no shortage of content out there when it comes to the “best way” to approach your pregnancy. To illustrate this point, here is an overview of the huge array of information, advice and beliefs about pregnancy that we are likely to encounter in our research.

With so many different avenues of information, it’s easy to understand why things can get confusing. However, I hope this diagram gives you a sense of autonomy when it comes to making sense of all of this information. All important decisions must be informed, it’s then up to you to follow your instincts and do what’s right for you and your baby. Just make sure that you do your research with as many reputable sources as possible and try not to linger on one area more than others. It’s also important to ensure that individuals offering advice remain within their scope of practice. 

That being said, you’ll find that information changes over time. There are always studies being carried out and new conclusions being made. So, it makes sense not to hold on to one single method, especially if strong conflicting evidence starts to appear. We call this remaining “cautious, but open” throughout the pregnancy journey.

Goal Setting and Its Struggles

As previously mentioned, we’ve worked with a large number of pregnant clients over the years and each individual has their own sets of beliefs and goals. Some clients want to bounce back as quickly as possible after birth, whilst others want to maintain body composition for as long as possible. No matter what the client’s goal; we always take them seriously. However, we do ask our clients to truly evaluate their goals and use our experience to offer alternative perspectives. For example, we may encourage clients to;


“Focus your goal on getting physically prepared for the birth itself; like you would prepare yourself for a marathon or a sports event.”


We suggest this for two reasons. Firstly, the physical demand for giving birth is extremely high and we want our clients to be in the best shape possible to handle such an ordeal. Secondly, the birth of a child is one of (if not, the) most important experiences in a mother’s life and we really take this seriously! When you think of things this way, it becomes so important that the event of giving birth deserves to be at the forefront of your training priorities.

Once we have established our clients’ focus on preparing for birth, we can then start to create a training plan by conducting a “needs analysis” (determining which physical attributes are required to succeed at a given event). You’ll find that giving birth requires a blend of endurance, stamina, strength, resilience and an ability to recover well. Based on this, we can determine the training modalities that are required. We often find that there is a huge crossover with the types of exercises we prescribe for fat-loss, endurance and strength training. By looking at your pre and postnatal exercise plan in this manner, it can unlock higher levels of motivation and energy, as different micro-goals, such as body composition or performance goals, can become embedded within the macro-goal of “training for birth”.

How to Create Positive Change 

During this time you may want to try and make some positive lifestyle changes. However, we want to set realistic expectations and ensure success, as failure can be particularly demotivating during pregnancy.

Understanding how our habits work and being able to prioritise the right ones is key in this regard. Charles Duhigg (1) describes in his book “The Power of Habit”, that habits operate in ‘habit loops’ which involve three steps: 1) Trigger/Cue, 2) Action/Routine and 3) Result/Reward. 

The ‘Trigger/Cue’ is the signal that gets you to act in a certain way. It can be a certain time of day or something that you see or smell. This initiates the ‘action/routine’ which is a particular pattern of behaviour. The completion of this behaviour pattern produces a ‘Result/Reward’, which results in an emotion. Positive emotions reinforce this habit loop and negative emotions diminish them. 

An example habit loop could be at 8pm after your evening meal, you have a craving for something sweet, so you eat some chocolate, which provides satisfaction. Often, people see their habits as only the ‘Action/Routine’ part of Duhigg’s formulae and put their focus on trying to change things here. Although this is one part of the equation, as we’ve just explained, there is more to our habits than just the behaviour pattern, we need to address the cues and rewards as well. 

It can be challenging to know which habits you should try and change. However, there are arguably some more fundamental habits (what we call “big rocks”) that we at Common Purpose would advise pregnant clients to prioritise.

Applying the habit loop formulae and focusing on the ‘big rocks’ will help set you up with the best chance to make positive change. Our clients often find this process simpler than they expected and the simplicity will certainly increase the chance of success and, in turn, build motivation. 

Footnote: For more on this topic read our article Healthy Habits: The Key to Lifestyle Change.

Body Changes and What to Expect 

It’s fairly obvious that the body will change when you become pregnant. What is surprising is that the extent of these changes and how they affect your ability to participate in exercise is highly variable. Below we’ll explore this in more detail and give you an overview of what things to watch out for.

This diagram gives you a visual comparison between the cross-section of the female anatomy before conception and just before giving birth. Whilst there are many stages during pregnancy, there are some key areas of your anatomy that are going to change, which is important to know about in relation to your exercise plan.

The Stomach and the Lungs

As the pregnancy progresses, the baby, the placenta and fluids increasingly take up space inside the abdominal cavity. Because of this, the stomach will have less capacity for food and the diaphragm can ascend by as much as 5cm (as the ribcage rises and expands). As a consequence, it’s likely that the portion sizes you eat may have to reduce in size, and eating smaller and more often may be a preferred strategy. Breathlessness is also more common, and this of course can affect your ability to exercise, so you may find you’re not able to work out as hard as you’d like and feel that you get out of breath quite quickly. The diaphragm is integral to core function, so retaining its strength and endurance during and after pregnancy is very important. 

Hormonal Changes

Conception triggers a dramatic change in a woman’s hormone levels. These hormones are what drive the biological change in your body (and also how you feel too). Below is a quick overview of the main hormonal changes that we think are worth knowing about in relation to exercise, as they can affect your performance and energy levels;

  • Oestrogen and Progesterone steadily increases and can elevate by up to 30 times the normal level by the end of pregnancy. This hormone will trigger the change in tissues that lead to greater flexibility or laxity around joints and the pelvic floor.
  • Relaxin increases quickest in the first trimester and (as the name would suggest) it’s responsible for creating greater flexibility or laxity of tissues too. 
  • Thyroid and Parathyroid hormones increase quite substantially. This will affect your metabolism, but it will also regulate blood calcium levels. It’s important to ensure your calcium intake is adequate by eating a well-rounded and healthy diet consisting of calcium-rich foods like dairy and dark leafy greens. 

Posture and Associated Pain

Changes in posture during pregnancy are not as easy to predict as you may think. Some research shows that the curve of the lower (lumbar) spine increases over the course of their pregnancy whilst other research shows the direct opposite (2,3&4). As well as this, we need to consider different types of posture; from sitting to standing, walking and exercising. Finally, understanding that an increase in pregnancy hormones (in particular Relaxin) can reduce the tension of our muscles, tendons, ligaments and connective tissue (5), may affect posture. With all this in mind, I’m sure you can appreciate it’s quite a broad and complex topic! 

What we can say with some certainty, is that your posture will change and your tissues will become more flexible; but how that change will look and whether or not you’ll have pain associated with this change is quite hard to predict. It may seem frustrating that no definitive answers can be given, but you should be expectant of change and accepting of the fact that whatever happens to you along your journey is likely to be within the wide range of normal. Keeping active and moving often will give you the best chance at managing any posture-related pain, but if things get serious or go downhill rapidly, then it’s recommended that you reach out to a professional like your GP or a physiotherapist. 


“We must remind ourselves that there is a wide range for

 what is ‘normal’ during pregnancy”


 (Girls Gone Strong – Pre & Postnatal coaching certification manual) 


Metabolic Changes and Weight Gain

A woman’s basal metabolic rate (BMR – the amount of energy the body needs to function at rest) increases throughout pregnancy. How much the BMR increases vary considerably for each person. For example, in a study of over 250 women (6), the average increase in BMR was 4% in the first trimester, 10% in the second trimester and 24% in the third trimester. However, this study also showed large individual variation, with one participant showing an increase of 63.7% at week 32 of pregnancy!

Alongside the increase in BMR, there is a healthy amount of weight gain to be expected. Most doctors will record their patients’ weight throughout pregnancy to ensure that an ‘ideal’ amount of weight is being gained and the baby is growing at a healthy rate, and it’s advised that you follow your doctor’s advice here. It’s probably a good time to stop tracking bodyweight with a personal trainer but if you continue to monitor this yourself, then it’s good to know what weight gain you should expect …

  • The total recommended amount of weight gain is 11kg to 16kg. 
  • If you started your pregnancy at the lower end of the average body weight for your age and height, then it’s recommended that 12kg to 18kg is gained. 
  • If you start your pregnancy at the upper end of average, then 7kg to 12kg is advised.

A lot of this weight gain is not just the weight of the baby growing, it’s also due to an increase in blood, fluids and other tissues that develop during pregnancy. With that being said, these numbers are just guidelines and averages so it’s to be expected that some individuals may not follow these exact trends. 

The Pelvic Floor 

In conjunction with the changes in body weight and hormones, the pelvic floor also experiences significant changes, especially towards the end of the pregnancy. The downwards pressure on these deep core muscles (that sit like a hammock horizontally across the pelvis) increases as the baby grows. This, coupled with the increase of Relaxin, can lengthen and weaken the smooth muscles around the bladder. As a result, it’s common to report some incontinence, but rest assured this is totally normal. Statistics show that in early pregnancy, rates of incontinence are around 17% to 25% and can be as high as 35% to 76% in the later stages (7). Performing Kegal exercises are a great way to help maintain the strength of these muscles alongside safely performing traditional strength exercises too.  

Trimester Breakdown

Over the duration of the pregnancy, there are certain elements that need particular emphasis with regards to your exercise and nutrition, which should adapt to the way your body changes and the impact this has on you. The table below provides a detailed overview of what to watch out for and how to modify your training plan according to pre/post-natal exercise guidance provided by fitness professionals.

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Click Here to Read About Pregnancy Exercise Considerations


Disclosure: This article is not to be used as medical advice. If you are currently experiencing physical or mental health issues, please seek professional advice from a fully qualified Nutritionist, GP or Physiotherapist.



  1. Charles Duhigg “The Power of Habit”
  2. Franklin ME, Conner-Kerr T. An analysis of posture and back pain in the first and third trimesters of pregnancy. J Orthop Sports Phys Ther. 1998 Sep;28 (3):133-8
  3. Moore K, Dumas GA, Reid JG. Postural changes associated with pregnancy and their relationship with low-back pain. Clin Biomech. 1990 Aug;5(3):169-74
  4. Okanishi N, Kito N, Akiyama M, Yamamoto M. Spinal curvature and the characteristics of postural change in pregnant women. Acta Obstet Gynecol Scand. 2012 Jul;91(7):856-6
  5. Cantu RI, Grodin AJ. Myofascial Manipulation: Theory and Clinical Application. Aspen Publishers; 2001. 261 p.
  6. Forsum E, Lof M. Energy metabolism during human pregnancy. Annu Rev Nutr. 2007;27:277-92.
  7. Wijma J, Weis Potters AE, de Wolf BT, Tinga DJ, Aarnoudse JG. Anatomical functional changes in the lower urinary tract during pregnancy. BJOG. 2001 Jul;108(7):726-32