Your guide to moving safely and confidently through pregnancy – trimester by trimester.

Pregnancy (and motherhood!) is one long, wonderful lesson in adaptation. Your body is changing week by week, and so is the way you should move it. If you’ve ever finished a workout wondering “was that actually okay for me to do?”, you are not alone, and you’re in exactly the right place.

At Centred Mums, we support women through pregnancy exercise every single day, whether that’s in our prenatal Pilates classes in St Albans or through our online programmes. Here’s a friendly, trimester-by-trimester guide to what typically changes in your body and how to modify your movement to match it.

First Trimester (Weeks 1–12): Listen More Than You Push

The first trimester is often the most deceptive one, because on the outside very little has changed – but on the inside, everything has. Hormones like relaxin and progesterone are already beginning to rise, energy levels can dip dramatically, and nausea or fatigue may make even your usual routine feel like a big ask.

What’s changing:

• Fatigue and morning sickness are common and very real
• Your abdominals are working hard to protect a rapidly developing baby
• Blood volume is increasing, which can affect stamina

What to modify:

• Give yourself permission to slow down or take rest days – this is not the time to chase personal bests
• Avoid overheating; keep workouts at a comfortable intensity and stay hydrated
• Start paying attention to your breath and pelvic floor connection now, so it becomes second nature later
• If you’re new to exercise, prenatal Pilates is a gentle, safe way to begin building strength from the ground up
• If you’re already exercising you can continue with your usual routine (unless it involves overheating in something like hot yoga) but listen to your body – if you feel like you need to take a step back then do!

Second Trimester (Weeks 13–27): The Sweet Spot — With a Few New Considerations

Many women feel their best during the second trimester – nausea eases, energy returns, and the bump is visible but not yet restrictive. It’s a great window to build strength and flexibility, but your body is quietly shifting in ways that matter for how you move.

What’s changing:

• Your growing bump shifts your centre of gravity, affecting balance and posture
•  Relaxin continues to loosen ligaments around your joints and pelvis
• The abdominal wall begins to stretch, and some women notice the first signs of abdominal separation (diastasis recti)

What to modify:

• From around 16 weeks, avoid lying flat on your back for extended periods – try semi-reclined or side-lying positions instead
• Steer clear of exercises that create excessive doming or bulging through the midline; this is where pregnancy-specific Pilates really earns its keep, teaching you how to work your core without straining it
• Be cautious with deep twisting or high-impact movements as your joints become more mobile
• Focus on pelvic floor and deep abdominal connection – this is the foundation for a smoother birth and postnatal recovery

Third Trimester (Weeks 28–40+): Preparing the Body for Birth

As your due date approaches, movement becomes less about building and more about preparing, releasing tension, and staying comfortable.

What’s changing:

• Your bump is now significantly affecting your posture, balance and breathing capacity
• The pelvic floor is under increasing pressure as baby grows and descends
• Ligament laxity is at its highest, and many women feel achy hips, backs and pelvises

What to modify:

• Prioritise pelvic floor relaxation as much as strengthening – an overly tense pelvic floor can make your birth more difficult
• Slow down; wide, controlled movements are more suitable than fast or ballistic ones
• Use props and modifications generously – this is exactly what a specialist prenatal Pilates teacher can support you with
• Keep breathing at the centre of every session; it connects you to your body and calms your nervous system ahead of birth

The Golden Rule Through Every Trimester

Whatever stage you’re at, the same principle holds true: **your body is not the same body you exercised in last month, so don’t expect it to move the same way.** Pregnancy exercise isn’t about pushing through, it’s about tuning in.

This is exactly why generic workouts don’t always serve pregnant bodies well, and why pregnancy-specific movement matters so much. At Centred Mums, every class is designed around what your body actually needs – supporting your pelvic floor, protecting your abdominal muscles, and helping you feel strong, capable and connected right through to birth and beyond.

Ready to move through your pregnancy with confidence? Explore our Pregnancy Pilates classes in St Albans or get in touch to find the right fit for you — nothing is TMI.

If you’ve followed along with Centred Mums, you’ll know that I absolutely love using the reformer and I have one in my home studio for 121 and small group classes. It’s an incredible piece of equipment, and in an individual setting it can be transformative for building strength, improving alignment, and supporting long-term movement health.

But here’s something that might surprise you:

I don’t believe mum and baby reformer classes are the right approach for postnatal exercise.

Let me explain why.

After pregnancy and birth, your body needs more than a machine based class filled with distraction —it needs specialist postnatal recovery support that targets what you really need right now.

Your deep core system, including your pelvic floor and transverse abdominals, has been lengthened and lost strength. Before jumping into complex workouts or equipment-based sessions, the priority should always be:

• Reconnecting with your breath
• Restoring pelvic floor function
• Rebuilding core strength after pregnancy
• Improving alignment and stability

This is the foundation of effective postnatal Pilates, and you simply don’t need a reformer to achieve it.

In fact, when it comes to safe postnatal workouts, simpler is often more effective. 

The Problem with Mum & Baby Reformer Classes

While mum and baby fitness classes can be a brilliant way to get moving again, I believe the reformer environment is a bit problematic at this stage of postnatal recovery.

Reformers are large, moving pieces of equipment that require focus, control, and proper technique.

When you add a baby into that space:

• Your attention is divided
• Your movement quality decreases
• The risk of unsafe situations increases

From a postnatal fitness safety perspective, this simply isn’t ideal.

I’m sure we all know how unpredictable babies can be and being next to moving equipment doesn’t create the calm, controlled environment that your postnatal recovery exercises require.

It’s Got to Be The Right Setting

Now I’m not saying “down with reformers!” 

When working 1:1, Pilates on the reformer can be an amazing tool for strength and rehabilitation, accelerating progress safely and effectively.

It’s all about using the right tool at the right time.

What Your Body Really Needs Postnatally

In the early stages after having a baby, your body benefits most from:

• Targeted postnatal Pilates exercises
• Gentle, progressive core and pelvic floor rehabilitation
• A supportive, understanding environment
• Structured guidance from a postnatal fitness specialist

This approach builds a strong foundation for everything else – whether that’s returning to the gym, running, or eventually using equipment like the reformer.

This is exactly why I created my classes at Centred Mums.

My postnatal Pilates classes are designed specifically to support:

• Pelvic floor recovery after birth
• Safe and effective core strengthening for mums
• Realistic, sustainable postnatal fitness routines
• Confidence in your body again

There’s no pressure, no rushing, and no unnecessary complexity – just expert guidance and a focus on what your body truly needs.

Ready to Start Your Postnatal Recovery?

If you’re looking for safe postnatal exercise classes, expert guidance, and a supportive community of mums, my classes at Centred Mums are here for you. 

I would also recommend getting a full postnatal check at a specialist like Herts Osteopathy or Alban Osteopathy,  where you can build on the tailored support with feedback on what is happening internally. 

Come and rebuild your strength the right way, starting from the ground up.

Diastasis recti is the separation of the abdomen muscles (aka our six pack), It’s totally normal to occur during pregnancy as our bodies have to make space for the growing baby. 

The trouble is that this separation can weaken our core and, left unchecked, this can lead to back pain and contribute to poor posture and alignment. Whether you are a new mum or seasoned parent, dealing with back pain is difficult and can cause all sorts of disruptions to life. 

 

How can I reduce my back pain?

The first step to alleviating the pain is to get to the core of the problem…our core! By ‘closing the gap’ and addressing our abdominal function, we can relieve the pressure on our spinal muscles and ensure that our back is not doing all the work. 

 

Exercises To Help Diastasis Recti

For anyone who DOES have time to exercise, here are some useful exercises to kick start your movement practice but in an ideal world I would find a local pregnancy and postnatal specialist trained by Carolyne Anthony or Jenny Burrell as there is no substitute for good teaching! Or come and work with me in my online membership! 

These exercises should only be performed after you have had clearance from your GP to exercise again. I would recommend that you also see a Women’s Health Physio before starting any exercise postnatally.

 

 

Sidelying Ribcage Rock

• Lie on your side with both arms extended forwards at chest level with the palms together
• Inhale to rock the ribcage forward while at the same time rocking the pelvis back
• Exhale to rock the ribcage back as you rock the pelvis forward
• Repeat then change sides

This is really helpful as it will mobilise the tissues around your ribcage and torso that could be causing tension that is preventing good function in your abdominals.

 

Double Knee Openings

• Lie in neutral spine with your feet together. 
• Exhale to allow your abdominals to flatten
• Draw your hip bones towards each other and open both knees out to the side – focus on keeping the pelvis still as the legs move
• Inhale to hold the legs there, exhale to connect to your abdominals again and pull the legs back together again. 
• Think of the legs being heavy and using your abdominals to pull them back to the middle.

When working in neutral spine many postnatal women benefit from a higher head position (cushion/ block) to allow the back of the ribcage to stay released into the mat whilst the lower back can maintain its neutral curve. If neutral spine is uncomfortable for you, look at the positioning of the head.

This exercise will help to connect you to your deep core muscles. 

 

Single Knee Openings

• Lie in semi-supine
• Exhale to allow your abdominals to relax then draw your sit bones, hip bones and rib cage together
• Open one leg out to the side
• Inhale and hold it
• Exhale to bring it back to parallel
• Repeat with the other leg. 

Focus on keeping the pelvis and especially the supporting leg still and releasing as the other leg moves.

 

Pelvic Tilts

• Lie on your back with your knees bent up and feet flat on the floor
• Make sure that the feet are parallel to each other and be aware of the big toe joint connecting into the floor. 
• Exhale to gently flatten your lower back so that your lower spine softens into the floor (rolling your pelvis under and thinking of bringing your pubic bone and your rib cage towards each other). 
• Inhale and release back into neutral, allowing your hip flexors to release, the pelvic floor to open. 

 

As a variation:

• Hold the pelvis in the tilt (if you can, try not to fully release on the in breath, keeping some connection)
• Exhale to connect again
• Visualising the abdominals drawing back into the middle
• Have an awareness of your pelvic floor connecting as your ribcage is softening and the pelvic floor connecting the sit bones into the inner thighs and big toe joints with every out breath. 
• Repeat the breathing 5 times.
• Release the pelvis back to the floor.

 

Postnatal Classes with Centred Mums

All of our postnatal classes can help with your abdominal separation. We have designed each class to ensure it only contains exercises that will assist your recovery, and we will always encourage you to work at your own pace and listen to your body.

When it comes to dysfunctions like Diastasis Recti, you are often warned against exercises such as sit-ups, but we will teach you that it isn’t about the exercise but about the level of control you have. If your abdominals ‘dome’ and push out when you do a sit-up, then this isn’t a good exercise for you. But plenty of people who don’t have a diastasis also dome, and it’s not a good exercise for them either.

We’re here to assure you that you don’t be scared to move and to use your body, you simply need to learn how to use it better.

With a better understanding of what your postnatal body needs, you can avoid pushing yourself into exercises and movements that won’t serve you well in the long term. And, as experts in this, we can confidently support you through making these important changes and bring you great results with our postnatal classes or our online membership!