Exercising during pregnancy: Answering your common concerns
When you’re ready and want to start exercising in pregnancy, there can be a host of information out that which supports it, but also conflicting advice that might make it seem like the wrong thing to do. “What is safe to do?” or “what can I lift?” are common queries I get asked. I will explain in more detail some of the common pregnancy exercise concerns and give pregnant mothers freedom to make their own choices, without fear, based on current research at the time of writing this blog.
Why is exercise during pregnancy recommended? What are the limitations?
There will always be room for more research in the space of pregnancy and postpartum exercise, however it is one of the reasons I love working with this niche as there is so much more understanding around what we can do in pregnancy.
So often when there is limited research in a space the simple answer is “its dangerous” or “avoid it”, when really the research indicates there is so much we can do.
“What if our message to expectant mothers was more about strength and empowerment in pregnancy, rather than de-conditioning and weakness?”
Research has come so far in the last few years. So much so that some of earliest blogs I wrote are now completely outdated in their research (and they’ve been removed!). Yet with all this empowering new research for pregnant mothers, it still comes with scaremongering and comments like “you’re a basket of eggs, be careful” when it comes to exercising. So what if our message to expectant mothers more about strength and empowerment in pregnancy, rather than de-conditioning and weakness?
Both the HSE & NHS recommend at least 150 minutes of exercise per week when pregnant. When broken down further equates to roughly 30 minutes over 5 days. Further to this, the NHS advise two strength sessions per week.
With this advice as a baseline, lets address some of the many (but not exhaustive list) of why it’s beneficial to be active in pregnancy.
The benefits of staying active during pregnancy
Here are a few reasons why exercise can benefit the mother during pregnancy. Not all of these are guaranteed, but it can help with…
Reducing excess fat stores
Reducing pelvic girdle pain (PGP) and other common aches and pains
Improving overall strength
Decreasing risk of gestational diabetes, hypertension & preeclampsia
Reducing constipation and bloating
Improving posture
Regulating hormones & sleep
Although exercise has no impact on birth outcome (vaginal or cesarean) as outcome can be down to many other factors outside of the realm of exercise, but can aid with the mothers endurance and stamina during labour & birth
Aiding with postnatal recovery
Prenatal exercise and it’s effects on postpartum mental health 2024 Hicks et al. study indicated that higher and lower levels of physical activity during pregnancy were consistently associated with improved postpartum mental health outcomes, including reduced depressive symptoms, lower anxiety, and enhanced overall well-being.
Exercise doesn’t just benefit mum, but it can have the following positive affect on baby too
Mother's physical activity during pregnancy and newborn's brain cortical development 2023 Na et al. found that a higher maternal physical activity level is associated with greater neonatal brain cortical thickness, presumably indicating better cortical development in the baby
Increase blood flow to baby & placenta
Maternal Exercise & Cognitive Functions of the Offspring 2015 Robinson et al. found that exercise during pregnancy can improve cognitive function in the offspring. Improving learning, memory and decreased anxiety-like behaviours.
So now we know a few reasons why exercise can be so beneficial, lets move onto some of the common misconceptions, latest research and exercise guidelines on the back of this.
Common Questions with Pregnancy & Exercise
1: How heavy can you lift in pregnancy?
While lifting weights might not be advisable for everyone during pregnancy (for example, if you have contraindications towards this type of exercise) however strength training with appropriate weights, good technique and breath work can be hugely beneficial in pregnancy. Lifting weights can not only strengthen muscles but also avoid de-conditioning of the body.
Latest Research: Impact of heavy resistance training on pregnancy and postpartum health outcomes 2023 Prevett et al. is one of the latest studies in this field where 679 pregnant individuals who partook in Crossfit or heavy lifting in pregnancy. Those involved lifted up to at least 80% of their one-repetition maximum (RPM) during pregnancy - so pretty heavy!
Over half of the participant (66%) reported no complications during pregnancy or delivery and 57% reported urinary incontinence following pregnancy.
Interestingly, the participants who maintained pre-pregnancy training levels until delivery also reported significantly less reproductive complications than those who ceased training levels prior to delivery and 89% of the participants returned to lifting after birth.
The conclusions of this study found that pregnant individuals who engaged in heavy resistance training had typical perinatal and pelvic floor health outcomes expected with pregnancy and delivery. In other words, their typical post-birth outcomes weren’t worse or better because they lifted; they are as expected.
What we know now & current advice: If you choose to lift weights and have no contraindications to exercise, it’s important to consider your technique, breath work and ability to manage core pressure and load well - you can learn more about core & pressure management in my free eGuide - Exercising in your pregnancy.
How much you lift is highly individualised. Lifting heavy requires a lot of tension, strength, pressure and control from multiple interacting systems within the body. So lifting in pregnancy will be different for someone who has been lifting all their life and used to this demand vs. someone who is taking up strength training for the first time in pregnancy.
If you’re starting out, focus on building up good technique and understanding core pressure management and gradually increase resistance, starting with lighter weights. You can learn more about core & pressure management in my free eGuide - Exercising in your pregnancy.
If you’re a more experienced lifter, similar advice in understanding good breath work and pressure management. Certain lifts may not have been hard when not pregnant, but think about the pressure on your core and pelvic floor as pregnancy progresses.
Things to think of when lifting weights;
‘am I straining through the movement?’
‘is my technique affected by the lift?’
‘am I breath holding to try and get pressure for the lift’?
‘can I see that core is under too much pressure by coning/doming through the midline?’
‘Do I feel heaviness in the pelvis or pelvic floor during or after certain exercises?’.
If you are answering yes to any of these, it might be that you need to lessen the load you’re lifting and/or address your core and pressure management and breath work.
Top tips:
Work with resistance that you can control through the whole exercise, from start to finish and for all of the repetitions. The last repetition performed in a set or block of exercises should be as good as the first!
Try ‘exhaling on exertion’ where you exhale through the hardest part of the exercise. For example coming up out of a squat, or pressing overhead.
You can also try exhaling through the whole movement - I found this particularly helpful for clients towards the end of pregnancy who needed more support through the whole exercise, not just exhaling through the hardest part. An example of this would be, take a 360 inhale before starting a squat and just before you begin, start exhaling and continue to do so through the whole movement before standing up again.
Work on your 360 breath work and understanding core pressure management and pelvic floor
Remember that as your pregnancy progresses, you may need to adjust load you’re lifting. There is an inevitable increase in pressure in these areas as baby grows so think about how the load may influence your ability to manage your technique, tension, core pressure and breath work.
Learning how tension, good technique, breath work, core pressure management and your pelvic floor work during pregnancy is key to a well rounded understanding of exercising while pregnancy
2. What is a safe heart rate during exercise while pregnant?
Heart rate thresholds do vary depending on fitness levels prior to and during pregnancy, and your stage in pregnancy . It will feel different to someone at 12 weeks vs. 40 weeks!
There are a lot of nuances with the statement of going ‘too high’ and really is it down to the individual. There is still so much more research to be done in this space, but here are some interesting articles which may help you decide what feels right for you.
Latest Research: The effects of vigorous intensity exercise in the third trimester of pregnancy Beetham et al. 2019 found that “vigorous intensity exercise completed into the third trimester appears to be safe for most healthy pregnancies. Further research is needed on the effects of vigorous intensity exercise in the first and second trimester, and of exercise intensity exceeding 90% of maximum heart rate”.
Building on this knowledge a few years later this stufy came out: Maternal and Fetal Cardiovascular Responses to Acute High-Intensity Interval and Moderate-Intensity Continuous Training Exercise During Pregnancy 2023 Wowdzia et al. The study included 15 pregnant women who were monitored, along with their foetuses, during 1-min bouts of high intensity exercise, followed by 1 minute of active rest, repeated 10 times over. They were working within 90% of their maximum heart rate (which can be found by taking your age x 0.7, then minus that number from 208).
Although this study has a small research group (15), it indicated that for these participants, training for short bursts within 90% of your maximum heart rate was well tolerated by both the mother and foetuses with good blood flow and oxygen to the baby.
What is a ‘high’ heart rate? To find a max heart rate, let’s use a 35 year old as an example. Aged 35 x 0.7 = 24.50 then 208-24.50 = 183.50 is the maximum heart rate. So if that person was working within 90% of this, its in and around 165 beats per minute (bpm). Now…unless you have a fitness wearable, and even then they’re not 100% accurate, its hard to gauge the exact heart rate you’re at, however its a rough indicator of what 90% looks like.
Another study which encompasses both heavy lifting AND high-intensity exercise dove further into this Maternal and fetal responses to acute high-intensity resistance exercise during pregnancy 2023 Moolyk et. al . The study included 10 healthy pregnant women and 10 healthy non-pregnant individuals. Each completed 10 repetitions of three exercises - barbell back squat, bench press and deadlift at 70%, 80% and 90% of their 10 rep max with free breathing, followed by 10 repetitions at 90% of their 10 rep max with a Valsalva manoeuvre.
Naturally the mothers heart rate increased as they performed the heavy repetitions, more so when using the Valzalva breathing pattern as it involves holding your breath, but also with free breathing. This is as expected when performing multiple repetitions of an exercise one after the other with heavy weights!
Exciting findings; maternal and foetal heart rate was monitored continuously as well as their blood flow and they found no indicators to suggest that neither mother nor baby were in distress when performing the exercises.
What we know now & current guidelines: With these exciting findings, hopefully it gives you a more well rounded view on what the current research is indicating so you can make an informed decision on how hard you push during exercise. It goes without saying, it may be that you reduce the intensity on days you may not feel like it, but on days you have the energy, the research suggests you could go that extra mile if you wanted too.
3. Will exercising harm my baby or cause me to miscarry?
Continuing or starting exercise, especially in the first trimester, have historically been a concern for both pregnant mothers and consultants when it comes to miscarriage. Miscarriage risk or ‘harming’ the baby is naturally a matter of great concern during pregnancy, so this research may help with gaining a better understanding of the effects of exercise on miscarriage risk
Latest Research: Research shows that regular, moderate exercise during pregnancy is not only safe but also beneficial for both the mother and baby. It can improve circulation, reduce pregnancy-related complications (like gestational diabetes and preeclampsia), and even aid in foetal development.
Recent research including The Influence of Physical Activity during Pregnancy on Miscarriage—Systematic Review and Meta-Analysis 2023 Baraket et al. looked at 13 pregnant mothers who had no contraindications to exercise. All participants varied in their exercise levels and intensity. Intensity levels were around moderate/50-70% of their max heart rate or, between 20-60 minutes per session, 3-7 days a week - so a completely mixed bag! It included activities such as aerobic training, strength training, yoga, pilates and pelvic floor training.
The study concluded that pregnant individuals, who had no contraindications, can exercise safely throughout pregnancy without fear of miscarriage. The ‘moderate quality’ evidence suggested there is no difference in miscarriage risk between those who exercise compared with those who do not.
What we know now & current guidelines: More research is needed and to fully investigate the risks of miscarriage in those engaging in exercise above the pregnancy guidelines specified. Earlier studies in this area had similar outcomes such as Elite athletes and pregnancy outcomes: A systematic review and meta-analysis 2021 Wowdiza et al. concluded that there were no increased rates of miscarriage, although the quality of evidence was rated as “very low” due to inconsistency and risk of bias.
There are occasions where a mother may have contraindications to exercise and have been advised by their healthcare provider to avoid exercise, such as a weak or incompetent cervix, so once again taking an informed, individualised approach is important.
There are some exercises/activities that are advised to avoid during pregnancy which may increase risk of falling and ‘bumping the bump’ such as horse riding, team sports like rugby and skiing, but also exercises like box jumps or trampolining - not to mention the pressure on the pelvic floor too! Its also not recommended to partake in activities in extreme temperatures, such as saunas, hot tubs, hot yoga and cold plunges.
Final thoughts
This blog aims to give pregnant mothers the information they need on common queries when it comes to exercise and how you can now take your own educated view on it. When starting to exercise, what you lift or the exercise you partake in, should be tailored to the individual’s fitness level, preferences, and any medical considerations so if in doubt, always consult a healthcare provider before starting an exercise routine for the first time.
Remember, if you choose to exercise in pregnancy, focus on your body’s ability to cope with the resistance you’re lifting and the intensity you’re working at, not just what the research may indicate you could push too. Can you maintain good technique through each repetition, good core pressure management and breath work? Be mindful of how it may need to be modified according to your stage in pregnancy - happy lifting!
For more information you can download my free eGuide here, listen to a podcast episode with The Baby Tribe where I speak more about the misconceptions while exercising pregnant (and postpartum) or check out on my page about pregnancy fitness:
To find out more about exercising in pregnancy, you can all have a look on my Pregnancy Fitness page
