To crossfit or not to crossfit? What's a pregnant woman to do? Part 1

A recent article in Paleo Magazine got me thinking about crossfit and other intense workouts during pregnancy. I’ve worked in many different communities and seen all sorts of variations in how women exercise. In the busy mountain town of Canmore Alberta,  I often had a caseload of Olympic level athletes, professional climbers, mountain guides and all sorts of fit active trail runners and crossfit gals. My mission in that town was to help women learn to SLOW DOWN and scale. This community had anecdotally higher rates of IUGR (intrauterine growth restriction) and difficult births. It was my theory that some, not all, but some, babies would become malpositioned, as a result of tight pelvic floor/hip muscles that just wouldn’t release. Many mama's also had a hard time letting go and allowing their minds to ‘relax’ so their bodies be primal and labour. 


My heart goes out to all my friends in Canmore who were devastated by flooding this week. Let the light shine and bring you hope as  the massive clean up begins.

My heart goes out to all my friends in Canmore who were devastated by flooding this week. Let the light shine and bring you hope as  the massive clean up begins.

Today, I work with an urban population of ‘side-walk walkers’ and immigrant women. For many of these women, activity isn’t a valued part of their culture and they simply cannot afford the time to dedicate to exercise. Here, I see much higher rates of gestational diabetes and obesity. In this community, my mission is to get women moving.

So what’s a Paleo gal to do? Where’s the middle ground? If you’re a paleo-ista mama to be, what is the right thing to do when you are newly pregnant? Is crossfit okay? 


The honest truth is that we don’t really have any conclusive evidence to support or discourage vigorous exercise in pregnancy. Doing studies on pregnant women is unethical and as a result the AOCG and SOGC both give very vague guidelines in regards to exercise in pregnancy. The crossfit mom’s website does have a link to a study that looked at birth outcomes of 2 crossfit gals. This being said, a sample size of 2 isn’t research we can base a solid set of recommendations from. So what do we know for sure?

We know:

  • Women who stay fit and active during pregnancy are healthier, have easier labours, less chance of obstetrical complications and quicker recoveries.


  • Women who exercise report higher energy and lighter mood.


  • Women who stay active tend to not gain too much weight in pregnancy, which has been shown to increase the risk of complications.


  • Women report labour as being less painful and ‘easier’


  • So let’s start exploring this topic a bit more with some basic biology. Here’s what happens when a woman becomes pregnant.

Warning…this is about to get a bit nerdy.

Heart Rate:

As your blood plasma volume increases, the amount of blood the heart has to pump through your body, also increases. This causes a rise in your resting heart rate.


Pregnant women have a higher oxygen demand than their non-pregnant counterparts. Remember, you’re breathing for two! With mild exertion there is an increase in the number of breaths and amount of oxygen required to meet your greater demands. As exercise increases to moderate and maximal levels, however, you pregnant women do a funny thing. Your respiratory frequency and maximal oxygen consumption actually begin to decrease!  Say what?? The oxygen demand at high levels of activity (e.g. a hard WOD) appears to overwhelm the system. This may be partially due to the obstructive effect of enlarged uterus on the diaphragm making it mechanically difficult to get in deeper breaths. Theoretically, this could increase the risk of hypoxia to the baby. If done once or twice, while sprinting from a sabertooth tiger for instance, it’s likely okay, but theoretically, if done 4-5 times per week throughout the pregnancy, it could lend significant effects on your placental and fetal development.

Temperature Change:

Pregnant women are well known for being furnaces! That’s because there is a lot of metabolic activity going on inside that bountiful body. As you exercise, metabolism is further increased, resulting in higher core temperatures. Ensuring that you don’t overheat or dehydrate during exercise becomes critical in order to avoid fetal mid-line fetal defects in the first trimester and central nervous system effects in the second and third.  In my experience, mild dehydration can predispose you to uterine contractions and may put you at risk for preterm labour, not to mention make you feel terrible, so please drink up!

Musculoskeletal Change:

The chilled out hormone relaxin causes your joints and ligaments to become lax…get it… ‘relaxin’. This can predispose you to everything from tearing an ACL to misaligning your SI joints to spraining an ankle. Proper form when lifting and avoiding any sudden lateral movements becomes critical. With each subsequent pregnancy, your levels of relaxin appear to exert their effects earlier in pregnancy, so take care! Your growing belly can also send you a bit off kilter, which is why pregnant women are notorious for falling down or bumping into things. Watch your balance and your belly!

I don’t want to be an exercise ‘Debbie downer’ of sorts but let’s take a Primal approach... what a cavegirl would do?

She would:

- Walk a lot

- Lift and carry children

- Carrying water

- Prepare meals and gather berries (often while squatting)

Would they be doing pull-ups, burpees and clean and jerks? I’m not so sure of that.

Stay tuned for the second half of this two- part blog post where you'll hear 'Meg the Midwife's'   Paleo-friendly pregnancy workout tips. What do you do for exercise during pregnancy? Let me know, I'd love to hear back from you!