Running While Pregnant: What's Different in the First Trimester?


Now that I’m almost 12 weeks into my first pregnancy (the second trimester is just around the corner!), I thought I’d share how running is going while pregnant. I’m not looking pregnant to other people yet, but I can defiantly tell my body is going through some changes and it’s having an effect on my running.

The biggest way I’ve noticed pregnancy affecting my running (and my life) in the first trimester is that I’m tired all the time. Which is to be expected because I’m growing a tiny human inside of me but I never realized how tired I’d actually be! And it’s not just at night, but it’s all-day tiredness that has me taking naps whenever I can and being easier on my body. There are days where I still run since it helps give me some more energy but I might decide to do a shorter run instead. And I cut out speedwork not too long after finding out I was pregnant because I didn’t have the energy for it anymore.


Now that I’m getting closer to the second trimester, I have added some speedwork back in via Zwift (the tempo runs on there are great!) but I’m still cutting some of my runs shorter because I don’t have the energy. This usually happens on my Sunday runs where I’m aiming for six miles but some days realize about mile three that I’m starting to feel tired and cut it short. It’s frustrating not to do the mileage that I used to do (I ran eight miles after getting my positive pregnancy test and that hasn’t happened again) but I’m hoping that as I get into the second trimester I’ll get my mileage back up a little.


My speed has also slowed down since finding out I was pregnant. My average pace went from 9:27 in November to 10:07 in December and is now around 10:30 so far in January. I’m finding that my pace run to run can really vary just depending on how I’m feeling that day and where I’m running. But I’m finding that I am taking walking breaks when I’m running outside, especially when going up hills. At this point, I’m slowing down more because I don’t have the energy to go faster (or because I’m starting to feel a little out of breath) and not because it feels uncomfortable to go faster. And I have done some short bursts of speed during tempo runs on Zwift but I can tell my body doesn’t have the power to run as fast for distance like I used to be able to.

The last thing I’ve really noticed changing with running in the first trimester is that I’m getting sore much more than I used to. I’ve always struggled with making foam rolling and stretching part of my post-run routine but I never felt as sore if I skipped it as I do now. I am trying really hard to just do some simple stretches post run or take a couple minutes to foam roll after a run to try and get ahead of the soreness. I’ve been wearing my compression socks more often and taking more epsom salt baths. Both things I haven’t been doing regularly since I was marathon training.

So far, running during pregnancy is treating me pretty well! Overall, I’m just having to listen to my body more, take it easy at points and make sure I’m treating myself well post-run. I’m excited to keep on running in the second trimester, where I’m hoping that I’ll have some more energy (even as I start looking obviously pregnant) and that we’ll get better weather so I can run outside more!

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