First Trimester Workout Guide | PreNatal Fitness Routine

how to workout in the first trimester

This prenatal fitness guide is for the millennial ( or non millennial) mom who is used to taking classes like Barry’s Bootcamp or SoulCycle, running marathons, triathlons, CrossFit and pushing your body to it’s limit. It is not for newly pregnant fitness beginners.

When I first got pregnant with Tommy, I searched the internet for assurance that continuing to work out as I was, was safe and found comfort only in random blog posts. I decided to create this prenatal fitness guide for those of you like me looking for some guidelines for people who are used to working out hard and hearing that you need to keep your heart rate below 140 feels too restricting. 

The First Trimester

While technically most people do not know they are pregnant the first 4 weeks, many experience quicker breathlessness as a first sign of pregnancy right around 3-4 weeks even before a test can confirm.

When it comes to workouts, you can continue doing what you have been doing. From crossfit, spin class, bootcamp to marathon training, as long as you are not a high risk pregnancy, you can keep on doing your favorite classes or programs.

For my first, I had just finished the Boston Marathon when I found out I was pregnant. I continued to run and actually ran a half marathon at 29 weeks pregnant! With my second, I first noticed I was pregnant because my typical 30 minute spin classes became exponentially harder. Looking back, I don’t know how I finished the marathon in 2015. I had convinced myself that it was more difficult than I expected because of the weather but I definitely now realize it was the early hormones from pregnancy.

A few precautions:

Avoid deep twists. You can probably do these until the 2nd trimester but this is a big modification for making exercises prenatal friendly in most classes.

You likely don’t want to tell anyone you are expecting so if you are taking a class, just modify by twisting a little less at first and by 2nd trimester, avoid twisting all together.

Keep your heart rate below your maximum capacity. This might come as a no sh*t, but many prenatal fitness suggestions say to keep your heart rate below 140 which is super low for people like me (and probably you) who are used to HIIT, spin class, bootcamp, etc… A friend of mine was told to keep her heart rate below 170 bpm.

If you like hard workout classes, I recommend getting a watch with a built in heart rate monitor for safety’s sake. I like the ones that measure through the wrist.

Personally, when I got around 160/165 bpm with my first pregnancy, I couldn’t push past that point of exhaustion. I generally tried to max out at 160 bpm in spin class which was the most intense exercise I did. I still felt totally spent at that rate but it was much lower than the 178 I used to get taking class at Barry’s Bootcamp.

Above was a combination of personal experience and expert advice but in the end, you have to listen to your body. If you are used to pushing yourself, then push yourself just be aware of when you need to tap out.

To find your maximum heart rate, an easy equation is 220 minus your age.

Multiply that number by .85 and that should roughly be your maximum heart rate while exercising if you were in shape before getting pregnant.

Like I said above, I never wanted to go past 160 with my first pregnancy. It was too uncomfortable. My body naturally told me to stop. Everyone is different as is every pregnancy. If something feels uncomfortable, stop!

Also, hydration is so important now that you are expecting. Have plenty of sips throughout your class and make sure to use the bathroom before it starts to avoid having to take a pee break (which wouldn’t be the worst thing in a bootcamp class like Barry’s that has little breaks but would be challenging in a dark room like at SoulCycle.)

If you are a high risk pregnancy, please do not listen to my advice but seek the help of your doctor! If you have no reason otherwise to believe you have a normal pregnancy then continue.

What I did/do during my first trimester:

In addition to running and spinning, I also did Pilates at local body studio BTone which uses a megaformer with the Lagree Method.

SLT Lagree Pilates First Trimester Pregnancy Prenatal Pilates

I also was doing yoga pretty regularly and would take Barry’s Bootcamp on occasion since I was teaching there at the time. 

The good old days of not having any children!

With my second, I’m spinning for 30 minutes using Peloton, taking BTone still and doing my own HIIT workouts that I’ll share next week. I have a lot less time to exercise this time around for obvious reasons. 

Again, the spinning feels way more difficult than it did before I got pregnant so I’m not turning up the resistance as high and taking breaks when I need them. 

I’m also more concerned with diastasis recti the second time around and trying to really engage my core no matter what exercise I am doing. More to come on this in the second trimester but there isn’t too much to worry about here in your first trimester.

During my 6th week with Tommy, I did develop morning sickness. I like to sign up for my classes in advance so that meant skipping a few early spin classes or taking Pilates feeling like I was going to hurl because I didn’t want to get charged with a late cancel. Honestly, I felt better after taking class on the days I would wake up nauseas.

Not everyone is like this! For many people, they are so sick they cannot workout during their first trimester. In my second trimester workout post, I’ll have advice for you guys!

How To workout in the first trimester

Second time around, I’m working out less because I have a toddler to take care of and that feels like a workout by itself most days. Working out also doesn’t make me feel better necessarily at 13 weeks. If I work out too hard or too long, I feel miserable the rest of the day which is tough taking care of Tommy.

This prenatal fitness guide assumes that you were in shape before getting pregnant. If you were not, leave me a comment below and I’ll work on creating one to start with but at first, I just want to create a program that I used personally.

How To workout In the first trimester

The Plan

Aim to get 4 days of exercise in a week of at least 30 minutes. This is our goal!  

I also recommend getting an additional day of light exercise if you can fit it in like a long stroller walk with the older sibling, a walk/hike with your partner or yoga class just to move your body because I really do feel that exercise, even light, helps you feel more energized, regulates mood swings and hormones, which helps you feel better in the long run.

Monday or Day 1: Prenatal Cardio

Tuesday or Day 2: Prenatal “HIIT”

Wednesday or Day 3: REST

Thursday or Day 4: Prenatal Cardio 

Friday or Day 5: Prenatal Strength

Saturday or Day 6: REST


If you hate cardio, then feel free to do 2 days a week of Prenatal HIIT and 2 days of Prenatal Strength.

Prenatal Cardio

Choose from one of the following:

  • Indoor Spinning
  • Running (If you are a runner and have been running)
  • Walking
  • Swimming
  • Elliptical
  • Rowing

You have options depending on what brings you joy with this one! Right now, I’m loving indoor spinning because it is the dead of winter. If you take a class, likely it is a mix of intervals, climbs and sprints which is great so that your heart rate can come down during periods of recovery.

If you are not taking a class, try using one of the classes programmed on the bike or elliptical that alternates between heavy resistance and slower pedal strokes with lighter resistance and quicker cadence for 30 minutes.

As for walking, aim for a brisk pace and maybe even try a few hill intervals. In my guide that is coming later on, I’m going to add specific workouts.

Running is great if you enjoy doing it and are not too uncomfortable yet. A good bra can make all the difference. My favorite is the Moving Comfort Juno Bra. Try alternating between a run and walk. Warm up for 5 minutes at an easy pace or walk. Next run for 3 minutes followed by a walk for 1 minute, continue this 3:1 interval ratio for 5 rounds and then cool down with a slow jog or walk for 5 minutes. As you progress, these intervals will get shorter.

Swimming is amazing for later in pregnancy but if it’s something you currently enjoy, have at it! I like to alternate between free style, breast stroke, and flutter kicks using a kick board. If you are looking for a structured swim workout, check out this four week triathlon training program to inspiration.

If you are looking for a rowing workout, here are a couple favorites.

My Prenatal HIIT and Prenatal Strength workouts will be coming in the next week or so but as an alternative until then or even after you can always do your favorite classes at the gym like Pilates for Strength or a Bootcamp for HIIT. The strength classes will have your heart rate 145 or below, and the HIIT will raise it up a bit before allowing you to catch your breath but is not as intense as pre-pregnancy!

This is a long post and I wanted to break stuff up and also get you excited for my guide that I’m working on.


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