Running while pregnant used to be something that was mostly seen with only elite female runners.
However, as the body of research1Beetham, K. S., Giles, C., Noetel, M., Clifton, V., Jones, J. C., & Naughton, G. (2019). The effects of vigorous intensity exercise in the third trimester of pregnancy: a systematic review and meta-analysis. BMC Pregnancy and Childbirth, 19(1). https://doi.org/10.1186/s12884-019-2441-1 regarding the physical and mental health benefits of exercise during pregnancy—and specifically the safety of running during pregnancy—has grown, many everyday recreational runners are now running through their second trimester and even third trimester of pregnancy.
This isn’t to say that there aren’t challenges with maintaining an exercise routine that includes running while pregnant.
Still, for many women runners who have a healthy pregnancy, it can absolutely be possible to run while pregnant.
To learn more about the physical and mental health benefits of running while pregnant and how to safely run through each trimester of pregnancy, Marathon Handbook collaborated with midwife and prenatal run coach Acadia Gantz of Canyon Wren Coaching to put together this guest article about running while pregnant.
The Honest Truth: What ACOG and IOC Actually Say
The “running while pregnant” question gets clearer every decade as the medical guidelines update. The 2020 American College of Obstetricians and Gynecologists Committee Opinion 804 and the IOC consensus on exercise in pregnant elite athletes both deliver the same message: continued running through pregnancy is safe and beneficial for most women, with specific caveats. Below is what the current guidelines actually permit, by trimester, plus the red flags every pregnant runner should know. None of this replaces consultation with your obstetric care provider — but it gives you the framework to bring to that consultation.
1. ACOG 2020 — runners can keep running
The ACOG Committee Opinion 804 (April 2020, reaffirmed) is unambiguous: women already engaged in regular vigorous exercise can continue throughout pregnancy in the absence of contraindications2ACOG Committee Opinion 804: Physical Activity and Exercise During Pregnancy and the Postpartum Period. Obstetrics & Gynecology. 2020;135(4):e178–e188.. The 2002 advice that put many pregnant runners off — “keep heart rate below 140” — is no longer in the guidance. Modern recommendations target “moderate intensity” by perceived exertion (RPE 4–6 of 10) rather than heart-rate ceiling. Running specifically is on the recommended-activity list for women already running pre-conception.
2. Trimester 1: nausea + fatigue management
The first trimester is typically the most disruptive for running not because of risk but because of nausea, fatigue, and frequent urination. Most pregnant runners drop volume by 20–40% in T1, lower intensity to easy/conversational pace, and accept run-walk patterns when needed. The fetus is well-protected; the runner is just exhausted. Hydration and electrolyte intake matter more than usual because morning sickness can dehydrate quickly. By weeks 12–14, most pregnant runners feel meaningfully better — T1 is the rough window, not the second trimester.
3. Trimester 2: peak running window
The second trimester (14–28 weeks) is the most-tolerated running window. Nausea typically passes, the bump is manageable, and most running adjustments are minor — slightly shorter stride, easier pace, more frequent fuel and water. The IOC consensus on exercise in elite pregnant athletes notes T2 is when most elite runners maintain 60–80% of their pre-pregnancy training load3Bø K, Artal R, Barakat R, et al. Exercise and pregnancy in recreational and elite athletes: 2016/2017 evidence summary from the IOC expert group meeting. British Journal of Sports Medicine. 2016;50(10):571–589.. Practical adjustments: a supportive maternity support belt, looser clothing, route choices closer to home + bathrooms.
4. Trimester 3: walk-jog or stop running
Most pregnant runners transition to walk-jog by T3, and many to walking only by weeks 32–36. The bump’s mass changes the runner’s centre of gravity, increases joint laxity (relaxin peaks here), and increases the energy cost of running by 10–15%. None of these is dangerous; all of them shift the work-effort ratio. The point at which running stops is individual: some runners finish T3 still doing easy 5K’s; others stop running by week 28. There’s no medal for either; the post-partum recovery is what matters more.
5. Red flags that mean stop today and call your provider
From ACOG: vaginal bleeding, regular painful contractions, amniotic fluid leakage, dyspnea (breathlessness) before exertion, dizziness, headache, chest pain, calf pain or swelling (DVT signs), or muscle weakness affecting balance. Any of these = stop running today and contact your obstetric care provider before the next run. These are rare in low-risk pregnancies but they’re not “wait and see” symptoms when they happen during exercise.
Frequently Asked Questions
Can I start running for the first time during pregnancy?
Generally no, not as your first running programme. ACOG recommends previously-sedentary women starting “moderate intensity” exercise during pregnancy — but suggests walking, swimming, stationary cycling, or low-impact aerobics rather than starting a running programme. New impact loading on tissues that haven’t adapted is the issue. Running after birth is the better starting point if you’re not a pre-pregnancy runner.
Will running cause miscarriage?
The evidence is clear: continued running by women already running pre-conception does not increase miscarriage risk in low-risk pregnancies. The fetus is well-protected by amniotic fluid, the uterine wall, and the abdominal cavity. Most miscarriages occur for chromosomal reasons unrelated to exercise. The medical literature has no association between running and pregnancy loss in low-risk runners.
Should I run a marathon while pregnant?
Most providers don’t recommend marathon-distance racing during pregnancy. The reasons are: prolonged elevated body temperature, glycogen depletion + bonking risk, dehydration, hours of pelvic floor loading, and limited bathroom access in racing logistics. Sticking to easy-paced shorter distances (5K to half marathon as steady runs, not racing) is the much safer choice. Half marathon racing is permitted by some providers in T2 for elite-level pre-pregnancy runners but discuss specifically with your obstetric provider.
What’s the best maternity running support belt?
Maternity-specific support belts (Gabrialla, FitSplint, Belly Bandit) suit most pregnant runners through T2 and T3. The function is supporting the round and broad ligaments and reducing the pulling sensation many pregnant runners feel by week 20+. Fit varies — try in-store or with a return-friendly retailer. Some pregnant runners use kinesio tape instead with a women’s-health physiotherapist showing the right placement.
When should I stop running entirely?
When running stops feeling good, when your obstetric provider asks you to, when any red flag appears, or when running is taking more from you than it’s giving you. There’s no objectively “right” gestational week to stop. Many runners stop spontaneously around weeks 28–32 because the bump makes running awkward; others continue easy-pace runs to weeks 36+. Walking, swimming, and stationary cycling are the safe alternatives once running stops feeling right. See our running postpartum guide for the return-to-running protocol after birth.
Is It Safe to Run During Pregnancy?
Despite previously held beliefs about exercise in pregnancy, we now know that exercise, including running, is not only safe . . . but beneficial!
Exercise in pregnancy has numerous benefits for your developing baby including lowering your chance of preeclampsia, gestational diabetes, and preterm delivery.
We also know that running makes us feel good! It reduces the risk of pregnancy-related anxiety, depression, and body image concerns related to weight gain and your growing belly.
The American College of Obstetricians and Gynecologists (ACOG)4The American College of Obstetricians and Gynecologists. (2019, July). Exercise During Pregnancy. Www.acog.org. https://www.acog.org/womens-health/faqs/exercise-during-pregnancy currently recommends that women with low-risk pregnancies should get 150 minutes of moderate-intensity aerobic exercise per week.
These are the same physical activity recommendations set forth by the Centers for Disease Control and Prevention (CDC)5Centers for Disease Control and Prevention. (2022). How Much Physical Activity do Adults Need? Centers for Disease Control and Prevention. for all adults, which means that the pre-pregnancy, pregnancy, and postpartum periods of your life can and should include about 30 minutes of moderate intensity cardiovascular exercise most days of the week.
Moreover, if you were running prior to getting pregnant, you should be able to continue running as long as you don’t have pregnancy complications or specific contraindications that your OB-GYN discusses with you.
In fact, studies6Kuhrt, K., Harmon, M., Hezelgrave, N. L., Seed, P. T., & Shennan, A. H. (2018). Is recreational running associated with earlier delivery and lower birth weight in women who continue to run during pregnancy? An international retrospective cohort study of running habits of 1293 female runners during pregnancy. BMJ Open Sport & Exercise Medicine, 4(1), e000296. https://doi.org/10.1136/bmjsem-2017-000296 suggest that running while pregnant may actually increase the chance of vaginal delivery vs cesarean section and does not lead to low birth weight or preterm labor.
But remember: pregnancy is unlike any other time in your life.
Many changes are taking place, and not just physically.
There are mental, emotional, work, and relationship shifts happening as well, and all of these can affect not just your running goals, but also your daily running habits.
Therefore, as with all types of physical activity, it is important to discuss running during pregnancy with your OB-GYN or other healthcare provider to make sure it is safe for you and your baby.
Running During The First Trimester
Here are the top three topics that come up when working with running during the first trimester of pregnancy:
1. Will I Overheat Running While Pregnant?
You may hear concerns about an increased core body temperature causing pregnancy complications such as neural tube defects in the baby.
Overheating is particularly a concern in the first trimester.
However, your core body temperature would need to exceed 102 degrees Fahrenheit for this to become a concern.
You are unlikely to reach this core body temperature simply from exercising unless you are doing very strenuous exercise on a hot day.7Study challenges overheating risk for pregnant women exercising in the heat. (n.d.). The University of Sydney. Retrieved March 14, 2024, from https://www.sydney.edu.au/news-opinion/news/2021/07/16/study-challenges-overheating-risk-for-pregnant-women-exercising-.html
However, it is still smart to avoid running in the heat of the day.
You should wear loose-fitting clothing, stay well hydrated, and stop or slow down if you begin feeling overheated, short of breath, or lightheaded.
Note: Using a sauna or a hot tub should absolutely be avoided during pregnancy.
2. How Do I Deal With Morning Sickness Running?
For many pregnant women, the first trimester is a time of nausea, vomiting, and extreme fatigue.
While exercise can help with some of these symptoms, it is important to respect your body’s needs during this time.
Figure out what time of the day you feel best and plan your workouts for when you have the most energy and the least amount of nausea.
Be sure to eat a healthy, high-protein snack first thing in the morning (having a high-protein snack right before bed or in the middle of the night can also help with nausea!).
A handful of nuts, a cheese stick, a low-sugar protein bar, or a piece of fruit with nut butter are all good morning snack options.
If possible, try to eat something before you even sit up in the morning.
Hydration is also super important; consider sipping sports drinks instead of plain water if you are nauseous.
Try making a simple lemonade by mixing a pinch of salt, and a splash of lemon juice and maple syrup into your water. Not only will this be easier to absorb by your body, but it also provides electrolytes.
Carry a small, easy-to-digest snack, and water, on all runs, and sneak a few ginger or peppermint candies into your pocket or sports bra in case nausea strikes on the run!
3. How Can I Run If I’m So Tired?
Do not feel guilty for choosing to nap instead of going for a run, your body is busy making a human and you need rest!
A good rule of thumb is to lace up your running shoes, get out the door, and commit to running or walking as a warm-up for 10 minutes.
If you still feel exhausted, go home and nap.
If you feel energized, then continue your run or walk.
Intervals with running and walking are also a great choice for running while pregnant in the first trimester when your energy levels are much lower than normal.
Focus on effort level or heart rate to guide your workouts rather than worrying about pace.
Avoid caffeine or other stimulants, as they can affect the placental blood flow and potentially restrict your baby’s growth. (One small cup of coffee or tea a day is ok.)
Running During The Second Trimester – 3 Things To Consider
1. Consider Your Nutritional Needs
Your nutritional needs grow as the baby grows.
Most pregnant women need an additional 300 calories during the second and third trimesters.
However, this is not an excuse to pile on the ice cream!
Choosing healthy and nutritious foods is even more important in pregnancy to promote your own health and well-being as well as that of your baby.
Pregnant runners need to be even more mindful of fueling before and after running, and eating at regular intervals throughout the day.
Focus on a balance of protein, fresh fruits and vegetables, and healthy fats.
(Of course, the occasional treat is important, too, but try to avoid eating high-sugar right before bed to prevent blood sugar spikes overnight.)
2. Take Advantage Of Feeling Better
Many pregnant people refer to the second trimester as the “honeymoon phase” or as their favorite part of pregnancy.
For many people, nausea and vomiting have subsided and energy levels are much higher than in the first trimester.
And while your baby bump may be noticeable, it is not as big as it will be in the third trimester as you get closer to your due date.
This means that you might not yet have the lower back pain, pelvic pain, pelvic floor pressure, and chest pain due to the extra weight and pressure in the abdomen and the enlargement of the breasts that many pregnant women experience in the third trimester once your baby is getting closer to their birth weight.
If this “honeymoon phase” applies to you, take advantage of feeling good running during the second trimester of pregnancy.
If you want to run in a race during pregnancy, now is a good time to find one, or simply enjoy the way it feels to run with your baby on board.
If you do plan on running a race while pregnant, remember that even in a competitive setting, it is important to respect your body and your baby and not push past feeling good.
3. Be Aware of the Effects Of The Relaxation Hormone On Your Body
As your pregnancy progresses past the first trimester and into the second trimester, your body starts producing more of the hormone relaxin.
Relaxin8Pregnancy and pelvic floor health. (n.d.). Mayo Clinic Health System. https://www.mayoclinichealthsystem.org/hometown-health/speaking-of-health/pregnancy-and-pelvic-floor-health#:~:text=The%20placenta%20secretes%20the%20hormone is aptly named as it helps your joints and ligaments around the hips and pelvis, as well as the cervix, “relax” in preparation for birth.
Relaxin can increase the risk of pelvic floor pain and general instability in the hips and pelvis, and even other joints in the body.
It is important to pay attention to your posture and avoid overstretching your muscles and joints, particularly if your exercise program includes activities such as strength training and yoga.
While you should still cool down after your running workouts, make sure that you are not pushing the range of motion on any post-run stretching you might do.
Relaxin is also responsible for GI distress that can appear in pregnancy such as constipation, diarrhea, and heartburn. Your midwife or doctor should have suggestions to help relieve some of these uncomfortable pregnancy side effects.
Running During The Third Trimester – 3 Things To Consider
1. Your Body Feels So Different!
The third trimester is when your belly has really “popped.”
Some runners find the growing belly to be exciting and others can find it uncomfortable both mentally and physically.
It is important to acknowledge all your feelings about your changing body and know that they are all valid!
As your uterus and growing baby are getting bigger, your blood volume is also expanding, and your breasts are changing in preparation for breastfeeding.
Here, a helpful tip for running during pregnancy is to wear a belly band and get a more supportive sports bra to provide extra compression and support against excessive bouncing with the impact of running.
2. Why Is Running Hard In the Third Trimester?
All of the changes your body is going through can lead to you feeling heavier and slower, and that running is suddenly much harder, and that’s totally normal and totally ok!
Your body may no longer be up to vigorous intensity exercise during the third trimester, even if your fitness level is still great.
Plus, many pregnant women, even healthy pregnant runners, are more prone to high blood pressure during the third trimester, and your center of gravity changes with each passing week as your baby is rapidly growing.
For these reasons, the third trimester is a great time to shift toward more walking or walk/run intervals.
Continuing to get outside and move your body–even if it is less running than you were during the first and second trimesters–has the same health benefits for you and your baby without the increased stress on your body.
Swimming, Tai Chi, low-intensity elliptical machine workouts, deep water running or walking, and prenatal yoga are also great options for third-trimester exercise.
3. Use Running to Prepare for Birth
Have you ever heard of birth being compared to a marathon?
Well, there is a reason for that!
Giving birth takes mental and physical strength and resilience, and who would be better prepared for that than a runner?!
Not only does running while pregnant give you the physical strength and stamina for giving birth, but it’s also a great time to practice positive self-talk, pick your favorite birth mantras, meditate, or make a relaxing playlist.
As a bonus, the snacks you use to fuel long runs are also the best type of snacks to have on hand for labor!
Running While Pregnant – Advice from Our Pregnancy Running Expert, Acadia:
Running during pregnancy is generally regarded as a safe activity for people with a low-risk pregnancy.
However, pregnancy is not a time to push past your body’s early warning signals.
Take your pregnancy one day at a time and don’t get discouraged if there are days that you don’t feel like running, switch to a walk, or go home and nap and try again the next day.
Moving your body in any way that feels good has great benefits for you and your growing baby.
After your little one has been welcomed to the world and you receive the clearance to start to exercise, check out our tips for postpartum running here!
1 Comment
I spoke with my ob-gyn and they said as long as I've been running all my life, it's perfectly fine to continue to do so. That was about the extent of it. Thank you so much, this is such great information.
-Leeleesana Carneiro