A lot has been learned in just the past few years about what exercise is safe for pregnant women—and how much. For the longest time, it was believed that running while pregnant could hurt the baby or even cause a miscarriage. And just thinking about if you can run a marathon while pregnant was out of the question.
But the truth is, you can run a marathon while pregnant. (In fact, one of my athletes qualified for Boston while pregnant. You can read her reflections on the process on my Instagram here.) I didn’t personally run a marathon while pregnant (though I did run double-digit long runs) but I have coached pregnant marathoners and had friends run marathons pregnant.
Still, there are a lot of fears and reservations. The purpose of this post is to respond to those fears with available facts. Because, if you decide to run a marathon while pregnant you may find that it makes you even more thankful for what your body can do. You may become a better listener to your body and a better runner.
You may also find that you never want to do it again! Every pregnancy (and every marathon, for that matter) is different.
So, let’s get you armed with the facts so you can decide to go for it or opt to wait until after you have your babe. In this article, I talk with experts and dive into the research to answer questions such as:
- Can I run a marathon while pregnant?
- Who can run a marathon while pregnant?
- Who shouldn’t run a marathon while pregnant?
- What are signs you should stop running while pregnant?
- What does the research say about training for a marathon while pregnant
- Considerations for training for a marathon in the first, second, and third trimester
Can I run a marathon while pregnant?
Yes, you can run a marathon while pregnant. It is safe to run a marathon while pregnant if your body is used to running long distances and you have no complications or high risks with your pregnancy.
As pelvic floor physical therapist Dr. Carrie Pagliano puts it: “If you’re an experienced marathoner and find out you’re pregnant, having a good sense reframing goals including understanding your vitals, you can run a marathon while pregnant.”
There is no evidence that finds running long distances while pregnant can hurt your baby or your health—as long as you do not run with an elevated heart rate (above 90 percent of your max heart rate) for an extended period of time.
Related: Baby Benefits While Running Pregnant
In fact, studies show increased health benefits for mom and baby in pregnant women who exercise. A 2011 study showed an improvement in fetal development including increased attentiveness, more lean muscle mass, heightened discipline, and increased neurodevelopment.
You can read more about the benefits of moms who exercise here.
But, running a marathon while pregnant isn’t for everyone. Here are guidelines on who can and who shouldn’t run a marathon while pregnant:
Who can run a marathon while pregnant?
A pregnant woman can train for a marathon if she:
- Ran a marathon recently
- Is accustomed to marathon training when they became pregnant
- Has her OB/GYN’s clearance
- Doesn’t have any complications or a high-risk pregnancy
- Is running the marathon for fun, not a time goal
- Is able to keep their heart rate below 90% of their max heart rate
- Stay on top of the pelvic floor, glute, hips, and core exercises
- Listens to her body and knows when to pull back or change the goal, and
- Will be diligent about eating and drinking enough
Who shouldn’t run a marathon while pregnant?
A pregnant woman should not train for a marathon if she:
- Has not run a marathon before or recently
- Has not been running marathon training distances (no solid base)
- Does not have a doctor’s clearance
- Has complications or a high-risk pregnancy including preeclampsia, placenta previa after 26 weeks, and heart or lung disease, for example
- Is not flexible in changing the goal to fit her body’s needs
- Ignores pain out of stubbornness
- May withhold food to avoid weight gain
- Will not be diligent about physical therapy and pelvic floor exercises, and
- Is trying to run a marathon PR.
What are signs you should stop running while pregnant?
A pregnant woman should stop running or scale back if she experiences any of the following:
- Vaginal bleeding
- Bladder leakage
- Painful contractions
- Pressure or pelvic pain
- Struggling to recover in between runs
- Round ligament pain
- Knee, feet, back, etc. pain
- Low energy
This is not an exhaustive list. Discuss any symptoms with your OB, run coach, and pelvic floor specialist.
What the research says about training for a marathon while pregnant:
- Running doesn’t impact the baby’s heart rate if the mom’s heart rate is kept below 90 percent of the max.
- Elite athletes get pregnant, train, and have healthy pregnancies and babies.
- The risk of overheating while running is highest in the first trimester and is low. Avoid running in hot weather conditions.
- The baby’s blood supply via the umbilical cord is minimally affected by running long distances or at a higher intensity. The body is smart and works to protect the fetus.
- Pregnant women need more water for things like increased blood supply and amniotic fluid so be sure to stay hydrated and not feel thirsty!
- Your gait will change as you progress in your pregnancy with an anterior pelvic tilt, wider stance, and longer ground contact. Counteracting this will strength work in your core, hips, and glutes. I recommend ReCORE’s program for prenatal runners.
- There is no evidence that training for a marathon while pregnant will cause preterm labor, miscarriage, or low birth weight.
- Running while pregnant could cause pelvic floor weakening but if it is accompanied by strength exercises (and a maternity support belt), it could actually make the area stronger.
10 Considerations for running a marathon while pregnant:
Training for a marathon while pregnant will not look the same as training for a marathon while not pregnant, especially if you are a more advanced runner. These tips will help you train for your marathon pregnant more safely.
- Run by feel. If you are pregnant running a marathon, this is not the time to go for a personal best or even a specific marathon time goal. There is no way to predict how you will feel as your pregnancy progresses, so run by intuition. If your schedule says 8 miles and you’ve exhausted by 6 miles, call it a day.
- Run a base phase. For a lot of pregnant runners, marathon training looks like a big base phase with lots of easy miles. The focus turns to endurance over speed and endurance.
- Run hills. If you are training for a marathon and want to maintain some speed work, hills are a great way to improve the overall running economy without less of an impact. If you do hill workouts, ensure they aren’t overly strenuous. Run shorter intervals with longer recovery.
- Increase recovery. Speaking of recovery, there should be more recovery in between long runs and any workouts you do. An extra day off should be considered as well as a longer training week such as a 10-day schedule rather than 7 days.
Related: 12 Genius Stroller Running Tips
- Scale effort and volume. Any intensity or volume should be scaled to meet the needs of your body. Tempo runs should be run at marathon effort versus threshold effort. Intervals should be run at threshold versus VO2 max. Volume of the workouts should be reduced such as 15-minute tempo rather than a 20-minute tempo. Again, ensure longer recover in between intervals and sessions.
- Don’t run in extreme conditions. Don’t run in overall hot or really slick conditions. Become a fair-weather runner or opt for the treadmill when the weather doesn’t cooperate with your running schedule.
- Pay attention to heart rate. Aim to keep your heart rate below 90 percent of your max heart rate. Consider training by the rate of perceived exertion (RPE) or heart rate over pace. RPE factors in your heart, breath, and sweat rate; fatigue; and overall feel.
Related: What is RPE in Running?
- Focus on nutrition and hydration. There is an increased need for calories and hydration with electrolytes as your pregnancy progresses. You’ll need about 300 more extra calories in the second trimester and 450 to 500 in the third. For hydration, aim to have your urine be pale in color.
9. Get a maternity support belt. As your belly grows, your pelvic area, bladder, and back will need more support. Consider getting a maternity support belt such as ReCore’s FITSplint. Also, consider getting fitted for new running shoes if you believe your feet have grown which is common in pregnancy.
- See a Pelvic Floor Physical Therapist. It’s never too early or late to strengthen your pelvic floor and core. See a PFPT and routinely do the exercises they recommend to keep your hips, glutes, pelvic floor, and core strong.
This will help with your return to running postpartum too. (Check out my free Postpartum Running Plan).
Can I run a marathon in my first trimester?
Yes, you can run a marathon in your first trimester. Your running may feel pretty similar to running without being pregnant (especially if you do not have morning sickness or low energy).
Just remember this is not the time to go for personal best running times and avoid running in high heat.
Can I run a marathon in my second trimester?
Yes, you can run a marathon in your second trimester. You may feel great running in your second trimester, in fact. Again, don’t push into your upper limits of effort or heart rate. Also, consider wearing an exercise belly band.
Can I run a marathon in my third trimester?
Yes, you can run a marathon in your third trimester! Know that your pace and time may be much slower than what you are able to run not pregnant. Focus on covering the distance and feeling good, rather than time or pace! Keep up your core and pelvic floor exercises!
I coach pregnant and postpartum runners and would love to help you with your running goals! Check out my coaching services for more information. Also, be sure to check out my free training plans:
- Free Postpartum Training Plan
- Free After a Break Training Plan
- Free 5k Training Plans
- Free 10k Training Plans
- Free Half Marathon Training Plans
- Free Marathon Training Plans
- Free Strength Training Plan