Most pregnant runners don’t need to stop running entirely, but there are specific warning signs, medical conditions, and body changes that signal it’s time to pause or switch to lower-impact exercise. The American College of Obstetricians and Gynecologists (ACOG) encourages women who ran before pregnancy to continue during pregnancy, as long as they don’t have complications. The real question isn’t a fixed week or trimester cutoff. It’s about knowing which signals from your body and your provider mean “slow down” and which mean “stop now.”
Warning Signs That Mean Stop Immediately
Certain symptoms during or after a run require you to stop exercising right away and contact your provider. Vaginal bleeding beyond light spotting is the most clear-cut red flag. Fluid leaking from your vagina, which could indicate ruptured membranes, is another. Both of these can signal complications that make continued impact activity dangerous.
Other symptoms to watch for include chest pain or tightness, a racing heartbeat that doesn’t settle down with rest, sudden swelling or pain in one leg (particularly your calf, which could indicate a blood clot), severe headache, blurred vision or seeing spots, shortness of breath that feels out of proportion to your effort, and pain in your upper belly under your ribs on the right side. Several of these overlap with signs of preeclampsia, a serious blood pressure condition that can develop after 20 weeks. Preeclampsia sometimes comes on suddenly, and symptoms like a severe headache, vision changes, or upper belly pain alongside swelling in your face and hands warrant immediate medical attention, not just a break from running.
Conditions That Rule Out Running
Some pregnancy complications make running unsafe regardless of how you feel. These are considered absolute contraindications, meaning running (and most vigorous exercise) should be off the table entirely until your provider says otherwise:
- Placenta previa: when the placenta covers part or all of the cervix
- Preeclampsia or gestational hypertension
- Cervical insufficiency (sometimes treated with a cervical cerclage)
- Ruptured membranes (your water has broken)
- Vaginal bleeding in the second or third trimester
- Premature labor or risk of premature labor, including some multiple pregnancies
If you’ve been diagnosed with any of these, your provider has likely already discussed activity restrictions with you. But if you’re unsure whether your specific situation qualifies, ask directly whether running is still safe.
How Your Body Changes the Equation
Even without a medical complication, pregnancy creates physical changes that can make running feel progressively harder or riskier. Your body produces a hormone called relaxin throughout pregnancy, which loosens the connective tissue around your joints. This is helpful for childbirth but less helpful for high-impact activity. Studies on relaxin’s effects show it can reduce ligament integrity, particularly in the knee. Research on female athletes found that those with higher relaxin levels had more than four times the risk of a knee ligament tear compared to those with lower levels. The practical takeaway: your joints are less stable during pregnancy, and the wobbliness or discomfort you feel in your knees, hips, or pelvis isn’t imagined.
As your belly grows, your center of gravity shifts forward, which changes your running mechanics and increases the load on your lower back and pelvis. Weight gain adds impact force with every stride. In a study of competitive runners, women on average cut their running volume significantly during pregnancy and reduced intensity to about half of their pre-pregnancy effort. Many eventually switched to lower-impact exercise like swimming, cycling, or walking when running became too uncomfortable. That transition is completely normal and doesn’t represent a failure.
Pelvic Floor Symptoms to Take Seriously
Your pelvic floor bears increasing load as pregnancy progresses, and running adds to that load with every footstrike. Symptoms that suggest your pelvic floor is struggling include leaking urine when you run (or cough or sneeze), a feeling of heaviness or pressure in your pelvis, increased urgency to urinate, or difficulty controlling bowel movements. These symptoms are common during pregnancy, but they’re also signals. If running consistently triggers leaking or a dragging sensation in your pelvis, that’s your body telling you the impact is more than your pelvic floor can handle right now.
Switching to walking, swimming, or stationary cycling can let you stay active while reducing pelvic floor strain. A pelvic floor physical therapist can also assess whether targeted exercises might let you continue running longer or help you recover faster postpartum.
Monitoring Intensity While You Run
Heart rate monitoring, the go-to for most runners, becomes less reliable during pregnancy. Your resting heart rate increases, your blood volume expands, and some pregnant women show blunted heart rate responses to exercise while others respond normally. Because of this inconsistency, ACOG recommends using perceived exertion rather than a specific heart rate number.
The simplest tool is the talk test: if you can carry on a conversation while running, you’re likely at a safe intensity. If you can only get out a few words between breaths, you’re pushing too hard. On a perceived exertion scale of 6 to 20, aim for 13 to 14, which translates to “somewhat hard.” Using both perceived exertion and heart rate together gives you a more complete picture than relying on either one alone, especially if you trained at high intensities before pregnancy.
Heat is a separate concern. Maternal core temperature above 39°C (about 102.2°F) raises the risk of complications. Research suggests pregnant women can safely run for up to 35 minutes at high intensity in environments below 25°C (77°F). On hot or humid days, run indoors with air conditioning, shorten your run, and stay well hydrated. Outdoor running in cooler conditions benefits from wind helping your body shed heat.
There’s No Universal Week to Stop
Some runners maintain easy jogging into the third trimester. Others find that the second trimester is where running stops feeling good. There is no evidence-based week of pregnancy where all women should stop running. The general guideline from ACOG is that previously active women can continue vigorous activity throughout pregnancy, aiming for at least 150 minutes of moderate-intensity exercise per week spread across most days. An individual run of 20 to 30 minutes on most days meets that threshold.
What does matter is paying attention to the trends. If you’re gradually shortening your runs and slowing your pace because that’s what feels right, you’re doing exactly what the research supports. If you’re pushing through pain, pelvic pressure, or breathlessness to maintain a training schedule, that’s when problems arise. Pregnancy is a time to run by feel, not by a training plan.
Getting Back to Running After Delivery
Most protocols recommend waiting 6 to 12 weeks after delivery before returning to high-impact activity like running. That timeline isn’t arbitrary. Your pelvic floor, abdominal muscles, and connective tissue need time to recover from both pregnancy and birth. Before you start running again, you should be able to walk and perform daily activities without discomfort, and you should be able to walk briskly, jump, and do basic plyometric movements without pelvic heaviness, pressure, or leaking.
Red flags during the postpartum period that warrant a check-in with your provider before progressing include worsening vaginal bleeding, uterine or abdominal pain, or increased bleeding with activity. A pelvic floor assessment before returning to running is particularly valuable, since issues that feel minor during walking can become significant under the repeated impact of running. If symptoms like leaking or pressure return once you start, that’s a sign to scale back and build your foundation longer before adding impact again.