Running while pregnant: what every pregnant woman running should know

A pregnant woman running past a café still gets looks, and occasionally a stranger with opinions. The official guidance is less dramatic than the stranger. If you ran before pregnancy and your pregnancy is uncomplicated, the major guidelines say you can generally keep running, with adjustments, and with your care provider in the loop. If you didn't run before, pregnancy isn't the time to start.

This post covers what ACOG, the WHO and the NHS actually say about running while pregnant: who it's for, how hard to go, what to watch, and when to stop. Your training should flex around a pregnancy the way it flexes around anything else, which is the whole idea behind a coach that adapts when life gets in the way.

First, the rule this whole post depends on: check with your doctor, midwife or a pelvic health physiotherapist before you keep running, and again whenever something changes. Nothing below is medical advice, and none of it applies if your care provider has told you otherwise.

Pregnant woman running: can you keep going?

For most experienced runners with an uncomplicated pregnancy, yes.

ACOG's Committee Opinion 804 says women who were regular exercisers before pregnancy and who have uncomplicated, healthy pregnancies should be able to engage in high-intensity exercise programs, such as jogging and aerobics, with no adverse effects (ACOG, 2020). The WHO 2020 guidelines say women who habitually did vigorous-intensity aerobic activity or were physically active before pregnancy can continue those activities during pregnancy and the postpartum period (Bull et al., 2020).

The NHS draws the line at starting something new: it's not recommended to start a new vigorous activity in pregnancy, such as running (NHS). If you're new to running, walking, cycling or swimming are the documented options, and a women's training plan with running built in can wait until after your postpartum recovery.

Strength work still matters alongside the running. The guidelines encourage aerobic and strength-conditioning exercise before, during and after pregnancy (prenatal workouts covers the non-running side of the week), and if you're thinking about the longer arc of training, strength training for women over 40 covers the decades that follow.

How fast and how far?

The guidance doesn't give you a pace chart, a weekly mileage cap, or a heart-rate ceiling. Anyone who gives you an exact number is improvising. Here's what it does say.

Run by feel, not by heart rate

ACOG notes that heart-rate responses to exercise can be blunted in pregnancy, so ratings of perceived exertion may be a more effective way to monitor intensity than heart-rate targets. Moderate intensity is 13–14 ("somewhat hard") on the 6–20 Borg scale. The talk test is the other tool: if you can carry on a conversation, you're likely not overexerting yourself (ACOG, 2020).

That's convenient, because it's also how easy running works for everyone else. Your easy pace will drift slower. That's not lost fitness to chase. It's the run feeling the way it's supposed to.

Harder sessions

ACOG says an upper level of safe exercise intensity hasn't been established. It describes vigorous-intensity exercise into the third trimester as appearing safe for most healthy pregnancies, while saying more research is needed on vigorous exercise in the first and second trimesters and on intensity above 90% of maximum heart rate. Competitive athletes, it says, need frequent and close supervision (ACOG, 2020).

Translation: intervals and tempo runs aren't automatically off the table for an experienced runner, but they're a conversation with your care provider, not a decision to make from a race calendar.

Long runs

ACOG notes that high-intensity or prolonged exercise beyond 45 minutes can lead to low blood sugar, so eat enough beforehand or limit the intensity or length of the session. The NHS says not to exercise on an empty stomach, as it could make you faint. Fasted long runs are out.

Heat, hydration and terrain

Heat. ACOG advises staying well hydrated, wearing loose-fitting clothing, and avoiding high heat and humidity, particularly in the first trimester. Prolonged exercise should happen in a thermoneutral or air-conditioned environment. Summer midday runs are the obvious one to move: go early, go on a treadmill, or go shorter.

Hydration. Same source: stay well hydrated. Plan your route around water, or carry it.

Falls. ACOG says activities with a high risk of abdominal trauma or imbalance should be avoided, and the NHS names sports with a risk of falling or bumping your tummy. That's a reason to think about technical trails, icy roads and crowded race starts, especially as your balance and center of gravity shift.

Altitude. ACOG notes women living at sea level tolerated physical activity up to 6,000 feet, though more research is needed.

Running while pregnant, trimester by trimester

The guidance isn't written trimester by trimester, but a few points land at different times.

That last line is the honest one. Many runners find a point where running stops feeling good and walking, cycling or swimming takes over. The NHS mentions that swimming can relieve pressure on muscles and joints. Swapping isn't quitting. It's still the 150 minutes a week of moderate activity the WHO and the NHS recommend.

Warning signs: stop running and get help

ACOG's Box 3, "Warning Signs to Discontinue Exercise While Pregnant", word for word (ACOG, 2020):

• ›"Vaginal bleeding"
• ›"Abdominal pain"
• ›"Regular painful contractions"
• ›"Amniotic fluid leakage"
• ›"Dyspnea before exertion" (dyspnea means shortness of breath)
• ›"Dizziness"
• ›"Headache"
• ›"Chest pain"
• ›"Muscle weakness affecting balance"
• ›"Calf pain or swelling"

The NHS rule is shorter: "stop if you feel uncomfortable, too hot or unwell."

Stop running and contact your doctor or midwife if any of these happen. Pain, pressure or leaking during runs is also worth raising with a pelvic health physiotherapist rather than running through.

What a sensible week can look like

This isn't a prescription. It's the guidance laid onto a calendar for an experienced runner whose care provider has agreed she can keep running.

The WHO and NHS 150-minute target is met with room to spare. Everything else is how you feel that week.

Before, during and after

Running while pregnant is one piece of a longer sequence. After the birth, a postpartum running plan follows a published return-to-running guideline that suggests waiting until at least 3 months postnatal. Much later, menopause and exercise raises different questions with the same evidence-first answer. The broader picture of exercise during pregnancy, including strength training and what to avoid, has its own post.

Outside pregnancy, knowing how to workout with menstruation matters for most of your running life. Hard conditioning in your 50s belongs in a guide to hiit workouts for women over 50, and lifting after birth has its own path, with postpartum strength training explained on its own terms.

How exrsz handles this

exrsz builds a periodized plan from your goal, schedule, level and equipment, balances running and lifting in one plan, adapts each week to how you actually trained, and reshuffles missed sessions instead of cramming them in. It doesn't give medical advice and doesn't replace your care provider. Check with your doctor, midwife or a pelvic health physiotherapist, then set your training around what they've agreed.

FAQ

Is it safe for a pregnant woman to keep running?

For regular exercisers with uncomplicated pregnancies, ACOG says high-intensity programs such as jogging should be possible with no adverse effects (ACOG, 2020). Check with your doctor or midwife first.

Can I start running while pregnant?

The NHS says it's not recommended to start a new vigorous activity like running in pregnancy (NHS). Walking, swimming and stationary cycling are gentler starting points.

How hard should I run while pregnant?

ACOG suggests using perceived exertion rather than heart rate, with moderate intensity at 13–14 ("somewhat hard") on the Borg scale, and the talk test as a check (ACOG, 2020). Harder sessions are a conversation with your care provider.

When should I stop running during pregnancy?

Stop and contact your doctor or midwife if you have any ACOG warning sign, such as vaginal bleeding, abdominal pain, regular painful contractions, amniotic fluid leakage, dizziness or chest pain (ACOG, 2020). Many runners also switch to brisk walking later in pregnancy, which the NHS mentions may feel more comfortable.