Is running safe during pregnancy?

Running during pregnancy is safe for women who were already running regularly before they became pregnant, provided they make sensible adjustments as the pregnancy progresses. The NHS advises that if running was part of your routine before pregnancy, you can generally continue — your body is adapted to the demands of the sport.

If you were not running before pregnancy, starting to run from scratch during pregnancy is not recommended. Walking, swimming, or cycling are more appropriate starting points if you want to begin an exercise programme during pregnancy.

Running by trimester

First trimester

If you were running regularly before pregnancy, you can continue at your normal frequency and a similar effort level in the first trimester. Fatigue and nausea may naturally reduce your motivation and pace — listen to your body and take rest days when needed. There is no need to avoid running because of the pregnancy itself at this stage.

Avoid running in intense heat. Core temperature rises during vigorous exercise, and overheating in the first trimester — when major fetal development is occurring — is worth taking seriously. Run early in the morning or evening in warm weather, stay hydrated, and stop if you feel too hot.

Second trimester

Most women find the second trimester more comfortable for running than the first. Energy typically improves and the bump is still manageable. However, several changes are worth noting:

Pace will naturally slow. The increased weight of the uterus, growing blood volume, and cardiovascular demands of pregnancy mean your running pace will drop — often noticeably. This is completely normal and expected. Do not try to maintain pre-pregnancy paces; run to effort rather than speed.

Joint laxity increases. The hormone relaxin, which loosens the ligaments in the pelvis to prepare for birth, also affects other joints — the ankles, knees, and hips become slightly less stable. This increases the risk of ankle sprains on uneven terrain. Stick to well-maintained surfaces where possible and consider whether trail running carries more risk than it did before.

Pelvic floor awareness. The impact of running puts repeated load on the pelvic floor. If you notice any leaking of urine when running (stress urinary incontinence), this is a sign that your pelvic floor needs support. See a specialist women’s health physiotherapist — they can assess your pelvic floor and give specific exercises and advice. Do not push through leaking; it is a sign to reduce impact and seek assessment.

Third trimester

Many runners naturally transition to walking, swimming, or cycling in the third trimester as running becomes uncomfortable. The growing bump shifts the centre of gravity, alters running mechanics, and increases the load on the pelvic floor substantially. Some women run throughout their entire pregnancy without issues; others find it uncomfortable by 28–30 weeks. Both are normal.

If you do continue running in the third trimester, use a supportive maternity running belt or shorts with built-in bump support. Keep runs short and at a conversational pace. Avoid running alone in case you need assistance.

The pelvic floor and running

Pelvic floor health is the most important consideration for pregnant runners. Running is a high-impact activity and each footfall sends a force of two to three times body weight through the pelvic floor. As pregnancy progresses and the baby grows heavier, this load increases further.

Signs that your pelvic floor is struggling include:

  • Leaking urine when running, jumping, or coughing
  • A sensation of heaviness or dragging in the pelvis
  • Pelvic pain during or after running

If you experience any of these, book an appointment with a women’s health physiotherapist. This is available on the NHS in many areas, or privately. A physiotherapist can assess your pelvic floor function and give you a specific programme to support your running safely.

General guidelines for running in pregnancy

  • Use the talk test. You should be able to speak in short sentences while running. If you are too breathless to talk, slow down.
  • Stay hydrated. Drink water before, during, and after runs. Dehydration can trigger Braxton Hicks contractions.
  • Wear a supportive bra. Breast tissue becomes heavier and more sensitive during pregnancy. A well-fitted sports bra significantly reduces discomfort.
  • Choose good footwear. Running shoes should fit well and provide appropriate cushioning. Your feet may change size during pregnancy due to relaxin — have your shoes fitted properly.
  • Run on even surfaces. Uneven terrain increases fall risk as the bump grows and balance shifts.
  • Warm up properly. The extra mobility from relaxin can make cold joints more prone to strain.

When to stop running

Stop running and contact your midwife if you experience:

  • Chest pain or palpitations
  • Severe or unusual shortness of breath
  • Dizziness, light-headedness, or feeling faint
  • Abdominal pain, cramping, or contractions
  • Any vaginal bleeding or fluid leakage
  • Significant pelvic pain
  • Reduced fetal movement
  • Calf pain or swelling (seek urgent advice — this can indicate DVT)