Exercise in pregnancy: what is safe and what to avoid
Staying active during pregnancy is one of the best things you can do for your wellbeing and your baby's. The NHS recommends that most pregnant people aim for around 150 minutes of moderate-intensity activity each week, spread across the week in sessions of any length that suit you. Exercise in pregnancy can help reduce the risk of gestational diabetes, ease common discomforts like back pain, and support your mental health at a time when stress and anxiety are common. This article draws on NHS guidance to help you understand which activities are safe, which to avoid, and what warning signs should make you stop and seek advice.
Why exercise matters in pregnancy
Physical activity during pregnancy benefits both you and your baby. According to NHS guidance, regular moderate exercise can reduce the likelihood of developing gestational diabetes, ease lower back pain, help manage pregnancy-related stress, and improve sleep. Exercise also supports your cardiovascular fitness and strength, which can help you cope with the physical demands of labour. For people who were already active before becoming pregnant, maintaining that activity level, with some sensible adjustments, is generally both safe and encouraged. For those who were not exercising regularly before, pregnancy is a fine time to start, provided you begin gently and build up gradually.
Activities that are safe in pregnancy
Not all forms of exercise carry the same level of risk during pregnancy, and the NHS identifies a number of activities that are well suited to most pregnant people. The key is choosing movement that raises your heart rate and makes you breathe a little faster without pushing you to the point where you cannot hold a conversation.
- Brisk walking is one of the easiest and most accessible options throughout all three trimesters. It places minimal stress on the joints and can be adjusted easily as your body changes.
- Swimming and aquanatal classes are particularly comfortable later in pregnancy because the water supports your weight, reducing strain on your back and pelvis.
- Stationary cycling is a lower-risk alternative to road cycling, removing the possibility of a fall while still providing a good cardiovascular workout.
- Pregnancy yoga and pilates help build core strength, improve posture, and encourage relaxation. Look for classes specifically designed for pregnancy, as some poses in general classes may not be appropriate.
- Low-impact aerobics classes designed for pregnancy are another good option, combining cardiovascular activity with group support.
If you were running, weightlifting, or doing other more intense activities before pregnancy, you can often continue those activities with modifications, particularly in the first and second trimesters. Talk to your midwife if you are unsure what adjustments to make as your pregnancy progresses.
Pelvic floor exercises
Pelvic floor exercises are worth starting from the very beginning of pregnancy, not saving for after the birth. The pelvic floor muscles support the bladder, bowel and uterus, and they come under significant pressure as your baby grows. Strengthening them during pregnancy reduces the risk of urinary incontinence after birth and supports a quicker postnatal recovery. These exercises can be done anywhere at any time and require no equipment. Your midwife can guide you on how to do them correctly, as good technique matters more than quantity.
Activities to avoid in pregnancy
While exercise is beneficial, some activities carry risks that outweigh the benefits during pregnancy. The NHS advises pregnant people to avoid certain types of exercise, particularly as pregnancy progresses beyond the first trimester.
- Contact sports such as kickboxing, judo or martial arts that involve physical impact should be avoided because of the risk of a blow to the abdomen.
- Sports with a significant risk of falling, including horse riding, skiing, gymnastics and road cycling, are best set aside after the first trimester. A fall that might be minor in normal circumstances could have more serious consequences when you are pregnant.
- Exercising flat on your back after 16 weeks can cause the weight of the uterus to press on a major blood vessel called the vena cava. This can reduce blood flow to both the heart and the placenta. Short, incidental periods on your back are unlikely to cause harm, but sustained exercise in this position is worth avoiding from mid-pregnancy onwards.
- Scuba diving should be avoided throughout pregnancy. The changes in pressure involved in diving carry a risk of decompression sickness that could affect the baby, who has no way to protect against it.
- Exercising at high altitude if you are not already acclimatised is also something to discuss with your midwife.
As a general rule, if an activity carries a meaningful risk of a sudden fall or a physical impact to the abdomen, it is safer to switch to something lower risk for the duration of your pregnancy.
Staying safe during exercise
Whatever activity you choose, a few straightforward precautions will help you stay comfortable and safe. Keep yourself well hydrated before, during and after exercise, and take care not to overheat, particularly in hot weather or in very warm indoor environments. Warm up properly before starting and give yourself time to cool down afterwards. Wear supportive clothing, including a well-fitted sports bra, and choose footwear with good support if you are on your feet. If you are new to exercise, the NHS advises starting slowly and building up your activity level gradually rather than doing too much too soon.
Signs to stop exercising and seek advice
Most people can exercise through pregnancy without any problems, but there are warning signs that mean you should stop immediately and contact your midwife or maternity unit. Do not push through any of the following:
- Vaginal bleeding
- Difficulty breathing before you have even started exercising
- Dizziness or faintness
- Chest pain
- Pain or swelling in the calf
- A noticeable decrease in your baby's movements
If you experience any of these, stop what you are doing and get in touch with your midwife or maternity unit promptly. Do not wait to see if the symptoms pass on their own.
Frequently asked questions
Is it safe to exercise throughout pregnancy?
For most people with uncomplicated pregnancies, exercise is safe and beneficial throughout all three trimesters. If you have any pregnancy complications, check with your midwife or GP before starting or continuing exercise.
Can I keep running in pregnancy?
If you were running regularly before pregnancy, you can usually continue in the first and second trimesters, reducing intensity and distance as your body changes. Many people find running becomes uncomfortable in the third trimester and switch to walking or swimming. Listen to your body and reduce intensity if anything feels wrong.
Why should I avoid lying flat on my back after 16 weeks?
After about 16 weeks, lying flat on your back allows the weight of the growing uterus to compress the vena cava, a major blood vessel, which can reduce blood flow to the heart and to the placenta. Short periods on your back are not likely to cause harm, but sustained exercise or sleep in this position is worth avoiding from mid-pregnancy onwards.
What are pelvic floor exercises and why do they matter?
Pelvic floor exercises (sometimes called Kegel exercises) strengthen the muscles that support the bladder, bowel and uterus. Doing them regularly in pregnancy reduces the risk of urinary incontinence and supports recovery after birth. Your midwife can show you how to do them correctly.
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