Safe Exercise During Pregnancy: What You Can and Cannot Do

Staying active during pregnancy is one of the best things you can do for yourself and your baby. Safe exercise during pregnancy can significantly improve your physical health, mental wellbeing, and labour outcomes—and you don't need a specialist gym or fancy equipment to do it. The NHS recommends 150 minutes of moderate-intensity activity per week during pregnancy, the same as for non-pregnant adults. Most types of exercise are safe, as long as you know what to avoid and listen to your body.

The Case for Exercise in Pregnancy

Exercise during pregnancy isn't just safe—it's actively recommended. Regular activity reduces your risk of gestational diabetes, pregnancy-related high blood pressure, and excessive weight gain. It also improves your cardiovascular fitness, which helps during labour and recovery afterward.

Beyond the physical benefits, exercise is a proven mood-booster. Pregnancy hormones can make even the most positive person feel anxious or low at times. Regular movement helps regulate those hormones and gives you headspace away from the "am I doing this right?" questions that pregnant people tend to ask themselves at 3 a.m.

Your mental health matters just as much as your physical health during pregnancy—and exercise supports both.

Trimester-by-Trimester Guide

Your body changes dramatically over nine months, and your exercise routine should change with it. Here's what's realistic in each phase.

First Trimester (Weeks 1–12)

You might not look pregnant yet, but your body is working hard. Your heart rate is higher, you're breathing faster, and fatigue is real—some people describe first-trimester tiredness as "hitting a wall at 2 p.m."

If you already exercise regularly, you can usually keep doing it (check with your midwife if you have any risk factors). The key is listening to your body. If you've never exercised before, now isn't the time to train for a marathon—but a gentle daily walk is perfect.

Common challenges: nausea, extreme tiredness, sore breasts. If any of these hit hard, lower the intensity or take a rest day. Your baby isn't affected by a few missed workouts; your wellbeing is what matters.

Second Trimester (Weeks 13–28)

Many people say second trimester is the "honeymoon period" of pregnancy. Energy returns, nausea often eases, and your bump is visible but not yet cumbersome. This is often the best time to build your fitness.

You can do most exercises you did before pregnancy, with some modifications. Your centre of gravity is shifting, so balance-intensive moves (like standing on one leg) feel harder. Your ligaments are softening in preparation for labour, which means your joints are more mobile and more vulnerable. Don't bounce or use ballistic movements.

Your weight gain during pregnancy follows a predictable pattern by trimester—knowing what to expect helps you trust the process and adjust your exercise as needed.

Third Trimester (Weeks 29–40)

Your bump is big, your energy may dip again, and your feet might hurt. Walking feels slower. Your pelvic floor is under more pressure. Lying flat on your back for exercises is now off-limits (it can restrict blood flow to the baby).

This is the time to scale back intensity and focus on gentle movement and pelvic floor strength. Anything you do now is about maintaining fitness and preparing for labour, not building endurance. Most people move at a slower pace and do fewer repetitions—and that's exactly right.

Exercises That Are Safe During Pregnancy

Here are the go-to activities that work well across all trimesters (with modifications as needed):

Walking. The simplest and most accessible option. You can do it every day, anywhere, no equipment needed. Aim for a pace where you can hold a conversation but not sing. Flat, even ground is safest, especially in the third trimester.

Swimming and water aerobics. Water takes the weight off your joints and supports your bump, so many pregnant people find it the most comfortable exercise. The buoyancy reduces impact, and you can work as hard or gently as you like. It's safe right up to labour.

Prenatal yoga. Designed specifically for pregnancy, prenatal yoga builds strength and flexibility while teaching breathing and relaxation techniques useful in labour. Classes usually avoid full backbends and deep twists. Many pregnancy apps offer yoga routines, though an in-person class helps you get form right.

Stationary cycling. Lower impact than running, and your centre of gravity stays stable. Indoor bikes are better than outdoor ones during pregnancy (fewer fall risks).

Pilates. Great for core strength and pelvic floor awareness, both helpful in labour. Avoid moves that put pressure on your abdominal muscles or involve lying flat on your back after early pregnancy.

Strength training with weights. If you did this before pregnancy, you can continue. Use lighter weights and higher reps; avoid heavy lifts and straining. Stop if you feel dizzy or uncomfortable.

Pelvic floor exercises (Kegels). These aren't fun, but they're vital. A strong pelvic floor helps with continence during and after pregnancy and may reduce labour pain. Aim for 3 sets of 8–12 contractions per day.

What to Avoid

Some activities carry genuine risks during pregnancy and should be off your list:

Contact sports (rugby, football, hockey, martial arts) — collision risk is too high
High-impact activities (jumping, running long distances, plyometrics) — especially in the third trimester when your joints are destabilised
Sports with fall risk (skiing, horse riding, gymnastics, rock climbing) — even a low-speed fall can harm the baby
Scuba diving — the pressure changes and decompression risk are not safe
Hot yoga or Bikram yoga — overheating in early pregnancy may increase miscarriage risk
Anything requiring you to lie flat on your back for long periods (especially after 16 weeks) — it can reduce blood flow to the placenta
Heavy weightlifting or straining — avoid breath-holding under load; it raises intra-abdominal pressure

Track how you feel and any physical changes week by week—pregnancy brings surprises, and your exercise tolerance may shift.

Warning Signs to Stop Exercising

Stop exercising immediately and contact your midwife or GP if you experience:

Vaginal bleeding
Chest pain or severe shortness of breath
Dizziness, faintness, or blurred vision
Severe or persistent headache
Calf pain, swelling, or redness (sign of blood clot)
Sudden gush of fluid from the vagina (possible amniotic fluid leak)
Severe abdominal or pelvic pain
Contractions or signs of labour starting early

These aren't common, but they need immediate medical attention. Never push through pain or unusual symptoms assuming "it's just pregnancy."

How to Exercise Safely: Key Principles

Check with your midwife first. If you have gestational diabetes, high blood pressure, or any other pregnancy complication, your exercise plan may need tweaking.
Stay hydrated. Your blood volume increases in pregnancy, and overheating is a genuine risk. Drink water before, during, and after exercise.
Don't overheat. Ambient temperature + exercise heat + pregnancy = easy overheating. Wear layers you can shed, exercise in a cool environment, and back off if you feel hot.
Avoid the Valsalva maneuver. This is breath-holding under strain (like lifting heavy weights). Instead, breathe steadily throughout.
Pelvic floor awareness matters. During and after pregnancy, your pelvic floor does extraordinary work. Exercises that load it (running, jumping) should be balanced with pelvic floor training.
Progress gradually. If you're new to exercise, start with 10–15 minutes of gentle activity per day. Build up to 150 minutes per week over several weeks. If you already exercise, you can maintain or build, depending on how you feel.
Rest days are part of the plan. Your body is doing a lot. Two or three rest days per week is normal and healthy.

Frequently Asked Questions

Can I run while pregnant? Yes, if you ran before pregnancy. Many people run throughout pregnancy. Keep intensity moderate (you should be able to talk), stay well-hydrated, and avoid high temperatures. In the third trimester, the impact on your joints increases and many people slow to a walk. Listen to your body—some pregnancies feel great for running, others don't.

Is it safe to exercise in the first trimester when miscarriage risk is highest? Yes. Exercise does not increase miscarriage risk. Miscarriage is usually caused by chromosomal issues unrelated to physical activity. If you have a history of miscarriage, discuss exercise with your GP, but gentle movement is generally fine.

What's the difference between "moderate" and "vigorous" exercise? Moderate intensity is where you can talk but not sing (like a brisk walk). Vigorous is where you can only say a few words (like sprinting). The NHS recommends 150 minutes of moderate activity per week, not vigorous activity. If you trained at vigorous intensity before pregnancy, you may be able to continue in smaller amounts, but discuss this with your midwife.

Can exercise trigger labour? Gentle exercise does not trigger labour. Very strenuous exercise in the third trimester might increase Braxton-Hicks contractions (practice contractions), but these aren't labour. If you develop regular, painful contractions, stop exercise and contact your midwife.

What if I'm overweight at the start of pregnancy? Should I try to lose weight? No. Pregnancy is not the time to lose weight, regardless of your pre-pregnancy BMI. Healthy weight gain during pregnancy supports your baby's development. If you're concerned about your weight, discuss it with your midwife. Exercise is about fitness and wellbeing, not weight loss.

I've had a caesarean before—can I exercise in this pregnancy? Yes, with precautions. You can do most activities, but avoid heavy ab work and high-impact activities until your scar is fully healed (usually 12–18 months after surgery). Your recovery timeline after birth will guide your exercise decisions. Discuss your specific situation with your GP or midwife.

Is it too late to start exercising if I haven't been active before pregnancy? Never too late. Start gently—10–15 minutes of walking per day is perfect. Build gradually over a few weeks. You don't need to reach 150 minutes per week; something is better than nothing, and your body will thank you.

The Bottom Line

Safe exercise during pregnancy can transform how you feel physically and mentally. You don't need a special programme or expensive classes. A daily walk, a swim, or a prenatal yoga video is enough. The key is consistency, listening to your body, and checking with your midwife if anything feels wrong.

Your pre-pregnancy fitness level and BMI provide a starting point—but pregnancy is an opportunity to focus on how your body feels, not how it looks.