Exercise During Pregnancy: What's Safe, Trimester by Trimester

For most pregnant women, exercise is not only safe but recommended. Australian guidelines encourage 2.5 to 5 hours of moderate activity each week, plus muscle strengthening on at least two days and pelvic floor exercises every day (Department of Health, 2021). What that looks like for you depends heavily on where you started. A woman who was running half marathons before pregnancy and a woman who was mostly walking to the car will have very different, equally valid, starting points.

This guide explains what the research shows, what changes across each trimester, what you can lift, which myths you can let go of, and the signs that mean you should stop and call your care provider.

Is it safe to exercise while pregnant?

Yes, for the majority of uncomplicated pregnancies. The Australian guidelines, the World Health Organization and the American College of Obstetricians and Gynecologists (ACOG) all reach the same conclusion: pregnant women without a medical reason to avoid it should be regularly active throughout pregnancy (Department of Health, 2021; Bull et al., 2020; ACOG, 2020).

The fear many women carry, that movement might somehow cause a miscarriage, is not supported by the evidence. A 2019 meta-analysis of more than 7,000 women found no association between prenatal exercise and miscarriage, and no association with perinatal death (Davenport et al., 2019a). Most of the studies looked at moderate exercise, and the authors rated the evidence quality as low, so this is best read as "no link found" rather than a guarantee. It is still reassuring, and it matches every major guideline.

There are some situations where exercise needs to be limited or avoided altogether. These include certain heart and lung conditions, placenta praevia after 26 weeks, preterm labour, ruptured membranes, pre-eclampsia, persistent bleeding and severe anaemia (ACOG, 2020). If any of these apply to you, or you are unsure, talk to your obstetrician, midwife or GP before you start or continue a routine.

What does the research say about the benefits?

The evidence base for exercise in pregnancy has grown substantially over the past decade. The most rigorous summaries come from a series of systematic reviews that informed the 2019 Canadian guideline, one of the most thoroughly researched pregnancy activity guidelines available.

Outcome	What the research shows	Source
Gestational diabetes, gestational hypertension and pre-eclampsia	Meeting the guideline was associated with around a 40% lower risk of these conditions, reported as a combined figure	CSEP (2018); Mottola et al. (2018)
Depression during pregnancy	Exercise-only programs were associated with 67% lower odds of prenatal depression	Davenport et al. (2018)
Birth	Exercise-only trials were associated with 24% lower odds of an instrumental birth (forceps or vacuum)	Davenport et al. (2019b)
Bladder leakage	Pelvic floor training during pregnancy was associated with a 62% lower risk of urinary incontinence in late pregnancy and 29% lower risk three to six months after birth	Woodley et al. (2020)

Equally important is what exercise was not linked to. The same body of research found no association between prenatal exercise and caesarean birth, induction, length of labour, perineal tears or diastasis recti (Davenport et al., 2019b). That is helpful to know. Exercise is not a guarantee of a particular birth, and nobody should feel they "failed" at it if their birth unfolds differently.

How much exercise should you do when pregnant?

The Australian guidelines recommend (Department of Health, 2021; Brown et al., 2022):

• Aerobic activity: 2.5 to 5 hours of moderate activity, or 1.25 to 2.5 hours of vigorous activity, across the week. Aim to be active on most, preferably all, days.
• Muscle strengthening: at least two days each week.
• Pelvic floor exercises: every day.
• Less sitting: break up long stretches of sitting or standing still.

If you were already doing more than this before pregnancy, or you train as an athlete, the guidelines recommend getting individual advice from a qualified health professional rather than following a generic plan.

How hard is "moderate"? Use the talk test

Heart rate targets are no longer the main tool. Current guidelines favour the talk test and your own sense of effort (Evenson and Hesketh, 2021; RANZCOG, 2024).

• Moderate: you can hold a conversation, but you could not comfortably sing.
• Too hard: you cannot finish a sentence without stopping for breath.
• On a 6 to 20 effort scale: "somewhat hard," around 12 to 14, suits most women. Women who were very fit before pregnancy may work a little higher (RANZCOG, 2024).

What changes in each trimester?

Your body is not the same at week 8 as it is at week 36, and your movement shouldn't be either. Think of each trimester as asking something different of you.

First trimester (weeks 1 to 13): move when you can, rest when you can't

For many women, the first trimester is when exercise feels hardest, even though the bump is invisible. Nausea, exhaustion and a body building a placenta from scratch are very real. There are no special restrictions in early pregnancy beyond the general ones below, so the main task is to listen.

• A 10 to 20 minute walk counts. So does gentle stretching on a day when nothing else is possible.
• If you had an established routine, you can usually continue it, scaling back as energy demands.
• Stay cool and hydrated. Avoid hot yoga, saunas and exercising in high heat or humidity (ACOG, 2020).
• Start pelvic floor exercises now. They are invisible work that pays off later.

Second trimester (weeks 14 to 27): the building window

Energy often returns in the second trimester, and this is where foundations get laid. As Ema Taylor, Mother Natal's Head of Education and clinical naturopath, puts it in her pregnancy work, birth preparation starts much earlier than most people think. By week 17, ligaments are loosening, your centre of gravity is shifting and your posture is adapting.

• Strength work becomes especially valuable for supporting your back, hips and changing posture.
• Swap deep abdominal work such as crunches and sit-ups for breath-led core activation, side-lying work and prenatal Pilates.
• Be mindful of balance. Your centre of gravity shifts as your bump grows, so activities with a high falls risk (horse riding, downhill skiing, mountain biking, gymnastics) are best avoided (ACOG, 2020).
• Watch your range. Joints can become more lax during pregnancy (Calguneri, Bird and Wright, 1982), so it is wise to stretch gently rather than chase new end ranges.
• Start reducing time flat on your back. See the section on lying on your back below.

Third trimester (weeks 28 to birth): adapt, soften, prepare

In the final trimester, the goal shifts from building to maintaining, easing discomfort and preparing for birth.

• Lower impact often feels better. Swimming, walking, stationary cycling and prenatal yoga are popular for good reason.
• Australian guidelines advise against exercising flat on your back after 28 weeks. Tilt to around 45 degrees with pillows, or work on your side (Brown et al., 2020).
• Pelvic floor work shifts focus. Practising full relaxation and release matters as much as strength as birth approaches.
• Breathlessness and pelvic pain are common. Shorten sessions, slow the pace and change positions slowly.

Can you lie on your back to exercise during pregnancy?

This is one of the most confusing areas, because guidelines genuinely differ:

• Australia: avoid exercising flat on your back after 28 weeks (Department of Health, 2021).
• RANZCOG patient advice: avoid strengthening exercises lying flat on your back after the first trimester (RANZCOG, 2024).
• ACOG: avoid lying flat for prolonged periods, as from around 20 weeks the weight of the uterus can reduce blood returning to the heart (ACOG, 2020).
• Canada: if you feel lightheaded, nauseous or unwell lying on your back, change position (Mottola et al., 2018).

The Australian evidence report notes that the research here is limited, and the advice is largely based on clinical expertise (Brown et al., 2020). A practical middle ground: from the second trimester, use an incline bench, pillows or side-lying for floor work, and change position straight away if you feel dizzy or unwell.

What can you lift when pregnant?

Strength training is recommended in pregnancy, not something to fear. What matters is how heavy, how familiar and how it feels.

• If strength training is new to you: start with body weight, resistance bands and light dumbbells. Squats, glute bridges (inclined later in pregnancy), wall push-ups, rows, side-lying leg work and sit-to-stands are good foundations.
• If you lifted regularly before pregnancy: you can generally continue with your care provider's support, reducing load as your body changes.
• Heavy lifting: the Australian evidence report does not recommend heavy lifting or intense repetitive isometric exercise, because information about safety is limited (Brown et al., 2020).

Research in experienced lifters is still emerging. In one survey of 679 women who lifted at 80% or more of their maximum during pregnancy, most were recreational athletes, and 66% reported no complications (DeVivo et al., 2022). Because this was a self-selected online survey with no comparison group, it cannot show heavy lifting is safe. It does suggest that for experienced lifters, decisions are best made individually with a care provider rather than by blanket rule.

Whatever your level, a few principles hold:

1. Breathe through the effort. Exhale on the hardest part of the movement rather than holding your breath.
2. Watch for doming. If you notice a ridge or bulge along the middle of your tummy during a lift, reduce the load or change the exercise.
3. Listen to your pelvic floor. Leaking, heaviness or dragging sensations are signs to scale back and see a women's health physiotherapist.
4. Drop the ego, not the habit. Lighter weights and more reps still build strength.

Which pregnancy exercise myths can you let go of?

Myth: "Keep your heart rate under 140"

The 140 beats per minute cap comes from 1985 ACOG guidance and was dropped in 1994. It is unclear how the number was ever derived (Evenson and Hesketh, 2021). Current guidelines favour the talk test and perceived effort.

Myth: "Pregnancy isn't the time to start exercising"

It is not the time to start an intense new program. But if you were inactive before pregnancy, the Australian guidelines encourage you to start with small amounts and build gradually (Department of Health, 2021). A daily walk is a perfectly good beginning.

Myth: "Exercise can cause a miscarriage"

No association has been found between prenatal exercise and miscarriage (Davenport et al., 2019a). Most early losses are related to chromosomal factors that have nothing to do with movement.

Myth: "You shouldn't lift anything heavy"

Strength training is recommended in every major guideline. The cautions apply to very heavy loads, unfamiliar lifts and anything that causes pain or pelvic floor symptoms, not to lifting in general.

Myth: "Exercise will give you an easier birth"

Exercise is associated with lower odds of an instrumental birth, but not with fewer caesareans or shorter labours (Davenport et al., 2019b). Move because it supports you, not as a test you pass or fail.

What are gentle ways to start exercising in pregnancy?

If you are starting from a low base, or getting back into it after a rough first trimester, small and consistent is the right approach. Ema's guidance is simple: the movement that matters most is the movement you will actually do.

1. Walk daily. Start with 10 minutes and add five each week. Outdoors, if you can.
2. Habit-stack your pelvic floor. Do a set while you brush your teeth, wait at the traffic lights or boil the kettle. Practise both the squeeze and the full release.
3. Try a prenatal class. Prenatal yoga or Pilates classes are designed around the pregnant body, unlike general classes, which may include deep twists, prone positions or heated rooms.
4. Get in the water. Swimming and aqua classes take load off your joints, which many women love later in pregnancy.
5. Add two short strength sessions. 15 to 20 minutes of body weight and band work is enough to meet the guideline.

When should you stop exercising and call your care provider?

Stop exercising and contact your midwife, obstetrician or GP if you experience any of the following (ACOG, 2020):

• Vaginal bleeding
• Regular, painful contractions
• Fluid leaking from the vagina
• Feeling short of breath before you start exercising
• Dizziness or feeling faint
• Headache
• Chest pain
• Muscle weakness affecting your balance
• Calf pain or swelling

If you have any concerns about exercising during your pregnancy, speak with your healthcare provider.

Key takeaways

• Exercise is recommended for most pregnancies, with 2.5 to 5 hours of moderate activity a week as the Australian target.
• Your starting point matters. Continue what you know, and build gradually if you are new to it.
• Use the talk test, not a heart rate cap.
• Strength training is encouraged. Heavy or unfamiliar lifting needs an individual conversation.
• From the second trimester, reduce time flat on your back, and avoid it after 28 weeks.
• Do pelvic floor exercises every day, practising both squeeze and release.

For trimester-by-trimester guidance on movement, nourishment and preparing for birth, Mother Natal's educational Companions cover every stage of pregnancy, written by Ema.

All content and media on the Mother Natal website are created and published online for informational purposes only. It is not intended to substitute professional medical advice and should not be relied on as health or personal advice.

Frequently Asked Questions

Can I keep running while pregnant? If you were running regularly before pregnancy and your pregnancy is uncomplicated, you can usually continue, adjusting pace and distance as your body changes. Many women swap to walk-run intervals or lower-impact options in the third trimester. Leaking, pelvic heaviness or pain are signs to scale back and see a women's health physiotherapist.

Is it safe to do sit-ups or crunches during pregnancy? Most practitioners recommend swapping crunches and sit-ups for breath-led core work from the second trimester, as your abdominal wall is stretching to make room for your baby. Side-lying exercises, bird dogs and prenatal Pilates are good alternatives. If you notice a ridge along the middle of your tummy, change the exercise.

Can I do hot yoga when pregnant? No. ACOG advises avoiding hot yoga, hot Pilates and exercising in high heat or humidity during pregnancy. Choose a prenatal class in a normal-temperature room and stay well hydrated.

How soon should I start pelvic floor exercises in pregnancy? As early as possible. Australian guidelines recommend daily pelvic floor exercises before and during pregnancy. A Cochrane review found pelvic floor training during pregnancy was associated with a lower risk of bladder leakage in late pregnancy and in the months after birth.

Is it safe to exercise in the first trimester? Yes. There are no special first-trimester restrictions for women with uncomplicated pregnancies, and research has found no link between exercise and miscarriage. The challenge is usually fatigue and nausea, so gentle and flexible is the right approach.

Which exercises should I avoid while pregnant? Avoid contact sports, activities with a high risk of falls, scuba diving, skydiving and exercising in extreme heat. Australian guidelines also advise against exercising flat on your back after 28 weeks and exercising at altitudes above 2,000 metres unless you are acclimatised.

Can I start going to the gym if I didn't before pregnancy? Yes, with a gradual approach. Start with light weights, bands and body weight exercises, ideally with guidance from a trainer experienced in pregnancy. Pregnancy is not the time to begin heavy or high-intensity training.

Does exercise during pregnancy make labour easier? Research shows exercise is associated with lower odds of a forceps or vacuum birth, but not with fewer caesareans or shorter labours. It is best seen as support for your body and mind rather than a guarantee of a particular birth.

References

American College of Obstetricians and Gynecologists (ACOG) (2020) 'Physical activity and exercise during pregnancy and the postpartum period: ACOG Committee Opinion No. 804', Obstetrics & Gynecology, 135(4), pp. e178–e188. Available at: https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2020/04/physical-activity-and-exercise-during-pregnancy-and-the-postpartum-period

Brown, W.J. et al. (2020) Evidence-based physical activity guidelines for pregnant women. Report for the Australian Government Department of Health. Available at: https://www.health.gov.au/sites/default/files/2023-02/evidence-based-physical-activity-guidelines-for-pregnant-women.docx

Brown, W.J. et al. (2022) 'Australian guidelines for physical activity in pregnancy and postpartum', Journal of Science and Medicine in Sport, 25(6), pp. 511–519. Available at: https://doi.org/10.1016/j.jsams.2022.03.008

Bull, F.C. et al. (2020) 'World Health Organization 2020 guidelines on physical activity and sedentary behaviour', British Journal of Sports Medicine, 54(24), pp. 1451–1462. Available at: https://doi.org/10.1136/bjsports-2020-102955

Calguneri, M., Bird, H.A. and Wright, V. (1982) 'Changes in joint laxity occurring during pregnancy', Annals of the Rheumatic Diseases, 41(2), pp. 126–128. Available at: https://doi.org/10.1136/ard.41.2.126

Canadian Society for Exercise Physiology (CSEP) (2018) Physical activity throughout pregnancy enhances physical and mental health and reduces risk of pregnancy complications [press release], 18 October.

Davenport, M.H. et al. (2018) 'Impact of prenatal exercise on both prenatal and postnatal anxiety and depressive symptoms: a systematic review and meta-analysis', British Journal of Sports Medicine, 52(21), pp. 1376–1385. Available at: https://bjsm.bmj.com/content/52/21/1376

Davenport, M.H. et al. (2019a) 'Prenatal exercise is not associated with fetal mortality: a systematic review and meta-analysis', British Journal of Sports Medicine, 53(2), pp. 108–115. Available at: https://bjsm.bmj.com/content/53/2/108

Davenport, M.H. et al. (2019b) 'Impact of prenatal exercise on maternal harms, labour and delivery outcomes: a systematic review and meta-analysis', British Journal of Sports Medicine, 53(2), pp. 99–107. Available at: https://bjsm.bmj.com/content/53/2/99

Department of Health (2021) Physical activity and exercise during pregnancy guidelines [brochure]. Canberra: Australian Government. 

DeVivo, M. et al. (2022) 'Impact of heavy resistance training on pregnancy and postpartum health outcomes', International Urogynecology Journal. Available at: https://doi.org/10.1007/s00192-022-05393-1

Evenson, K.R. and Hesketh, K.R. (2021) 'Monitoring physical activity intensity during pregnancy', American Journal of Lifestyle Medicine. Available at: https://doi.org/10.1177/15598276211052277

Mottola, M.F. et al. (2018) '2019 Canadian guideline for physical activity throughout pregnancy', British Journal of Sports Medicine, 52(21), pp. 1339–1346. Available at: https://bjsm.bmj.com/content/52/21/1339

Royal Australian and New Zealand College of Obstetricians and Gynaecologists (RANZCOG) (2024) Exercise during pregnancy. Melbourne: RANZCOG.

Woodley, S.J. et al. (2020) 'Pelvic floor muscle training for preventing and treating urinary and faecal incontinence in antenatal and postnatal women', Cochrane Database of Systematic Reviews, CD007471. Available at: https://doi.org/10.1002/14651858.CD007471.pub4