The Short Answer
You can train in all three trimesters of a healthy pregnancy. ACOG recommends at least 150 minutes of moderate-intensity aerobic activity per week, from your first weeks right up to delivery. What changes from trimester to trimester is not whether you work out but how: your balance, joints, and blood flow shift, and your workouts should shift with them.
Key takeaways:
- The target is 150 minutes of moderate aerobic activity per week in an uncomplicated pregnancy, plus regular strength work.
- Weeks 1–13: keep most of your pre-pregnancy routine. Fatigue and nausea set the pace, not the pregnancy itself.
- Weeks 14–27: stop exercising flat on your back (the NHS draws the line at 16 weeks) and swap crunches for standing and side-lying core work.
- Weeks 28–40: go lower-impact, protect your balance, and train the positions you will actually use in labor.
- Vaginal bleeding, dizziness, chest pain, or regular painful contractions mean stop and call your ob-gyn.
This page is the trimester-by-trimester training plan. For the broader case for prenatal exercise, including benefits and common myths, start with our exercise during pregnancy guide.
The 150-Minute Rule Applies All Nine Months
ACOG recommends that pregnant women get at least 150 minutes of moderate-intensity aerobic activity every week: enough effort to sweat and raise your heart rate, while still being able to hold a conversation. The federal Physical Activity Guidelines for Americans give the same number and suggest spreading it through the week, for example 30 minutes on 5 days.
The payoff is well documented. According to ACOG's Committee Opinion 804, exercise in uncomplicated pregnancies is safe and is associated with lower rates of gestational diabetes, cesarean birth, and postpartum depression.
ACOG recommends at least 150 minutes of moderate-intensity aerobic activity per week throughout pregnancy, paired with strength training.
Two ground rules before the trimester breakdown:
- The talk test beats a heart-rate cap. The old advice to stay under 140 bpm was dropped decades ago. If you can talk but not sing, your intensity is about right.
- Already active? Keep going, with your ob-gyn's approval. New to exercise? Start small. According to ACOG, beginners can start with as little as 5 minutes a day and add 5 minutes each week until they reach 30 minutes a day.
First Trimester (Weeks 1–13): Protect the Habit
Your body has barely changed shape yet, and almost everything you did before pregnancy is still on the table. The real obstacles in these weeks are fatigue and nausea, so the goal is simple: keep the habit alive, even in small doses.
| Keep doing | Modify | Skip from now on |
|---|---|---|
| Running and brisk walking | Shorten sessions on heavy-nausea days | Scuba diving |
| Strength training with familiar loads | Train in cool rooms and drink more water than usual | Hot yoga and hot Pilates |
| Swimming and stationary cycling | Time workouts for your best hours of the day | Contact sports (soccer, basketball, boxing, hockey) |
| Yoga and Pilates (non-heated) | Trade max-effort sets for moderate, controlled work | Exertion above 6,000 feet if you live at low altitude |
A few first-trimester specifics:
- Overheating is the main physical caution. Skip heated studios and midday summer runs; your cooling system is now working for two.
- Work with the nausea, not against it. Many women feel best mid-morning or early evening. A 15-minute walk you actually take beats a 45-minute workout you keep canceling.
- Starting from zero? Begin with a daily 5 to 10 minute walk and build from there, per ACOG's beginner guidance.
For everything else happening in these weeks, from prenatal appointments to symptom timelines, see our first trimester complete guide.
Second Trimester (Weeks 14–27): Adjust for a Moving Center of Gravity
Energy usually comes back in the second trimester, which makes it the best training window of pregnancy for most women. Two changes matter now.
First, get off your back. According to the NHS, you should not lie flat on your back for long periods after 16 weeks, because the weight of your bump presses on the main vessel returning blood to your heart and can make you feel faint. Swap the flat bench for an incline, and floor work for side-lying, seated, or standing versions.
Second, respect looser joints. Pregnancy hormones soften your ligaments, which can make deep end-range stretching and repetitive jumping riskier for your hips and pelvis. If you develop pain at the front or back of your pelvis, especially on stairs or single-leg movements, read our guide to pelvic girdle pain in pregnancy and bring it up at your next prenatal visit.
| Keep doing | Modify | Skip from now on |
|---|---|---|
| Brisk walking, swimming, stationary cycling | Bench work: incline instead of flat | Anything lying flat on your back for long |
| Strength training (squats, rows, presses) | Core: bird dog, side plank, and Pallof press instead of crunches | Sit-ups and full front planks if you notice coning or doming |
| Running, if it still feels good | Reduce jumping and deep stretches as ligaments loosen | Sports with fall or collision risk |
| Prenatal yoga | Use wider stances as your bump grows | Hot classes of any kind |
If you love yoga, a structured class built for this stage handles all of these modifications for you; our prenatal yoga guide covers what to look for. And if running starts to cause pelvic heaviness or leaking, that is a pelvic floor signal, not a normal part of pregnancy: our pelvic floor exercises guide explains the fix.
Third Trimester (Weeks 28–40): Train for the Birth
The third trimester is about consistency, balance, and birth prep, not personal records. Your center of gravity has moved a long way forward, your joints are at their loosest, and your heart is already working harder at rest.
| Keep doing | Modify | Skip from now on |
|---|---|---|
| Walking and swimming (water carries the bump) | Strength: moderate loads, slower tempo, full control | Max lifts and breath-holding under load |
| Squats to a box or chair | Hold a rail, wall, or counter for balance work | Exercises requiring quick changes of direction |
| Wall push-ups and band rows | Break the 150 minutes into shorter, more frequent sessions | New sports or skills you have not practiced |
| Daily pelvic floor training | Rest as often as you need in class settings | Anything that leaves you unable to talk |
Three third-trimester priorities:
- Swim if you can. Water supports your weight, cools you, and takes pressure off your pelvis. Many women swim comfortably into week 40.
- Train the pelvic floor deliberately. Both strength and the ability to relax those muscles matter for delivery and recovery. Our Kegel exercises complete guide walks through the technique.
- Practice labor positions. Supported deep squats, hands-and-knees rocking, and hip circles on a birth ball double as workout and rehearsal.
A practical habit worth building now: log each workout, how you felt, and any symptoms in our pregnancy journal. A simple record makes it much easier to spot patterns and gives your ob-gyn something concrete to react to at appointments.
Off-Limits in Every Trimester
ACOG's avoid list applies from week 1 to birth:
- Contact sports and sports with a risk of abdominal hits: ice hockey, boxing, soccer, basketball
- Fall-risk activities: downhill skiing, water skiing, surfing, off-road cycling, gymnastics, horseback riding
- Skydiving
- Scuba diving (the baby has no protection against decompression sickness)
- Hot yoga and hot Pilates, which can cause overheating
- Exertion above 6,000 feet, unless you already live at high altitude
The NHS adds that even ordinary road cycling deserves caution as your bump grows and your balance changes; many women switch to a stationary bike in the second trimester.
Warning Signs: Stop and Call Your Ob-Gyn
Whether you are a seasoned athlete or a beginner, ACOG says to stop exercising and call your ob-gyn if you notice any of the following:
- Bleeding from the vagina
- Feeling dizzy or faint
- Shortness of breath before starting exercise
- Chest pain
- Headache
- Muscle weakness
- Calf pain or swelling
- Regular, painful contractions of the uterus
- Fluid gushing or leaking from the vagina
Occasional Braxton Hicks tightenings that fade when you rest are common in later pregnancy. Contractions that keep coming at regular intervals after you stop and drink water are different: time them with our contraction timer and call your provider.
Do You Need Medical Clearance First?
Most pregnant women can follow the plan above, but some conditions change the picture. Talk to your ob-gyn before exercising if you have any of these:
- Certain heart or lung diseases
- Cervical insufficiency or a cerclage
- Placenta previa after 26 weeks
- Preeclampsia or pregnancy-induced high blood pressure
- Severe anemia
- Risk factors for preterm labor, or a multiple pregnancy with such risk factors
Even with an uncomplicated pregnancy, bring up your exercise routine at an early prenatal visit so it is on the record and your provider can flag anything specific to you.
Decision Guide: What to Do Today
| If you are... | And you want... | The right choice is... |
|---|---|---|
| 6–13 weeks and exhausted | Something you can finish | A 10 to 15 minute walk plus gentle mobility |
| 14–27 weeks and feeling strong | A real cardio session | Brisk walking, swimming, or stationary cycling |
| 14–27 weeks with pelvic girdle pain | To keep moving without pain | Pool workouts; skip single-leg and wide-stance moves |
| 28+ weeks | To keep strength | Box squats, wall push-ups, band rows at controlled tempo |
| 28+ weeks | To prepare for labor | Pelvic floor work, supported squats, birth-ball mobility |
What Happens After Delivery?
The habit you protect now is the one you restart later. ACOG's Committee Opinion 804 covers the postpartum period too: activity can usually resume gradually after birth, with timing depending on your delivery and your provider's guidance. When you get there, our guide to strength training after birth picks up exactly where this plan leaves off.
Frequently Asked Questions
How much exercise is safe during pregnancy?
ACOG recommends at least 150 minutes of moderate-intensity aerobic activity per week in an uncomplicated pregnancy, spread across most days. Strength training is safe too, with trimester-appropriate modifications. Moderate intensity means you can talk during the activity but could not sing.
Can you start exercising during pregnancy if you didn't work out before?
Yes. ACOG advises beginners to start with as little as 5 minutes of activity a day and add 5 minutes each week until reaching 30 minutes a day. Brisk walking and swimming are the easiest starting points because they are low-impact and easy to scale.
When should you stop exercising on your back during pregnancy?
The NHS advises against lying flat on the back for long periods after 16 weeks, because the weight of the uterus can press on the vessel returning blood to the heart and make you feel faint. Use incline, side-lying, or standing positions instead.
What exercises should you avoid while pregnant?
ACOG says to skip contact sports, activities with fall risk (downhill skiing, horseback riding, gymnastics), scuba diving, hot yoga or hot Pilates, skydiving, and exertion above 6,000 feet unless you already live at altitude. These apply in every trimester.
What are the warning signs to stop exercising during pregnancy?
Stop and call your ob-gyn for vaginal bleeding, dizziness, chest pain, headache, shortness of breath before exertion, muscle weakness, calf pain or swelling, regular painful contractions, or fluid leaking from the vagina.
Is it safe to lift weights in the third trimester?
Yes, in a healthy pregnancy. Use moderate loads you can fully control, breathe through every rep instead of holding your breath, avoid lying flat on your back, and favor stable positions like seated or supported standing. Save max attempts for after recovery.
