Safe Exercise During Pregnancy: A Trimester-by-Trimester Guide

If you’re pregnant and wondering whether you should put your sneakers away for nine months — don’t. Unless your doctor has specifically told you otherwise, exercise during pregnancy isn’t just safe; it’s one of the best things you can do for yourself and your baby.

The American College of Obstetricians and Gynecologists (ACOG) is clear on this: pregnant people without medical complications should aim for at least 150 minutes of moderate-intensity aerobic activity per week. That’s about 30 minutes a day, five days a week. And if you were active before pregnancy, you can generally continue your routine with some modifications.

Let’s break down what that looks like in practice, trimester by trimester.

Why Exercise During Pregnancy Matters

The benefits of staying active during pregnancy are backed by substantial research:

For you:

Reduces risk of gestational diabetes by up to 50% in some studies
Lowers the risk of preeclampsia (pregnancy-related high blood pressure)
Helps manage healthy weight gain
Reduces back pain, constipation, and bloating
Improves mood and reduces symptoms of anxiety and depression
Improves sleep quality
Builds stamina for labor and delivery
Speeds postpartum recovery

For your baby:

Associated with healthier birth weight
May improve placental function and blood flow
Research suggests babies born to active mothers may have better stress tolerance and neurological development

The evidence is strong enough that both ACOG and the World Health Organization actively recommend exercise as part of routine prenatal care — not as an optional add-on, but as a core component of a healthy pregnancy.

General Guidelines for All Trimesters

Before we get into trimester-specific recommendations, here are the rules that apply throughout:

The “Talk Test”

The simplest way to gauge intensity: you should be able to carry on a conversation while exercising. If you’re so breathless that talking is difficult, dial it back. This is roughly equivalent to moderate intensity — you’re working, but not gasping.

Stay Hydrated

Drink water before, during, and after exercise. Dehydration during pregnancy can reduce blood flow to the placenta and trigger contractions. Keep a water bottle with you and sip frequently.

Don’t Overheat

Your baby can’t regulate their own temperature, so avoiding overheating is important. Exercise in well-ventilated spaces or air-conditioned environments during hot weather. Avoid hot yoga, hot Pilates, and exercising outdoors in extreme heat. Your core temperature shouldn’t exceed 39°C (102.2°F).

Eat Before You Move

Low blood sugar plus exercise is a recipe for dizziness and nausea. Have a small snack 30 to 60 minutes before working out — a banana, a handful of nuts, or some toast with peanut butter.

Listen to Your Body

Pregnancy is not the time to chase personal records or push through pain. Some days you’ll feel great and strong; other days, a gentle walk is all you’ve got. Both are fine. Your body is already doing extraordinary work — honor that.

Warm Up and Cool Down

Always start with 5 to 10 minutes of gentle movement (walking, light stretching) and end the same way. Your joints are looser during pregnancy due to the hormone relaxin, making you more susceptible to injury if you jump straight into intense activity.

First Trimester (Weeks 1–13)

What’s Going On

Your body is adapting to pregnancy, which means fatigue, nausea, and hormonal upheaval. The good news: if you were active before pregnancy, you can generally continue your existing exercise routine. The baby is well-protected at this stage, and there’s no evidence that normal exercise increases miscarriage risk.

Best Activities

Walking — easy to do anywhere, gentle on joints, no equipment needed
Swimming and water aerobics — the buoyancy takes pressure off your joints and back, and the water helps prevent overheating
Cycling — stationary bikes are ideal (balance changes as pregnancy progresses make outdoor cycling riskier later)
Low-impact aerobics — group classes or at-home videos designed for general fitness
Strength training — using light to moderate weights with proper form
Yoga — prenatal yoga classes are specifically designed for pregnancy; general yoga classes are also fine with some modifications
Pilates — excellent for core stability and posture

Modifications

If nausea is an issue, try exercising at the time of day when you feel least sick
Reduce intensity if fatigue is overwhelming — a 15-minute walk still counts
Stay hydrated even if drinking water is difficult (small, frequent sips)
Skip any activity that requires lying flat on your back for extended periods (more important in later trimesters, but good to be aware of)

What to Avoid

Contact sports (basketball, soccer, ice hockey) — risk of abdominal trauma
Activities with high fall risk (skiing, horseback riding, gymnastics, rock climbing)
Scuba diving — the pressure changes can cause dangerous gas bubbles in your baby’s blood
Hot yoga or hot Pilates — risk of overheating
High-altitude exercise above 2,500 meters (8,200 feet) unless you’re already acclimatized

Second Trimester (Weeks 14–27)

What’s Going On

Welcome to what many people call the “golden trimester.” Energy levels often bounce back, nausea fades, and you’re not yet big enough to feel very unwieldy. This is often the most comfortable time to exercise during pregnancy.

However, your body is changing. Your center of gravity is shifting forward as your belly grows, the hormone relaxin is loosening your joints and ligaments, and your blood volume is expanding rapidly.

Best Activities

Everything from the first trimester, plus:

Prenatal yoga — increasingly beneficial for flexibility, balance, and relaxation. Avoid poses that compress the abdomen or require deep twisting
Swimming — many people find this becomes their favorite pregnancy exercise as the belly grows. The water supports your weight beautifully
Prenatal fitness classes — specifically designed for pregnancy, these classes adjust movements and intensity appropriately
Moderate strength training — focus on functional movements that will help you in daily life and during labor (squats, lunges, modified planks)

Important Modifications

Avoid lying flat on your back after about week 20. When you lie on your back, the weight of your growing uterus can compress the inferior vena cava — the large vein that returns blood to your heart — potentially reducing blood flow to you and your baby. This is called supine hypotensive syndrome. Signs include dizziness, nausea, and shortness of breath.

Modifications:

For floor exercises, use a wedge or prop yourself at an incline (at least 30 degrees)
Side-lying positions work well for many exercises
Standing and seated exercises are good alternatives

Adjust your core work. Traditional crunches and sit-ups put pressure on the abdominal muscles that are stretching to accommodate your baby. Focus instead on:

Modified planks (from knees or against a wall)
Pelvic tilts
Bird-dog exercises (on hands and knees, extending opposite arm and leg)
Gentle side bends

Widen your stance. As your belly grows, a wider stance provides better stability during standing exercises like squats.

Pelvic Floor Exercises (Kegels)

This is a great time to start (or continue) pelvic floor exercises. Your pelvic floor supports the weight of your baby, uterus, bladder, and bowels, and strengthening it can:

Help prevent urinary incontinence during and after pregnancy
Support the weight of your growing baby
Aid in pushing during labor
Speed postpartum recovery

How to do Kegels: Contract the muscles you’d use to stop the flow of urine. Hold for 5 to 10 seconds, then release. Aim for 10 to 15 repetitions, three times a day. You can do them anywhere — at your desk, in the car, watching TV.

Third Trimester (Weeks 28–40)

What’s Going On

Your baby is growing rapidly, and so is your belly. Breathing may feel more labored as your uterus pushes against your diaphragm. Your joints and ligaments are at their loosest. You may experience swollen feet, back pain, and general heaviness. Exercise can help with all of these things, but the intensity and type will likely shift.

Best Activities

Walking — still the gold standard. Even a daily 20-minute walk provides significant benefits
Swimming and water exercise — often the most comfortable form of exercise in late pregnancy. The buoyancy provides relief from the weight you’re carrying
Prenatal yoga — focus on gentle stretching, breathing techniques, and relaxation. These skills translate directly to labor preparation (see our preparing for labor guide)
Stationary cycling — low impact and no balance concerns
Pelvic floor exercises — continue daily
Gentle stretching — for back, hips, and legs. Hip-opening stretches can be particularly beneficial as you approach labor

Important Modifications

Reduce impact — switch from jogging to walking, from high-impact aerobics to swimming
Shorten duration if needed — two 15-minute sessions may feel better than one 30-minute session
Avoid exercises that require balance — your center of gravity has shifted significantly
Don’t hold your breath — this creates excess intra-abdominal pressure. Breathe steadily and exhale during the effort phase
Stop if you feel contractions — Braxton Hicks contractions are normal, but if exercise consistently triggers them, ease up and hydrate
Avoid exercises that involve quick direction changes — your loosened ligaments increase injury risk

Preparing Your Body for Labor

Certain exercises in the third trimester can specifically help prepare your body for delivery:

Squats — strengthen the legs and glutes, and can help open the pelvis. Use a wall or chair for support
Pelvic tilts — help with back pain and optimal baby positioning
Tailor sitting (cross-legged on the floor) — stretches the inner thighs and opens the pelvis
Perineal massage — starting around week 34–36, gentle massage of the perineal tissue can reduce the risk of tearing during vaginal delivery. The Royal College of Midwives recommends this as an evidence-based practice

When to Stop Exercising and Call Your Doctor

Stop exercising immediately and contact your healthcare provider if you experience:

Vaginal bleeding or fluid leaking from the vagina
Dizziness or feeling faint
Chest pain or heart palpitations
Shortness of breath before you start exercising (breathlessness during exercise is different)
Headache that is severe or doesn’t go away
Calf pain or swelling (could indicate a blood clot)
Regular, painful contractions
Decreased fetal movement (after week 28, when you can feel your baby’s patterns)
Muscle weakness that affects your balance

These are ACOG’s warning signs, and they should be taken seriously.

Conditions That May Require Modified or Restricted Exercise

While exercise is recommended for most pregnancies, certain conditions may require you to limit or avoid physical activity:

Placenta previa (placenta covering or near the cervix) after 26 weeks
Preeclampsia or pregnancy-induced hypertension
Cervical insufficiency or cerclage placement
Persistent vaginal bleeding in the second or third trimester
Preterm labor in the current pregnancy
Preterm premature rupture of membranes (PPROM)
Severe anemia
Certain heart or lung conditions

If you have any of these conditions — or any other medical concerns — your doctor will give you personalized guidance. “Bed rest” is prescribed far less often than it used to be, but there are still situations where activity needs to be modified.

Building a Realistic Exercise Routine

Here’s a sample weekly plan that works for many pregnant people. Adjust based on your trimester, energy level, and preferences:

Monday: 30-minute brisk walk + pelvic floor exercises Tuesday: Prenatal yoga class (45–60 minutes) Wednesday: 30-minute swim or water aerobics Thursday: Rest or gentle stretching Friday: 20-minute walk + light strength training (bodyweight squats, modified push-ups, resistance bands) Saturday: Prenatal fitness class or 30-minute walk Sunday: Rest

This totals about 150 to 180 minutes of moderate activity per week — right in line with ACOG’s recommendation. But remember: some weeks you’ll do more, some weeks less. Consistency over time matters more than any single workout.

Exercise After a Sedentary Lifestyle

If you weren’t active before pregnancy, that’s okay — you can still start now. ACOG encourages previously inactive people to begin an exercise program during pregnancy. Just start slowly:

Begin with 5 to 10 minutes of activity per day
Gradually increase by 5 minutes per week
Walking is the best starting point
Aim to work up to 150 minutes per week over several weeks

There’s no need to jump straight into a 30-minute workout. Your body is adjusting to pregnancy, and starting gently reduces injury risk and makes it more likely you’ll stick with it.

Frequently Asked Questions

Can exercise cause a miscarriage?

There is no evidence that moderate exercise causes miscarriage. Most miscarriages in the first trimester are due to chromosomal abnormalities and are not related to physical activity. ACOG and WHO both support exercise throughout pregnancy for people without complications.

Can I run during pregnancy?

If you were a runner before pregnancy, you can generally continue running during pregnancy with your doctor’s approval. You may need to slow your pace, shorten your distances, and switch to softer surfaces (trails or a treadmill) as your belly grows. Many runners transition to walking or walk-run intervals in the third trimester, and that’s perfectly fine.

How do I know if I’m exercising too hard?

Use the talk test: if you can speak in full sentences during exercise, you’re at the right intensity. Other signs you’re overdoing it include feeling lightheaded, experiencing chest tightness, or needing an unusually long time to recover after a session. Your heart rate will naturally be higher during pregnancy, so heart-rate-based targets aren’t as reliable as perceived exertion.

Can I do ab exercises while pregnant?

You can work your core, but you should modify traditional exercises. Avoid crunches, sit-ups, and any movement that causes the abdominal wall to dome or cone outward (a sign of diastasis recti). Focus instead on modified planks, pelvic tilts, bird-dog exercises, and deep-core activation (transverse abdominis work). A prenatal fitness instructor can show you safe alternatives.

Is it safe to lift weights during pregnancy?

Yes, strength training with proper form is safe and beneficial during pregnancy. Use lighter weights with more repetitions rather than going heavy. Avoid heavy lifting that requires the Valsalva maneuver (holding your breath and bearing down). Focus on functional movements like squats, lunges, and rows. If you’re unsure about your form, a few sessions with a prenatal-certified personal trainer can be a worthwhile investment.

Sources

American College of Obstetricians and Gynecologists (ACOG). “Physical Activity and Exercise During Pregnancy and the Postpartum Period.” Committee Opinion No. 804, 2020.
ACOG. “Exercise During Pregnancy.” FAQ119, updated 2023.
U.S. Department of Health and Human Services. “Physical Activity Guidelines for Americans.” 2nd ed., 2018.
World Health Organization (WHO). “WHO Guidelines on Physical Activity and Sedentary Behaviour.” 2020.
NHS. “Exercise in Pregnancy.” 2024.
Royal College of Obstetricians and Gynaecologists (RCOG). “Physical Activity and Pregnancy.” Patient Information, 2023.
Davenport MH, et al. “Exercise for the prevention and treatment of low back, pelvic girdle and lumbopelvic pain during pregnancy.” British Journal of Sports Medicine. 2019;53(2):90-98.
Mottola MF, et al. “2019 Canadian guideline for physical activity throughout pregnancy.” British Journal of Sports Medicine. 2018;52(21):1339-1346.