Quick answer: Yes — for most healthy, uncomplicated pregnancies, exercise is not only safe but recommended. ACOG (the American College of Obstetricians and Gynecologists) advises at least 150 minutes of moderate-intensity activity per week, and your cardiovascular, respiratory, and musculoskeletal systems are built to adapt and protect your baby throughout.
Key Takeaway: Your heart isn’t just working harder during pregnancy — it’s becoming more efficient. Moderate exercise, paced with the Talk Test, supports both your cardiovascular health and your baby’s development.
Pregnancy is one of the most remarkable examples of the human body’s ability to adapt.
In just nine months, your heart will pump nearly 50% more blood, your lungs will work harder to meet increasing oxygen demands, your joints will become more mobile, and your muscles will constantly adjust to support your growing baby.
It’s no wonder many women wonder: “Is it really safe to exercise while all of this is happening?”
For most healthy pregnancies, the answer is yes. Your body is remarkably well designed to support both you and your baby during moderate physical activity. Organizations like ACOG recommend regular exercise throughout uncomplicated pregnancies — at least 150 minutes of moderate-intensity aerobic activity per week — because of the many benefits it provides for both maternal and fetal health.
In this series, we’ll explore what happens inside your body during exercise — and why understanding these incredible adaptations can help you feel more confident moving throughout pregnancy, whether you’re working out at home or in a guided prenatal class here in Indianapolis.
Let’s start with the organ working hardest of all: your heart.
Your Heart Works Smarter, Not Just Harder
What’s Happening Inside Your Body
One of the earliest and most impressive changes during pregnancy is what happens to your cardiovascular system.
By the third trimester, your blood volume has increased by nearly 50% to supply oxygen and nutrients to your growing baby. Your heart pumps more blood with every beat, and your entire circulatory system becomes more efficient to meet the needs of both you and your baby.
When you exercise, your heart works a little harder to deliver oxygen-rich blood to your working muscles. You might wonder whether this means less blood reaches your baby — but your body has an incredible built-in protection system. During moderate exercise, blood flow to the placenta is maintained, allowing your baby to continue receiving the oxygen and nutrients needed for healthy development while your muscles receive the fuel they need to keep moving.
Exercise also improves overall circulation, helping prevent blood from pooling in your lower legs. Many women find this can reduce swelling, heaviness, and fatigue — especially later in pregnancy.
You may notice that your heart rate rises more quickly than it did before pregnancy. This is completely normal. Rather than aiming for a specific heart rate, experts now recommend exercising at a moderate intensity using the “Talk Test” — a pace where you can comfortably hold a conversation but would have difficulty singing.
Why It Matters
A healthy cardiovascular system benefits both you and your baby. Improved circulation helps:
- Deliver oxygen and nutrients to your growing baby
- Reduce swelling in the legs and feet
- Support healthy blood pressure
- Improve energy levels
- Increase endurance for the physical demands of pregnancy, labor, and motherhood
Perhaps most importantly, these adaptations demonstrate just how remarkably capable the pregnant body is. Your heart isn’t simply working harder — it’s becoming more efficient.
Did You Know? By the third trimester, your heart is pumping approximately 1.5 liters more blood every minute than it did before pregnancy. That’s one of the reasons everyday activities — and exercise — may feel more challenging, even if you were very active before becoming pregnant.
Putting Science Into Practice
Here’s how you can support your cardiovascular health throughout pregnancy:
- Aim for 150 minutes of moderate-intensity activity each week, unless your healthcare provider recommends otherwise.
- Use the Talk Test to monitor your intensity. You should be able to comfortably carry on a conversation while exercising.
- Stay well hydrated before, during, and after activity.
- Wear supportive footwear and comfortable clothing that allows you to move freely.
- As pregnancy progresses, focus less on intensity and more on quality movement, posture, breathing, and consistency.
- If you notice swelling in your legs or feet, try taking a short walk every hour instead of sitting for long periods.
Remember: every walk, swim, strength-training session, or prenatal fitness class is an opportunity to strengthen your cardiovascular system while supporting your body’s natural adaptations. If you’d rather have a certified coach guide your pace and form, that’s exactly what our
Pre & Postnatal Program at IN Fitness Club in Indianapolis is designed for.
Prefer expert guidance over guesswork? IN Fitness Club, located at 9525 N Meridian St, Indianapolis, IN 46260, offers prenatal-safe personal training and group fitness classes built around the Talk Test and trimester-specific modifications described in this article. Call (317) 669-2375 or stop by to schedule a consultation with one of our certified prenatal coaches.
Nurture Tip
As your pregnancy progresses, you may notice that lying flat on your back becomes uncomfortable. This isn’t simply because of your growing belly — the weight of your uterus can compress major blood vessels that return blood to your heart, temporarily reducing circulation.
Whenever possible, especially during rest or exercise recovery, try lying on your left side — often called the “left lateral position” in prenatal guidance. Research suggests this position improves blood flow back to your heart and supports circulation to the uterus and placenta. During labor, side-lying positions may also improve maternal cardiac output and optimize blood flow to your baby.
When Should You Call Your Healthcare Provider?
Most cardiovascular changes during pregnancy are completely normal.
Contact your healthcare provider if you experience symptoms that are sudden, severe, or don’t improve, including:
- Frequent or prolonged nosebleeds
- Heart palpitations that don’t resolve quickly
- Swelling that suddenly worsens or doesn’t improve overnight
- Persistent coughing or wheezing when lying down
- Fatigue that significantly limits your normal daily activities
Seek emergency medical care immediately if you experience:
- Chest pain
- Severe shortness of breath
- Fainting
- Sudden difficulty breathing
If you need emergency care, be sure to tell the healthcare team that you’re pregnant so they can provide the most appropriate evaluation and treatment.
The Big Takeaway
Your heart isn’t simply working harder during pregnancy — it’s becoming stronger and more efficient.
Every time you take a walk, lift weights, swim, or attend a prenatal fitness class, your cardiovascular system adapts to support both you and your growing baby.
Exercise during pregnancy isn’t about pushing your limits or maintaining your pre-pregnancy fitness level. It’s about working with your body — supporting the incredible physiological changes already taking place and preparing yourself for the endurance of labor, delivery, recovery, and the beautiful demands of motherhood.
Pregnancy is proof that the human body is capable of extraordinary things. Movement is one of the best ways to help it thrive — and our team at IN Fitness Club in Indianapolis is here to help you move safely, every trimester.
Frequently Asked Questions
Is it safe to exercise during pregnancy?
For most healthy pregnancies without complications, yes. ACOG recommends at least 150 minutes of moderate-intensity exercise per week, since regular activity supports maternal cardiovascular health and healthy fetal development. Always confirm with your own healthcare provider first.
What heart rate is safe when exercising while pregnant?
Rather than targeting a specific heart rate number, current guidelines recommend using the Talk Test: exercise at an intensity where you can comfortably hold a conversation but would struggle to sing.
How many minutes of exercise per week are recommended during pregnancy?
ACOG recommends at least 150 minutes of moderate-intensity aerobic activity per week for people with uncomplicated pregnancies, spread across most days of the week.
Why shouldn’t you lie flat on your back during pregnancy exercise?
Lying flat on your back lets the weight of the uterus compress major blood vessels that return blood to the heart, temporarily reducing circulation. Lying on your left side instead helps maintain healthy blood flow to your heart, uterus, and placenta.
Where can I find prenatal-safe exercise classes in Indianapolis?
IN Fitness Club, located at 9525 N Meridian St, Indianapolis, IN 46260, offers prenatal personal training and group fitness classes designed around ACOG guidelines and trimester-specific modifications. Call (317) 669-2375 to schedule a consultation with a certified prenatal coach.
Coming Next in the Inside the Pregnant Body Series
What Happens to Your Lungs When You Exercise During Pregnancy?
Discover why you’re more likely to feel out of breath, how your respiratory system adapts to support both you and your baby, and practical strategies to help you breathe — and move — more comfortably throughout pregnancy.
Ready to Move Safely Through Your Pregnancy?
Join a prenatal-safe fitness class or book a one-on-one session with our certified prenatal trainers at IN Fitness Club. IN Fitness Club — 9525 N Meridian St, Indianapolis, IN 46260 — (317) 669-2375
