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4 Common Myths About Exercise During Pregnancy: Debunked with Research

By Kelly Yager · · 6 min read

A smiling pregnant woman lifting light red dumbbells by a bright gym window.

4 Common Myths About Exercise During Pregnancy: Debunked with Research

Pregnancy is an exciting time full of physical changes and advice from all directions. Unfortunately, that advice doesn’t always align with the most up-to-date research. Many expectant moms hear warnings that working out could be harmful or that certain activities are off-limits, even when evidence suggests otherwise.

Below we’ll walk through four common myths about exercise during pregnancy and explain what the research and clinical guidelines actually recommend.

Myth #1: I shouldn’t work out while pregnant.

For many years, pregnancy was seen as a time to slow down and reduce physical activity. However, leading health organizations now recommend staying active throughout a healthy pregnancy.

“All women without contraindication should be physically active throughout pregnancy.”

— 2019 Canadian Guideline for Physical Activity throughout Pregnancy

If you are healthy and your pregnancy is uncomplicated, you can safely continue or begin moderate physical activity. The CDC puts it plainly: being active during pregnancy doesn't raise your chances of miscarriage, low birth weight, or early delivery. The 2019 Canadian pregnancy guidelines reviewed the research and found no link to any of them.

Large research reviews show that staying active during pregnancy lowers your odds of gestational diabetes, high blood pressure, and preeclampsia by roughly 40%. It also helps keep weight gain in a healthy range, may ease low-back pain, and is great for sleep and mood.

Four conditions side by side: preeclampsia 41% lower odds, gestational high blood pressure 39% lower, gestational diabetes 38% lower, excessive weight gain 32% lower.

Current guidelines recommend at least 150 minutes of moderate exercise a week, ideally spread over at least three days (moving every day is even better). Check with your provider first to make sure it's right for your pregnancy.

Myth #2: Lifting weights is dangerous.

Another common misunderstanding is that strength training is unsafe during pregnancy. In reality, resistance training can be a valuable and safe part of a prenatal fitness routine when it’s modified appropriately and performed with proper form.

Light-to-moderate strength work (weights, bands or bodyweight) helps you hold on to the strength you've built, and early research suggests it may help with posture and back comfort as your body changes.

A 2025 review of 50 studies in the British Journal of Sports Medicine found that women who did resistance training during pregnancy had lower odds of gestational diabetes, high blood pressure, and perinatal depression. Smaller studies also point to less excessive weight gain and, for some women, less back pain. The research is still growing, so programs should be tailored to you and your provider's guidance.

Four conditions side by side: gestational high blood pressure 58% lower odds, perinatal mood disorders 52% lower, gestational diabetes 38% lower, a very large baby 33% lower.

As with all exercise during pregnancy, it’s important to work with a healthcare provider or fitness professional who understands prenatal modifications so that strength training is safe, personalized, and effective.

Myth #3: My heart rate can’t go over 140 beats per minute.

The 140 bpm rule comes from 1985 guidelines, and it was dropped back in 1994. If you've heard it, you've heard advice that's over 30 years out of date! However, modern research and expert guidance have moved away from strict heart rate limits.

The “heart rate must stay under 140” rule is considered outdated, and clinicians now encourage women to use tools like the talk test — meaning you should be able to carry on a conversation while exercising — to gauge appropriate intensity.

“When you're doing moderate activity, you should be able to talk but not sing.”

— NHS

During pregnancy your blood volume goes up by almost half and your heart pumps about 40% more blood. Your resting heart rate usually climbs too, often by 10–20 beats per minute, so a fixed number like 140 doesn't fit your changing body. Experts note that heart rate during physical activity can vary widely between individuals, and there is no one-size-fits-all number that applies to everyone.

Moderate-intensity aerobic activity — enough to raise your heart rate and breathing but still allow comfortable conversation — is generally considered safe and beneficial for most pregnant women.

Listen to your body and stay cool and hydrated. Stop and call your provider if you feel dizzy or faint, get chest pain or shortness of breath that doesn't settle, or notice bleeding, leaking fluid, regular contractions, calf pain or swelling, or your baby moving less.

Stop exercising and call your provider if you feel dizzy or faint, have chest pain or a racing heart, shortness of breath that doesn't settle, vaginal bleeding, fluid leaking, regular painful contractions, severe belly, back or pubic pain, calf pain or swelling, a headache, or your baby is moving less than usual.

Myth #4: Core work is off-limits.

Many pregnant people are told to avoid all core work during pregnancy, usually out of fear of harming the baby or causing diastasis recti (abdominal separation). Some abdominal separation is a completely normal part of pregnancy. Research hasn't shown that exercise causes it, and early studies hint that staying active may even help, so there's no need to skip core work altogether.

Bar chart: share of 300 first-time mothers with diastasis recti was 33% at 21 weeks pregnant, 60% at 6 weeks after birth, 45% at 6 months and 33% at 12 months.

But not all core work is created equal, and core strengthening can be safe and useful when done appropriately.

The key distinction is between traditional exercises like crunches or sit-ups, which may not be appropriate, and deep core engagement and functional core movements that support the muscles around the abdomen and pelvis without placing excessive strain. Later in pregnancy, many providers suggest limiting time flat on your back, especially if it makes you dizzy or queasy. That's one reason to swap crunches and sit-ups for supported, upright or side-lying core work.

Gentle core and pelvic floor work, paired with good breathing, is a smart way to train. Staying active in pregnancy is linked to less back and pelvic pain, and daily pelvic floor training is shown to lower the chance of bladder leaks during pregnancy and after birth.

“Pelvic floor muscle training (e.g., Kegel exercises) may be performed on a daily basis to reduce the risk of urinary incontinence.”

— 2019 Canadian Guideline for Physical Activity throughout Pregnancy

As with strength training, adapted and guided core exercises — especially those taught by prenatal exercise specialists — allow you to build strength safely throughout your pregnancy.

Summary

Exercise during pregnancy is not only safe for most women — it’s recommended. The evidence shows that:

  • Being active helps improve physical and emotional wellbeing for both mom and baby.

  • Strength training can be safe and beneficial when appropriately modified.

  • Heart rate limits are outdated; focus instead on moderate intensity and how you feel.

  • Core strengthening is valuable when done with proper form and guidance.

Always consult your healthcare provider before beginning or changing your exercise routine during pregnancy, especially if you have medical complications. With the right information and support, staying active can be one of the most empowering aspects of your pregnancy journey.

Sources

Guidelines

Research

Cover photo by Gustavo Fring on Pexels.

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