Exercise During Pregnancy Is Safer Than You Think

Sarah Potts had been an avid CrossFitter for years when she got pregnant last year. The 34-year-old firefighter from Niagara Falls, Ont., was told continuing CrossFit while pregnant was fine, but that she shouldn’t lift too heavy. Potts wasn’t sure what to make of that. What’s too heavy for someone else certainly wasn’t too heavy for her. After all, she could front squat close to 200 pounds. Potts heard there was new research about prenatal exercise available and reached out to Dr. Margie Davenport for more information.

Renee Lobb of Edmonton has a similar story. The 30-year-old teacher and skating coach found she was frequently asked by family members whether it was safe for her to keep lifting heavy while she was pregnant. She directed them to Davenport’s work.

When it comes to prenatal and postpartum exercise, Dr. Margie Davenport is leading groundbreaking research. As the director of the Program for Pregnancy and Postpartum Health at the University of Alberta, Davenport is rewriting outdated prenatal and postpartum exercise guidelines, researching the safety of sports many previously thought were unsafe and changing how pregnant women approach exercise during pregnancy. She’s published more than 200 manuscripts, including the world’s first-ever guideline to exercise postpartum, which was published in 2025.

Out with the old news

“I think it's pretty safe to say that more conservative, outdated guidance is still persisting in the prenatal field,” says Davenport.

It’s not uncommon for pregnant women to receive information from the Canadian prenatal exercise guidelines published in 2003, which were written based on limited research. Davenport explains that these guidelines had recommendations like keeping heart rate under 140 beats per minute and doing moderate aerobic exercise like walking and stationary cycling. If pregnant women lifted weights, the advice was to avoid lifting heavy.

Davenport explains that when these guidelines were made, there “were questions about if exercise was safe or not, and if it was safe for the baby or if it could potentially cause harm. Anything related to heavy weightlifting was taboo. Pregnant women were told not to lift above 20 pounds — and don’t even get me started on those traditionally riskier sports, such as rock climbing and contact sports like soccer,” Davenport says.

Davenport led the creation of Canada’s updated guideline for physical activity throughout pregnancy, which was published in 2019. It’s entirely evidence-based and recommends more activity and intensity: it encourages pregnant women to do at least 150 minutes of moderate-intensity exercise over at least three days a week and incorporate both aerobic and resistance training, provided they aren’t told to avoid exercise by their medical team.

“We were able to identify that, not only are there incredible benefits of being physically active in pregnancy, but there's a 40 percent reduction in the odds of developing major pregnancy complications like gestational diabetes, preeclampsia and gestational hypertension, and a 67 percent reduction in the odds of depression in pregnancy,” says Davenport. She adds there’s also evidence that exercise doesn’t increase miscarriage risk or low birth weight, either.

Yet awareness of these new guidelines is not happening fast enough. And high-intensity resistance exercise wasn’t included in the 2019 guidelines because of a lack of evidence at that time.

Davenport says, “I still get messages in my inbox almost every single day asking things like: ‘I ran and got my heart rate to 145 beats per minute. What harm have I done?’”

Yes, it’s safe to lift heavy

Since 2019, Davenport and her team have researched sports that were traditionally taboo in pregnancy. Some of her recent surveys and research have examined prenatal heavy lifting, endurance running and rock climbing. And it turns out, pregnant women don’t need to dial things back if they don’t want to.

In 2023, Davenport led survey-based research on pregnant women working occupational jobs.

“What we found was there was about a 51 percent reduction in the odds of having pregnancy complications if they continued to lift heavy during pregnancy, compared to those told to stop lifting,” says Davenport. Those results led to a study with in-person assessments, where Davenport and her team could measure maternal and fetal responses to high-intensity resistance training. The results were published in the British Journal of Sports Medicine in 2025.

The study followed 20 participants, half of whom were pregnant, as they performed three resistance exercises at increasing intensities: barbell back squat, bench press and deadlift. The results are game-changing.

“The study showed high-intensity resistance exercise is actually very well tolerated by the baby. The blood flow that is going to the baby is well maintained, and the exercise intensity is well tolerated by the mom as well,” says Davenport. She adds these participants lifted while lying on their back and breath-holding, known as the Valsalva maneuver, both of which were advised against in 2003.

Things are also looking good for pregnant women who want to keep up with other formerly considered risky sports while pregnant. Davenport’s evidence-based research on rock climbing while pregnant is set to be published this spring.

Davenport and her team continue to break barriers. Currently, she’s surveying pregnant women who skied while pregnant, doing research to offer exercise guidance for women experiencing infertility or assisted reproduction, and is interested in researching exercise in different environments during pregnancy, like cold water.

Healthy moms and healthy babies

Davenport’s research gives pregnant women like Sarah Potts and Renee Lobb the knowledge and reassurance they need to keep up their favourite sports throughout pregnancy. After connecting with Davenport, Potts felt confident she could safely continue her CrossFit workouts six times a week for her entire pregnancy, even doing gymnastics moves like handstand walks. And Lobb continued lifting heavy on average three times a week up to her last week of pregnancy. She even set a personal record while pregnant.

“With this research, women now are being championed for what they can do, as opposed to what they can’t do,” says Lobb. “Pregnancy is not an injury. It’s a superpower.”

When to be cautious about exercise

• It is safe for pregnant women with a typical pregnancy to begin lifting weights, even if they didn't before their pregnancy. However, like anyone starting a fitness routine, they should start slow and increase gradually.
• All women can participate in physical activity throughout pregnancy (which includes lifting) except for those who are advised by their medical team not to. That might include women with placenta previa, uncontrolled diabetes, early cervical dilation and uncontrolled hypertension.