How to exercise when you're pregnant

I taught fitness classes until I was 39 weeks pregnant. For my cycling classes, I had to keep moving the handlebars up and the seat back to make room for my growing belly, but it didn’t stop me from getting a sweat on.

As a certified fitness professional, I often have clients and students ask me about safe ways to exercise while pregnant. While all pregnant women need to talk to their doctors, and modifications do need to be made, I’ve always believed we are on the side of overly cautious and that the idea that a woman should take it easy during pregnancy is outdated. It turns out that research now supports my belief.

“The benefits of activity during pregnancy are numerous,” says Michelle Mottola, a University of Western Ontario kinesiology professor whose research has been used to develop fitness guidelines in place around the world. “Exercise contributes to heart and lung health, and prevents excessive gestational weight gain, Type 2 diabetes and hypertension.”

So how do you know what kind of exercise is right for you? A lot depends on what shape you were in before getting pregnant. For example, active women with uncomplicated, low-risk pregnancies can keep doing most of their fitness activities, like running or classes, with modifications, like using lighter weights. Women who weren’t active before getting pregnant should begin a gentle exercise program, like walking, and build up their fitness level slowly.

According to guidelines released in 2018 from the Society of Obstetricians and Gynecologists of Canada and the Canadian Society for Exercise Physiology, pregnant women who don't have any medical restrictions should get at least 150 minutes of moderate intensity exercise a week, spread over at least three days. And women are encouraged to be active every day, with aerobic and resistance exercise.

“The important thing is to listen to your body and don’t overheat, dehydrate or do anything that involves joint pain or the chance of falling. If something isn’t comfortable, don’t do it,” says Mottola. After 16 weeks you shouldn’t exercise flat on your back*, because the weight of the pregnant uterus can push down on the inferior vena cava, a vein that carries blood back to the heart, or on the abdominal aorta, which is the main blood supply to the uterus.

Mottola’s research on strength training suggests it is better for a pregnant woman to opt for lighter weights and more repetitions to avoid unnecessary strain on the body. As for flexibility training, such as yoga, Mottola cautions pregnant women not to overstretch, because the pregnant body produces a hormone called relaxin that loosens the connective tissue around the pelvic joints. “We don’t know the effect relaxin has on other connective tissues, such as the knee or hip joints, so err on the side of caution: Stretch until you feel it and then release.”

According to Mottola, exercising can also improve your stamina to get through labour, and women who are fit during pregnancy recover from birth more easily. She adds that there are also numerous psychosocial benefits: “Active women have more energy, and exercise may offset postpartum depression.”

My son came out of the womb healthy and strong, and has been active ever since. My body bounced back quickly, and I was teaching again at six weeks postpartum. Watching my boy ride his bike today, I wonder how much he remembers about our prenatal spin classes.

*Expert tip: Even though you shouldn’t lie flat after 16 weeks, you can still do ab work: Just lift your upper body up 45 degrees (support your back with rolled-up towels) when doing exercises like abdominal curls. You can also strengthen the transverse abdominis, which acts like a corset around your middle, by sitting on a stability ball and doing Kegels.

Read more: Pregnancy workout: 13 easy moves Exercise: Pregnancy workouts in the water