How Much Exercise Is *Actually* Safe to Do While Pregnant?

Post a selfie during a workout, and you'll usually get supportive "atta-girl!" type responses. But when Lea-Ann Ellison displayed a photo of herself doing a single-arm kettlebell squat, she was called "irresponsible" and stirred up an Internet firestorm—all because the 35-year-old mother was due in two weeks with her second child. But is Ellison's dedication to her intense workout routine really endangering her baby, or is she doing what's best for it by staying fit and healthy?

In short: Exercising while pregnant has minimal risks and has been shown to benefit most women, according to the American Academy of Obstetrics and Gynecology (ACOG). "Women who aren't deemed high risk can exercise while pregnant," says Carline Vilfort, M.D., D.O. And a heavy-lifting CrossFit routine like Ellison's likely won't cause any harm, either. "Doing CrossFit while pregnant is completely safe," says Katelyn Block, a certified CrossFit trainer in Rochester, NY, who works with women in all stages of life.

Unless your doctor advises that you avoid exercising while pregnant, the ACOG recommends getting your sweat on for 20 to 30 minutes daily. This can be in the form of a brisk walk around the block, a few laps in the pool, or a spin, Pilates, or low-impact aerobics class, according to the ACOG. Not only can exercising while pregnant help alleviate immediate health concerns like back pain, bloating, and swelling, but it can also lead to long-term benefits, including a decreased risk of gestational diabetes and long-term obesity, enhanced recovery from childbirth, and improved muscle tone, strength, and endurance, says Paul Sorace, M.S., fellow of the National Board of Fitness Examiners and a teacher at the American Fitness Professionals and Associates. (You'll love these fitness classes when you're expecting.)

While you don't have to treat your body like it's made of eggshells, there is one hitch: "If you were doing it prior to getting pregnant it's great to continue, but I wouldn't recommend starting a new routine that intense if you never did it before during pregnancy," says Jennifer Daif Parker, M.D., of Del Ray OB/GYN Associates. This especially goes for workouts like yoga, strength training, and running. If you've been a five-miles-before-breakfast-no-matter-what kind of gal long before you became expectant, you're likely able to continue your regimen, so long as you get the doctor's ok. But if you're the type who runs a 5k once a year, it's not best to start a rigorous routine now. As for strength training, the same litmus test applies: "If a woman was lifting weights before she got pregnant, chances are that she can keep lifting weight as long as she doesn't have to lie flat on her back or engage in heavy-lifting routines," says Dr. Vilfort.

For you Tough Mudders and adventure seekers, some workouts are taken off the table completely while you're pregnant, and for good reason. The ACOG recommends avoiding contact sports, activities with a high risk of falling, scuba diving, sky diving, and hot yoga or hot Pilates. "Overall, "women should go by their symptoms, what she is doing now compared to when she was not pregnant, and what her doctor allows," says Jim Pivarnik, professor of kinesiology and epidemiology at Michigan State University. (Here's how to modify a group fitness class for your pregnancy.)

What's more, exercising while pregnant looks different in each trimester. During the first trimester, in particular, you should avoid becoming overheated by drinking plenty of water, wearing loose-fitting clothing, and exercising in a temperature-controlled room (aka no hot yoga). Once you're in your second trimester, you should become a little more vigilant about what posture your body takes during your workout. After 12 weeks, the Office of Disease Prevention and Health Promotion advises avoiding any activities in which you lie flat on your back, which can cause your uterus to press on a large vein that returns blood to the heart and ultimately decrease your blood pressure. "Modify by using an incline bench, a stability ball or performing the movements standing with resistance bands," says Gina Harney, a NASM-certified personal trainer. "You also want to avoid prone positions (on your stomach), so modify by lying on your side or standing instead." If you're doing yoga, ask your instructor to help you find different ways to adjust poses as your pregnancy advances. In the final trimester, you should continue modifying exercises to stay off your back, and Harney recommends sticking to a routine featuring light strength training, flexibility exercises, and walks. Throughout the entire pregnancy, though, moves like cat-cow, good mornings, squats, and traditional dumbbell strength exercises can assist with stabilization, posture alignment, strengthening the pelvic floor, and core support, says Harney. (Don't forget to do these 5 exercises to prepare your body for childbirth, too.)

Even if you are taking a prenatal yoga class or completing another workout that's been given the thumbs-up by your doctor, you should still watch out for red flags, such as vaginal bleeding, muscle weakness, shortness of breath prior to exercise, calf pain or swelling, dizziness, headache, regular painful contractions, chest pain, and amniotic fluid leakage—all of which are signs you should stop exercising while pregnant.

Bottom line: Listen to your body, modify moves that make you uncomfortable as your pregnancy progresses, and cut exercises your doctor recommends avoiding (hi, sit-ups) out of our routine for now.