When your mom was pregnant with you, chances are, she wasn’t pedaling furiously at spin class or doing ball squats. Back then, doctors worried that exercise might harm the growing baby and discouraged pregnant women from breaking a sweat. Now, that’s completely passé. Researchers have realized that prenatal inactivity—not exercise—puts moms-to-be and their babies at risk. “For low-risk pregnancies, prenatal exercise is absolutely safe. There’s no question about that anymore,” says Michelle Mottola, Ph.D., director of the exercise and pregnancy lab at the University of Western Ontario. (Of course, if you’re having a high-risk pregnancy, consult your doctor about how much exercise is appropriate.) Using your nine months as a license to loaf, on the other hand, can make you more prone to excessive weight gain (which raises your odds of a C-section), pregnancy-induced high blood pressure and gestational diabetes (which can increase a baby’s obesity and diabetes risk years later). And taking an extended exercise hiatus has long-term consequences too.
Women who gain too much weight during pregnancy (beyond about the 25 to 35 pounds that doctors recommend) tend to hang on to those extra pounds long after their labor day, and those moms-to-be who develop gestational diabetes have a higher chance of developing type II diabetes within four years, according to Mottola. (Check out our BMI calculator to determine how much weight you should gain during pregnancy.)
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Fortunately, there’s plenty of incentive to exercise. Those awesome post-gym endorphins keep your mood and energy up, helping you combat sluggishness. Plus, regular sweat sessions build your strength for delivery and ease back pain.
Everyone should be active during pregnancy, experts say—including women who led sedentary lives before conceiving. Obese moms-to-be with gestational diabetes who work out in addition to controlling their calories gain less weight and deliver healthier babies than those who simply watch what they eat, according to research from St. Louis University.
Fit women who work out during pregnancy are healthier 20 years later than those who take a nine-month leave of absence from the gym. In one long-term study of 39 women, those who had exercised throughout their pregnancy gained only about 7 pounds in the two decades since, compared to nearly 22 for the women who’d spent their pregnancies on the couch. Basically, working out when you’re expecting lays the groundwork for staying fit even after your baby goes to college.
Related: The Truth About Prenatal Exercise
So exactly how much exercise do you really need to be doing to reap all these great benefits? If you were inactive before pregnancy, start off with 15 minutes of continuous exercise three times a week, gradually edging yourself up to 30-minute sessions four days a week, says Mottola. If you’re having a rough first trimester, and just reading this is making you nauseous, wait until the second tri to start. Already break a sweat regularly? You don’t need to drastically scale back your fitness routine, but do listen to your body, advises James F. Clapp III, M.D., coauthor of Exercising Through Your Pregnancy.
Related: 7 Prenatal Exercise Classes
It goes without saying (but we’ll say it anyway!) that pregnancy isn’t the time for activities that carry a high risk of wiping out—sorry, no snowboarding! If you’re a runner, jogging is OK if you feel up to it, but many moms-to-be switch to walking at some point because the pounding takes a toll on their hips, knees and feet. And you don’t want to push yourself too hard. Experts agree the “talk test” is a good gauge: “If you can carry on a conversation, you’re fine,” Mottola says. If you’re too winded to chat, take it down a notch.
Strength training gets the thumbs-up as well, as long as you don’t overexert yourself. Grab lighter weights but do more reps—15 to 20 instead of the usual 8 to 12, advises Mottola. A personal trainer who specializes in prenatal fitness can help you tweak your strength workouts for each trimester, so ask your gym if they have any specialists who can help. Pilates and prenatal yoga are also excellent ways to maintain your muscle tone and strength; look for prenatal classes that don’t have you lying on your back.
Ready to get moving? Find the best prenatal workouts for you.