With celebs bouncing back into their size 0 jeans less than a month after giving birth—and the internet’s recent obsession with moms-to-be maintaining six-pack abs—it’s no wonder pregnant women think a lot about what a bun in the oven means for their fitness. Whether you’re an avid gym-goer or a newbie to the exercise scene, Shyama Mathews, M.D., an OB-GYN in Princeton, New Jersey, says many women feel pressure to stay or get fit throughout their pregnancy.

Before you rush off to the gym, though, talk to your doc. “In your early appointments, bring up your desire to exercise, what you usually do, and what you want to do throughout your pregnancy,” says Mathews.

Then, assuming you have a healthy pregnancy and the doc gives the all-clear, it’s cool to start moving. Not only will exercise benefit you—moms experience increased blood flow to the uterus [which means more oxygen and nutrients to the baby], a decreased risk of diabetes, and generally have more energy when they exercise while pregnant—but it will also directly affect the baby’s growth and jump-start your postpartum recovery, says Mathews. Follow these guidelines through each trimester and before you know it you’ll be welcoming a healthy bundle of joy feeling just as healthy yourself.

FIRST TRIMESTER

Be prepared for energy drains. Many women figure out they’re pregnant after dealing with sore boobs, frequent nausea, and utter exhaustion—but Amanda Butler, certified personal trainer at The Fhitting Room in New York City (and soon-to-be mama herself), says getting into the gym can help with that third symptom. “In the first trimester, after I’d go to the gym I’d feel so much better,” she says. “It really helped boost my energy and my mood.”

Plus, strength training—with bouts of cardio and plenty of stretching—will better prepare your body for what’s going to happen throughout the next nine months. “You’re going to put on weight, so you want strong legs and a strong back to support the growing parts of your body,” says Butler. Not to mention a strong core will help you recover post-pregnancy, and will make tasks like picking up diaper bags and strollers easier later on.

Maintain a healthy diet. “One of the biggest wives’ tales is that you’re eating for two and anything goes,” says Mathews. Sure, you can have that bowl of ice cream if you’re really hankering for it, but you still want to eat healthy overall. After all, baby is getting the nutrients that you eat, so nourishing them with plenty of vitamins and minerals is a good call.

Sweat as usual. “In the initial stages of the first trimester, keeping up the level of activity that your body is conditioned to is perfectly fine,” says Mathews. So if you run, go ahead and keep running. If you lift, get after it. “Different things that might pop up later—back pain, bowel movement changes, joint pain—can be improved if you keep up with your fitness,” she says.

But there is one exception: “Contact sports and very aggressive forms of exercise, where direct trauma may come into play, should be avoided at any point of the pregnancy,” says Mathews. Butler also recommends modifying super high-impact exercises, like burpees, by jumping your feet in and out in a high-plank position.

But don’t start a brand-new workout routine. “Now is not the time to take on a new, aggressive routine,” says Mathews. This might sound like common sense, but both Butler and Mathews say many women try to start up a hardcore fitness routine as soon as they find out they’re pregnant, thinking they need to be in the best shape of their lives before delivery. But going from zero to marathon training just puts you at risk for dehydration, shortness of breath, and a higher risk of injury, says Mathews.

That said, this isn’t an invitation to become a couch potato. “Start slow, and listen to your body before jumping into more challenging exercises and routines,” says Butler.

SECOND TRIMESTER

Stay off your back.  “As the pregnancy progresses, the uterus gets larger and compresses vessels in the abdomen, so don’t lie on your back,” says Mathews. This can impede blood flow to the brain and make you feel lightheaded or dizzy, and in extreme cases may cause you to lose consciousness.” Instead, always make sure your heart is above your uterus when exercising.

And, any time you’re getting up from an exercise on the floor, push yourself up with your arms, much like you would when coming out of Savasana at the end of a yoga class, to avoid straining your core, says Butler.

Crunches are a no-go. Just like you don’t want to use your core to help you get up off the floor, you don’t want to be doing crunches either, says Butler. Both increase your risk of diastasis recti, a common occurrence in pregnant women that involves the abdominal muscles splitting. (Unfortunately this can’t always be prevented, but avoiding crunch-like motions may help safeguard against it.) If your doc confirms you’re free of this abs-splitting, stick with gentler core exercises like planks and side planks, which are typically a-okay in your first two trimesters, advises Butler.

Focus on strength training. Whether you have a lot of experience with strength training or not, building resistance work into your routine can make for a healthier pregnancy, says Butler—especially as you start to show and put on weight.

If you’re starting from scratch, Butler suggests finding a personal trainer who’s pre- and post-natal certified to show you what exercises are safe to do and which should be avoided. Or, if that’s not an option, don’t be afraid to ask your doctor for recommendations.

Either way, be careful about how you throw those weights around. When you’re pregnant, your joints—especially your hips—become more lax, which can increase your risk of injury, says Mathews. And as your uterus gets bigger in preparation for delivery, it places more pressure on the diaphragm, inhibiting your ability to take deep breaths. So move cautiously and lighten up the load, if needed.

Stretch, stretch, stretch. Stretching exercises, which you can find in prenatal yoga and Pilates classes, should be a regular part of your weekly workout routine, says Mathews, as they can help alleviate leg and back pain. You can still continue with vinyasa yoga classes—though you should avoid any style of hot yoga to avoid becoming overheated—so long as your instructor is aware of your pregnancy and comfortable helping you modify poses, says Butler.

Slow your roll. If you can keep up the same pace and intensity that you maintained before pregnancy—or even in the first trimester—hats off to you. It’s not impossible to do, but Mathews says it’s more likely that you’ll need to take things down a notch in your exercise routine. That’s because, in general, your body chemistry, metabolism, and rate of blood flow are all different when you’re pregnant—and these changes in blood flow may leave you lightheaded, dizzy, and short of breath, she says.

Throughout your second trimester, you may find you need to drop down the weight you lift, build in extra rest breaks, or cut out that final set of reps. Listen to your body and, as always, do what works for you.

THIRD TRIMESTER

Watch your balance. It’s likely that, by this point, your belly is getting quite big. And, other than an inability to see your toes, that affects your balance. “As your belly gets bigger, the way you distribute weight across your body and your center of gravity changes,” explains Mathews. “You may want to be more careful about things that may result in a fall.” So be wary of yoga poses or exercises that require extra balance.

Say hello to swimming. As your usual workouts become more difficult and you tire more easily, low-impact swimming can become a great form of exercise to incorporate into your fit pregnancy routine, especially in the third trimester, says Butler. Being in the water essentially gives you a break from the weight of your growing belly and can potentially alleviate any back pain, adds Mathews. Alternatively, you could also turn to the elliptical or arc trainer for cardio, which Butler says are easier on the joints.

Walk it out. Some women may have to give up running early on in their pregnancy, while others can tack on mileage right up through their due date. It’s all dependent on how your body responds to pregnancy, says Butler. “For me, running felt terrible because I felt like [my baby] was pressing on my bladder, so I felt like I had to pee all the time,” she says. “My heart rate would come up faster, too, so I had to stick to smaller distances and work in walk breaks.”

Speaking of, walking is something nearly every expectant mom can do, since it’s relatively low-impact and won’t spike your heart rate too much. Think of it as more of a leisurely stroll, and be cognizant of your breathing, hydration, and balance, says Mathews. Oh, and don’t be surprised if you experience a few small contractions here and there. “Those are not signs that you need to be on bed-rest, but it may mean you need more hydration and should lower the intensity,” she says.

As you approach your due date, just be aware that exercise may induce labor, says Mathews. (Docs often encourage women who are past their due date to take walks in hopes of kick-starting the process.)

Elevate your feet. If it hasn’t happened already, entering the third trimester likely means you’ll start to experience swelling (in the hands, ankles, and feet, especially) because you’re retaining fluid and the baby is getting bigger, says Butler. Make sure to elevate your feet after exercise to help alleviate some of that discomfort.

Beware of Braxton Hicks. These false contractions don’t send you into labor or progress labor, nor do they harm mom or baby—but they can be startling and uncomfortable, says Mathews. And they may be more likely to happen if you’re active. That’s because high levels of activity, coupled with dehydration, can bring them on. “If you do experience them, it may be a cue that you need to take it a little easier, and really make sure you’re staying hydrated,” says Mathews.

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