One of the most frequent discussions I have with pregnant patients revolves around their level of physical activity during pregnancy. Usually, the woman is used to an active lifestyle involving regular exercise and she is inquiring whether she can continue exercising during pregnancy. Frequently, however, most of the conversation is spent dispelling myths she may have heard from a friend, read in a magazine or, most commonly nowadays, read online. Women are often advised not to do certain activities in pregnancy, typically not based on any scientific evidence, and sometimes even in direct opposition to the current evidence.
Exercise has many benefits in general, including overall health, weight control, stamina, balance and a reduction in certain conditions such as type 2 diabetes, hypertension and heart disease. Exercise also has benefits to pregnant women in particular. There is good evidence that it lowers the risk of gestational diabetes, fetal macrosomia (excessively large babies), back pain, excessive gestational weight gain and depression. There is some suggestion in the evidence that it may actually lower the risk of preterm birth. From a practical perspective, staying in shape is also helpful for postpartum recovery and for having energy to care for a newborn.
Exercise has potential risks as well. However, despite what many people think, the risks are primarily maternal (specifically musculoskeletal injury), not fetal. In fact, there is little evidence suggesting exercise has any negative impact on the fetus. Exercise does not cause miscarriage, birth defects or preterm birth (as stated above, it may actually lower the risk of preterm birth), nor does it cause people to go into labor at term (for all of you taking long walks and climbing stairs trying to go into labor, my apologies). Recommendations regarding exercise modifications during pregnancy are usually focused on reducing the risk of injury to the mother, not her fetus. For example, I advise against skiing due to the risk of skiing into a tree, not to a concern over altitude. That said, some common sense is probably in order as well. Although there is no known risk to excessive exercising, it hasn’t really been properly studied, so I advise against iron man training, marathons, century bike rides and other extreme exercising.
There is a myth that pregnant women shouldn’t ever have a heart rate above 140 beats per minute. This number is not based on any evidence that it causes harm. It was essentially created as a marker for “strenuous” exercise. Also, just because an exercise is strenuous, that doesn’t mean it is harmful. For typical exercise sessions (20–60 minutes), there is no known optimal level of exertion in pregnancy, nor an optimal definition of exertion for pregnant women. I typically use the “talk” rule: Pregnant women should be able to talk while they exercise. If they can’t talk, they are exercising too hard. As for the minimum level of exertion, exercise should make a pregnant woman’s heart beat faster, make her breathe heavier and most importantly, make her sweat.
Some pregnant women are advised not to exercise, such as those with certain medical problems, placenta previa and high risk for preterm birth. These recommendations are mostly based on expert advice and not on any evidence that exercise is actually harmful in these women. So, it is always wise to check with your doctor about your own exercise during pregnancy. But, if you are basically healthy and have an uncomplicated pregnancy, you should have few restrictions regarding exercise. Current recommendations are that pregnant women without a contraindication should exercise at a moderate intensity for 20–30 minutes a day, most days of the week.
The following are some exercises I recommend for pregnant women:
Yoga is probably my “go to” exercise for pregnant women. It combines aerobic exercise, balance, strength and flexibility with a healthy dose of serenity. It is also my first recommendation for women with back pain of pregnancy. It helps strengthen core muscles, which can be very helpful to support the back. Although there are specific prenatal yoga classes, that is mostly a marketing distinction. Any good yoga teacher will be able to modify your yoga practice as your body changes during pregnancy. I advise against “hot” yoga, simply because the likelihood of dehydration and fainting is much higher in pregnant women. Although inversions aren’t harmful, be sure to do them with a spotter or near a wall as balance can be more difficult in pregnancy and there is a higher risk of falling. Other poses only need to be limited by your actual physical ability to do them with your growing pregnancy.
Swimming is a full-body workout with a very low risk of injury. It also strengthens the back and core muscles and can be continued throughout pregnancy. It is a myth that pregnant women shouldn’t swim at the end of pregnancy (due to a fear that she will break her water and not know about it). Pregnant women often enjoy swimming, particularly towards the end of pregnancy, due to the weightlessness experienced in the pool. In the summer, it is also a nice way to cool off. NEVER swim without someone watching you. Being a good swimmer does not eliminate the risk of drowning, as pregnant women (actually, anyone) can develop a muscle cramp, inadvertently choke on water or accidentally bump their head on the wall of a pool. So, be safe.
Cycling is a great aerobic exercise for pregnant women, also with a low risk of injury, but that risk depends on the likelihood of falling off your bike or crashing into something. So, I definitely recommend spin cycling to pregnant women. As for biking outside, I advise against off road biking, and biking on highways or busy city streets. No matter how careful you are, you just cannot control if a pedestrian or car is going to cut you off or bump into you. As for biking on safe and designated bike paths, it is probably fine, but there is probably a small risk of injury.
Running is another great aerobic exercise for pregnant women who are already runners. Women who don’t run probably shouldn’t start during pregnancy. There is a risk of injuring your hip, knee or ankle and pulling a muscle as well. That risk exists for seasoned runners too, of course, but is probably lower. For women who don’t run, a brisk walk or speed walking is probably just as good from an aerobic perspective, and has a much lower risk of injury. Just be sure the walk is really brisk enough to cause you to sweat. For women who are good runners, I do support them continuing to run, but I warn them that they will likely need to run more slowly and shorter distances than they are used to, especially as pregnancy progresses. There is also a risk of falling, so be careful to run on well-paved roads or dedicated running paths.
Dance, step aerobics, elliptical machines and other exercises designed to get you moving are all appropriate for pregnant women as well, with the same limitations listed above for running. Higher-impact exercises should probably not be tried for the first time in pregnancy.
Exercises with light weights should be safe in pregnancy. Heavier weights are avoided due to the risk of a back or muscle injury.
Although many women believe they cannot exercise their abdominal muscles (sit-ups, crunches, pilates etc.) during pregnancy, there is no known risk and it can actually help avoid or alleviate back pain during pregnancy. So, I recommend core strengthening exercises in pregnancy, unless a woman is physically unable to do them due to the size of the pregnancy.
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Maternal Fetal Medicine blogs are intended for educational purposes only and do not replace certified professional care. Medical conditions vary and change frequently. Please ask your doctor any questions you may have regarding your condition to receive a proper diagnosis or risk analysis. Thank you!