The Truth About Exercising While Pregnant: It’s OK To Work Hard

Sometimes it seems the only exercise options for pregnant women are easy swimming, gentle yoga, and walking carefully in a field of pillows. But if you’re not satisfied with those, you’re in luck: many activities are safer in pregnancy than bystanders and even your doctor may realise.

Photos by Bonbon, Montse PB, Ilmicrofono Oggiono, cris cebrian, yonolatengo

When “Take It Easy” Isn’t Easy Advice To Follow

Well-meaning doctors, coaches, and mum friends may tell you to switch your goals away from races and games and PRs toward “training for birth” or focusing on keeping yourself and the baby healthy. If that works for you, excellent. That kind of intrinsic motivation makes it easy to stick to a good habit.

But for many women who were athletic to begin with, “take it easy” isn’t easy advice to follow. A quick poll of some of my sportswomen friends included comments like these:

“I was told to take it easy, not skate at all, walking was good enough. I went crazy from it. Thinking that anything that I loved doing would somehow kill my unborn baby. I still swam a half mile several times a week, biked 10 miles a couple times a week until my belly hit my knees…. but the fear really caused a severe depression. I felt as if I was no longer relevant as long as the baby was healthy.” — Carley

“Just preparing for delivery would have been completely unmotivating for me – I needed the race [a walking half-marathon] to help motivate me.” — Laura

“Well, having random people scold me for skating, moving chairs, bending over, house work, essentially doing anything but sitting and eating was really tiring and irritating. It was almost easier to do nothing and save myself the aggravation. Add to that some serious perinatal depression, heat and bad knees and before I knew it I put on 70 lbs. I think if people minded their own damn business about what I felt I was able to do while pregnant I would have lasted longer.” — Kati

There’s a tip in here for people who aren’t pregnant, too: if a pregnant woman is doing something you wouldn’t normally imagine a pregnant woman doing…chill out.

Many times I had discussed something with my health care providers and gotten their blessing, only to have some well-meaning bystander lecture me while I’m doing it — in one case, while I was on the starting blocks at the pool. (She had heard that pregnant women shouldn’t “dive”.) So if you’re the bystander, remember: that crazy pregnant lady has probably thought this through.

And if the crazy pregnant lady is you…here’s some information to help you out.

What Your Doctor Probably Gets Wrong

If you want to keep up a badass exercise routine during pregnancy, it’s important to find a doctor or midwife who you feel comfortable talking with, and who gives evidence-based advice. I was planning on keeping a don’t ask/don’t tell policy about my marathon training, but it turned out my midwives were incredibly knowledgeable and supportive.

Not everyone is as well-informed, though. Doctors are still telling pregnant women (and pregnant women are advising each other) to keep their heart rate below 140 when they exercise. This is ludicrously outdated advice. It came from a group of doctors who wanted to encourage pregnant women to exercise, so did some back-of-the-envelope calculations to find a safe limit. They figured exercise that was too strenuous might divert blood and oxygen away from the foetus, so they recommended the American Congress of Obstetricians and Gynecologists write a 140 bpm limit into their guidelines. One of the doctors later told ESPN:

[Dr. Raul Artal of Saint Louis University] said that, in 1985, he and another doctor used intuition and calculation to determine the 140 beats rule. Six months later, when actual testing of women in a lab proved them wrong, Artal said he asked for the 140 beats notation to be stricken from the guidelines.

“For some reason, people caught onto that and they never let go,” he said. “Each time I get asked about it, I said forget about it. I think it should be ignored.”

A quarter-century later, a study published in the Journal of Women’s Health found that while 99% of doctors and midwives believed exercise was beneficial in pregnancy, 64% still gave out the 140-beats rule. Most had no idea the rule had ever been changed.

In truth, the relationship between heart rate and effort fluctuates during pregnancy: higher than normal at the beginning of pregnancy, lower than normal toward the end. So even if you normally train with a heart rate monitor, you’re best off ditching it and working by effort.

The book Exercising Through Your Pregnancy is an excellent review of the medical research on exercise and pregnancy. It’s written by a research professor and an exercise physiologist, but it’s still readable for the average Jane. In the studies described, even frequent, vigorous exercisers end up with healthy babies. Sometimes the babies have a little less fat (but are normal sized otherwise), and sometimes they are born slightly earlier (but not prematurely).

The research supports women doing the types and intensities of exercise that they were used to pre-pregnancy, and supports the idea that “listening to your body” (in terms of effort levels, temperature, and other warning signs) is actually a very good gauge for determining what’s safe.

The Actual Risks (And What To Do About Them)

There are a few risks to mixing pregnancy and hard exercise, but in most cases these risks are manageable. (As always, talk to your trusted doctor or midwife rather than blindly following advice from the internet. This information is true to the best of my knowledge, but it’s not personalised to you.) Here are the factors that, absent other complications, healthy exercisers should consider:

• Blood flow to the foetus may be reduced during very hard exercise. This was the original concern that led to the 140-beats rule, and experts are still cautious about whether there should be a maximum effort level. Recent studies show that blood flow in experienced athletes doesn’t dip until they’re somewhere above 90% of their max heart rate, and since the blood flow returned to normal immediately afterward, that may not even be a problem. Experts agree that moderate exercise is safe, but you may want to steer away from doing a lot of work at the higher effort levels.
• High body temperature can be bad for the foetus, but it’s hard to reach dangerous levels from exercise, even in the heat. (High fevers are the more common cause of problems related to temperature.) As discussed in Exercising Through Your Pregnancy, pregnant women tend to dissipate heat well, and voluntarily stop exercise before they overheat to dangerous levels. Make sure you’re hydrating well; this helps control body temperature.
• Blood sugar can fluctuate, and as you’re exercising you could end up with low blood sugar that makes you feel dizzy and faint. This means you may need to pay extra attention to your fuelling plan, perhaps stopping mid-workout to grab a snack even if you usually don’t. On the bright side, exercise helps with blood sugar management in the long run, which is especially important if you might be at risk for gestational diabetes.
• High impact or contact sports generally get a severe no-no, although the baby is extremely well protected in the abdomen (especially in early pregnancy, when the uterus is still inside of the pelvis) and the risk of abdominal injury is very low. Even when a sport isn’t full contact, there’s a risk in any sport where you might fall. Some women aren’t comfortable bicycling or ice skating because of the risk of falling. Some even steer clear of high heels. This one is more of a judgement call that I feel the pregnant woman needs to make for herself: if you play full-contact hockey or football or roller derby, are you comfortable with the risk of taking a hard hit to the belly?

This isn’t a full list of the risks your doctor (or mum or friends or random bystanders) might worry about, of course. Talk with that trusted provider of yours for the full story.

What To Expect When You’re Exercising For Two

First of all, if you’re trying to keep up an exercise program, know that you might not see much improvement. When I was training for a marathon, it was frustrating to train harder and harder, only to see my times get slower and slower. Plan on working out at the same effort level as before, knowing that your runs will be slower and your weights will eventually need to get lighter. Shrug it off and ditch the watch. It happens.

Why not throw in the towel entirely? Keeping up fitness, even if you’re slow and sluggish for the moment, helps you return next season: you’re only taking a few weeks or months off, instead of a year or more. The year after I ran my pregnant marathon, I ran a half-marathon after barely training at all; I was coasting off the hard work I had done the previous year. (Some experts think there might be a performance boost that comes a few months after giving birth. This may be entirely mythical, but it’s nice to pretend you have super powers.) Exercise also helps you manage blood sugar and weight gain, two things that pregnant women sometimes struggle with.

Since you may not be able to do your usual workouts, consider shifting your goals to ones that will provide the most satisfaction. Maybe you’ll want to run longer or more consistently rather than faster, explore every mile of trails in the park, or master a new skill. While you might not want to take up a whole new sport, this is a great time to revisit an old activity you haven’t done in a while (Swim team? Archery?), or focus on an aspect of your fitness you sometimes neglect. (Bicep curls? Quick footwork?)

Finding like-minded friends is an important tool for keeping your head. You probably already have friends who are athletes, so connect with them and ask if they know of communities, whether in real life or, say, facebook groups, where pregnant and mum athletes can compare notes. Try CrossfitAndPregnant.com or the Women’s forum on Runner’s World.

I’ve said this already, but one of the best things you can do for your exercise program is to find a supportive doctor or midwife who you can involve in your decision making, rather than putting up with someone you hate and ignore. There really are conditions that can make exercise in pregnancy dangerous, and you’d want to be able to trust your provider if that ends up applying to you.

If you doubt your doctor, ask questions. When you get advice you don’t like, ask:

• What specifically is risky about this activity?
• Is there a strong evidence base to understand this level of risk? Where can I read more about it?
• If I decide to do this anyway, what can I do to mitigate the risks?

Risk management is a tough topic for anyone, and pregnancy brings a whole new set of risks and priorities you may not have considered before. Commit yourself to being well informed, listening to good advice, and making decisions based on your priorities, not somebody else’s.