Trail Running While Pregnant: What You Need to Know

Medical professionals and coaches say it's both safe and beneficial for most pregnant women to continue running on trails, with caveats.

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For those of us who love the trails, the thought of staying off them for nine months is all but inconceivable.

Fortunately, medical professionals and seasoned coaches say it’s both safe and beneficial for most women to continue running on trails, with caveats, throughout pregnancy.

Among the most common advice pregnant women hear from their doctors and midwives is to stay active. That’s for good reason. Exercise can decrease the risk of gestational diabetes, preeclampsia, back pain, constipation and other pregnancy-related conditions, according to the American Congress of Obstetricians and Gynecologists.

New guidelines from the International Olympic Committee go a step further than just promoting activity: They say elite and recreational athletes with low-risk pregnancies can even, for the most part, continue with their training regimens.

However, as I’m currently experiencing in my own first pregnancy, symptoms like fatigue, nausea and the aches and pains associated with a growing body will make many runners naturally want to back off a bit during this time. And that’s O.K., too.

“The most important thing is people aren’t sedentary during pregnancy—that they’re not afraid and listening to people telling them they shouldn’t be running,” says Tracy Hoeg, a physician at the University of California, Davis in physical medicine and rehabilitation and a member of the American trail ultra team in 2013. “They’re doing a favor to themselves and their babies by exercising.”

Trail running does, of course, carry some inherent risks, so women in this stage of life will want to talk to their doctors about their specific pregnancy profiles. But here’s some general wisdom gathered from the experts.


There’s no way around it—falls happen on trails. During pregnancy, and especially in the later trimesters, your center of gravity changes and your joints loosen, which some say can make it easier to lose your balance.

And while knee scrapes and shin bruises are one thing, falls that impact the abdomen can be more risky. They won’t necessarily lead to problems—the baby is enveloped by amniotic fluid and a muscular uterus designed to protect it from harm. But experts say there’s a risk falls can cause a disruption in the connection between the placenta and the uterus, which can be very serious. (Though it’s worth noting that most of what researchers know about placental abruption is from women in vehicle accidents, not those with sports injuries.)

“The biggest risk for falls would be if you’re in a race with technical terrain, and on downhills,” says Hoeg. Pregnant runners will want to be extra careful navigating rocks and roots, and likely refrain from bombing down the declines.

Robin Watkins, a certified nurse midwife in Washington, D.C., and winner of two 100-mile races in Virginia, recommends women get to know how their balance has changed before heading to the woods. “Practice running on roads or on more stable ground first, just to get a sense of how your body feels different so you can feel more confident when you’re running on trails,” she says.

Hydration and Heat

Not a ton has to change in how runners fuel themselves, though pregnant women should carry a bit extra.

“Both the pregnant and non-pregnant should drink when they’re thirsty,” says Hoeg. “But pregnant women should always have something with them.”

Mild dehydration during pregnancy can increase constipation (already a problem for most pregnant women) and cause false contractions, known as Braxton Hicks.

As for nutrition, most experts say pregnant women need to eat only about an additional 300 calories per day starting in their second trimester. But hunger patterns can certainly be unpredictable during pregnancy. I now bring snacks on even short five- or six-mile runs to keep my energy up. “Basically always bring more than you usually do, just in case,” says Liza Howard, a coach for Sharman Ultra Endurance and the winner of the 2015 Leadville Trail 100.

RELATED: Busting 6 Myths About Running While Pregnant

Mileage vs. Intensity

There’s no science to determining how much mileage a pregnant runner can put in. Instead, runners will want to make that decision based on their current fitness levels and how they feel at any time.

During the initial months of her first pregnancy, Hoeg had some extra free time and began putting in 16 trail miles a day. “I was like, it feels good and the woods are so beautiful,” she says. “I didn’t have morning sickness.” She bumped down to 13 miles a day for the second trimester, and about five to six miles during the third.

Most people, of course, will run much less.

“What feels good in one woman’s body isn’t always the same in another woman’s body,” says Watkins. “You might run three miles and walk home. It’s about trying to be flexible with yourself and listening to your body.”

Doctors used to recommend that women keep their heart rate at or below 140 beats per minute during pregnancy, but that guideline is now considered outdated. Most medical professionals today say that women can put in about as much effort as they did pre-pregnancy without any negative impacts on the baby.

That said, as a pregnancy progresses, runners will naturally slow down. An athlete who is used to training at 7:30-per-mile pace may need to work just as hard to run nine-minute miles.

“It’s more of an issue of intensity than overall distance,” says Hoeg. “I generally say [to keep it at a level] that you can have a conversation while you’re running.”


One piece of gear that many pregnant runners say they can’t live without? The belly band.

Many women start wearing these bands, which lift and hold in the growing belly while also supporting the back, in their second trimester. Some say the bands can alleviate round ligament pain, or the aches and jabs women can feel in the lower belly and groin as the uterus expands.

“You just feel more secure running with it,” says Howard, who has had two children. “It was a godsend as far as running down hills.”

RELATED: The Fine Art Of Balancing Running And Parenting

Avoiding Isolation

Many trail runners thrive on finding serene, solitary moments in the woods. But experts say it’s probably best for pregnant runners not to stray too far from civilization—and medical help.

“I do get women contacting me about running races in the middle of nowhere pregnant,” says Hoeg. “I don’t think that’s a great idea to be honest. … You don’t want to be out in the middle of the Gobi desert.”

For longer runs, pregnant runners may want to go with friends, or at the very least carry a cell phone and stay within coverage area in case of an emergency.


A unique consideration outdoorsy pregnant women are facing this summer is Zika. The virus, spread primarily through infected mosquitoes, has been linked to severe birth defects when contracted during pregnancy.

While no one has acquired Zika from a mosquito in the United States yet, experts say it’s likely to be here soon.

“Cover up as much as you can and spray DEET wherever skin might be exposed,” says Esther Han, an OBGYN practicing at a Baltimore hospital.

Pregnancy is a strange, beautiful, at times anxiety-producing, continuously astonishing part of life. When my non-runner friends and family members ask the question I’ve now come to expect—”You’re not still running, are you?” —I not only proudly answer yes, but also add a bit more truth: On many days, the moments I feel best—and truly like myself—are when I’m on the trails. And as I prepare for the many changes that motherhood will bring, that’s something I want to hold on to.

Liana Heitin is a journalist and runner who lives in Washington, D.C. You can find her on Twitter @lianaheitin.

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