First-trimester exhaustion: Why pregnancy feels like running a marathon

Pregnancy may look like a picture postcard, glowing skin, cute bump, and all smiles, but behind the scenes, it can feel very different. There may be days when all you want to do is hit the pillow and melt into the couch, no matter how much sleep you got last night. You’re not lazy or doing anything wrong; first-trimester exhaustion is very real.

That bone-deep tiredness that seems to come out of nowhere? It’s your body’s way of saying, “Hey, I’m doing a lot right now.” In fact, experts say early pregnancy can feel a lot like running a marathon, only that it’s minus the sneakers here.

Let’s unpack what’s really happening inside your body, why you feel so wiped out, and how to make it through this phase with a little more grace and a lot more rest, with insights from Rachel Miller, Obstetrician and Gynecologist at Atrium Health.

What causes first-trimester exhaustion?

Those early pregnancy signs can sneak up on you fast, sometimes as soon as a week after conception. One day you’re powering through your to-do list, and the next, getting out of bed feels like climbing a mountain. 

And if you’ve been wondering, “Why am I this tired when I haven’t even done anything?”, here’s the truth: you kind of have. According to research published in Science Advances in 2019, the energy demands of pregnancy are on par with those of elite endurance athletes. Yep, being pregnant is basically like running a marathon, just without the medal or the sneakers.

Every minute of your first trimester, your body is hard at work behind the scenes, building a brand-new organ (the placenta!), ramping up blood volume, creating new tissue, and balancing a surge of hormones. It’s putting in serious overtime, even when you’re just sitting still. So yes, your body is training for a marathon, it’s just one you can’t see from the outside.

Why does pregnancy fatigue feel so different from normal tiredness?

You know that tired feeling after staying up too late or squeezing in a tough workout? First-trimester fatigue just laughs at that kind of tired. This isn’t the kind of exhaustion a nap or a smoothie can fix. It’s a deep, all-over tired, the kind that seeps into your bones and makes even the smallest task feel monumental.

And it totally makes sense. Your body is juggling so much right now, massive hormonal changes, higher energy demands, and nonstop adjustments to support your growing baby. That’s a full-time job all on its own. So if folding laundry feels like climbing Mount Everest, trust me, you’re not imagining it.

Dr. Rachel Miller explains it best, “I’ve never run a marathon, but I have been pregnant. (The furthest I’ve run is six miles.) Fatigue hits everyone differently. Some people handle it more easily, but for others, it really can feel like running a marathon.”

How long will this “marathon” phase of fatigue last?

The good news? This season of all-day tiredness doesn’t last forever. Most parents-to-be start noticing their energy return around the end of the first trimester. Around weeks 13–14, many find they can finally make it through the day without crashing mid-afternoon (or mid-Zoom call).

Think of the second trimester as your “runner’s high” moment, a burst of energy before you head into the home stretch later on.

How to recharge when you’re running on empty? 

Here’s the truth: you can’t outsmart pregnancy fatigue. But you can make small adjustments to help your body recharge and cope.

• Snack often. Eat small, frequent meals that combine protein and complex carbs, like yogurt and fruit, or hummus with whole-grain crackers, to keep your blood sugar steady.
• Sip, sip, sip. Dehydration can sneak up fast, especially if you’re battling nausea. Keep a water bottle handy.
• Move gently. A slow walk or a few prenatal yoga stretches can actually boost circulation and energy levels.
• Nap without guilt. If your body’s asking for rest, listen. A 20-minute nap can make all the difference.

Dr. Miller adds, “Small, frequent snacks, staying hydrated, and gentle exercise like walking can give you more energy. Don’t forget about the power naps during lunch break!” Remember: your body isn’t being lazy, it’s being wise.

How do you balance work, family, and extreme tiredness?

If you’re trying to juggle work deadlines, family responsibilities, and a growing baby, all while barely keeping your eyes open, you’re already doing your best. This phase can test even the most organized parent.

Give yourself permission to let go of the “extras.” The vacuuming can wait. Dinner can come from a takeout box. And if you need to close your eyes on the couch at 7 p.m.? Go ahead, do it.

Dr. Miller’s advice is spot on: “This is tough! I tell my patients that they have to set boundaries and establish what is non-negotiable. Forget about the ‘extra stuff’ for now. Don’t feel guilty for take-out for dinner or letting the laundry go an extra week. All that is fine.” Pregnancy is not the time to prove you can ‘do it all.’ It’s time to slow down, let go, and focus on what really matters: your health and your baby.

When to call your doctor about fatigue

Feeling wiped out is a hallmark of early pregnancy, and most of the time, it’s completely normal. Your body is working overtime, building the placenta, ramping up blood volume, and managing a whirlwind of hormones, so some exhaustion is expected.

But sometimes, fatigue can be a sign of something else, like anemia, thyroid issues, or even mood changes. Trust your instincts: if something feels off, it’s worth checking in with your provider.

Dr. Miller advises, “If the fatigue is paired with shortness of breath, rapid heartbeat, or chest pain, dizziness, pale or grayish colored skin, or if there are mood changes associated with the fatigue. These are indications that there may be something else going on. Be sure to address these with your physician or midwife.”

When in doubt, it’s always better to get checked. Your provider can make sure there’s no underlying issue and help you find safe ways to boost your energy, so you can feel a little more like yourself while growing a tiny human.

Conclusion

Your body is running one of the most intense endurance events there is, and you’re doing it 24/7, often without visible medals or finish lines. So if you need extra rest, naps, or slower mornings, take them.

You’re not weak. You’re growing a human. And that’s the most powerful kind of strength there is. The first trimester may feel like a marathon, but remember: this race ends with the ultimate prize, a healthy baby (and hopefully, some second-trimester energy waiting for you at the finish line).

You may also like

• 5 natural remedies for insomnia during pregnancy (that actually work)
• Ectopic pregnancy: What it is and what you can do about it
• What to ask your doctor when pregnant?

Sources

1. Maximum sustained energy expenditure limits in humans. Proceedings of the National Academy of Sciences (PNAS). 2019. “Extreme events reveal an alimentary limit on sustained human metabolic scope.” (https://pmc.ncbi.nlm.nih.gov/articles/PMC6551185/) 
2. Physiological adaptations during pregnancy. Cardiovascular Journal of Africa. 2016. “Physiological changes in pregnancy.” (https://pmc.ncbi.nlm.nih.gov/articles/PMC4928162)