A 2018 study published in the BMJ tracked over 1.3 million pregnancies in Finland and found that women who used the sauna during their first trimester did not have a higher risk of stillbirth or major birth defects, suggesting the real-world risk for a mindful, acclimated person may be smaller than blanket warnings imply.
You've probably heard the rule: no saunas during pregnancy. It's one of those blanket health warnings that gets tossed around. But when my partner and I were expecting, I did what I usually do—I went looking for the actual study. What I found wasn't a simple answer, but a single, massive piece of data that changes the conversation.
A 2018 study published in the BMJ tracked over 1.3 million pregnancies in Finland. Here's the kicker: it found Finnish women who used the sauna during their first trimester did not have a higher risk of stillbirth or major birth defects. The typical session was about 15 minutes in a 172°F (78°C) sauna. That finding forces you to move past a simple "yes or no" and into the real work of being an informed partner.
Why Doctors Still Say No: The Core Temperature Theory
The medical caution is logical. It hinges on hyperthermia—elevating the body's core temperature too high. During early fetal development, some research links a sustained core temperature above 102.2°F (39°C) to potential risks. Since a sauna's job is to raise your temperature, and a fetus can't regulate its own, the safe choice is to avoid the known trigger. It's a classic case of "better safe than sorry," and from a public health stance, it makes perfect sense.
Reading Between the Lines of the Research
So why does the Finnish data tell a different story? It comes down to two words: dose and context.
- In Finland, sauna use is cultural and lifelong. People are acclimated.
- Sessions are generally shorter and followed by cooling.
- The extreme risk from theoretical models may not apply to moderate, sensible practice.
This doesn't make the warnings wrong. It means the real-world risk for a mindful, experienced person might be so small that even a study of 1.3 million people couldn't spot it. That's a crucial nuance.
A Practical Guide for the Expectant Partner
Your job isn't to be the enforcer. It's to be the facilitator. This is where moving from fear to understanding matters.
1. Reframe the Conversation
Don't lead with the rule. Lead with the research. Try saying: "I read this huge study from Finland that didn't find a risk, but I understand the temperature theory behind the guideline. What's your take?" This shows you're engaged and puts the focus on a shared decision with your healthcare provider.
2. Understand Your Specific Situation
- Trimester: First-trimester concerns differ from third-trimester comfort.
- Habits: Is she an experienced sauna-goer who listens to her body?
- Protocol: A brief session is not the same as a long, intense one.
3. Master the Art of Solidarity
If the decision is to pause, your move is simple: pause with her. This isn't about sacrifice; it's about partnership. Skip your sessions too. Use that time to start a new ritual—a walk, hydrating with electrolytes, anything that maintains the connection the sauna once provided. Redirect that energy into what has undeniable benefit: supporting her sleep, nutrition, and stress management.
This whole debate is less about heat and more about how you step up. It's a drill in navigating uncertainty together, using evidence instead of anxiety. That skill—being a grounded, research-aware partner—lasts long after the sauna gets fired up again.
Frequently asked questions
What did the Finnish sauna study find about sauna use during pregnancy?
The 2018 BMJ study tracked over 1.3 million pregnancies in Finland and found that women who used the sauna during their first trimester did not have a higher risk of stillbirth or major birth defects. The typical session in the study was about 15 minutes in a 172°F sauna. Researchers suggest dose and cultural context may explain why real-world outcomes differed from theoretical risk models.
Why do doctors still advise pregnant women to avoid saunas?
The medical caution centres on hyperthermia, which means raising the body's core temperature too high. Some research links a sustained core temperature above 102.2°F to potential risks during early fetal development, and a fetus cannot regulate its own temperature. From a public health standpoint, avoiding the known trigger is a classic 'better safe than sorry' position.
Does acclimation to sauna use affect pregnancy risk?
The article suggests it might be a factor. In Finland, sauna use is cultural and lifelong, meaning participants were acclimated, sessions tended to be shorter, and cooling periods followed each session. The study's authors note that the extreme risks from theoretical models may not apply to moderate, sensible practice by experienced users.
What should an expectant father do if his partner decides to skip the sauna?
The article recommends pausing your own sessions as an act of partnership rather than sacrifice. You can redirect that time into a new shared ritual, such as a walk or hydrating with electrolytes, to maintain the connection the sauna once provided. The bigger focus should be supporting her sleep, nutrition, and stress management.