Sauna and Pregnancy: Safe, NOT Dangerous (+ 2 False Claims)

Are you (soon to be) pregnant and wondering if you can go to sauna while expecting?

Or maybe you already went to sauna when pregnant, either knowingly or unknowingly, and now your doctor (or worse, the Internet!) tries to guilt-trip you into thinking you harmed your unborn baby?

While that may sound a bit extreme, that’s unfortunately what many women (in English-speaking countries) hear when the topic of sauna and pregnancy comes up.

Even to this day, most (if not all) American health sources say you should avoid saunas during your entire pregnancy:

All this despite lots of research and decades of data saying the opposite:

“Sauna baths are well tolerated and pose no risk to healthy people from infancy to old age, including healthy women in their uncomplicated pregnancy.”

Let’s see what the confusion is about, refute false claims, and cite the most accurate sources you should turn to when thinking about sauna and pregnancy.

Disclaimer: All the pregnant women in the Finnish studies I’m referencing had used traditional saunas, not infrared “saunas” with which no claims can be made due to lack of research.

Sauna and Pregnancy: Poor Sauna Understanding That Led to 2 Major Misconceptions

All the sources saying you shouldn’t go to sauna during pregnancy use the same claims:

❌ your body temperature rises dramatically in the sauna, i.e., you become “overheated” (hyperthermia), which can lead to complications and birth defects such as anencephaly (the fetus missing the largest part of the brain)

❌ when pregnant, the extreme heat of a sauna makes you feel dizzy which could be hazardous for the baby if you fainted as a consequence

What studies actually say:

• Some animal tests have shown that when the mother’s body temperature has risen to 106-107.5 F (41-42 C), her young may be born with defects of the central nervous system (= neural tube defects).

It was quite a stretch to assume that what happens to some animals when their body temperature is equivalent to a dangerously high fever is what happens to human fetuses in a sauna that raises your temperature only very slightly, on average 1.8 F (0.5–1.5 C) degrees during a 15-minute sauna session in a 160-175 F (70-80 C) degree sauna.

✅ So no, sauna has never been shown to cause birth defects.

On the contrary, it has been shown that mothers whose children have a neural tube defect, and mothers with healthy kids, had no difference in their saunaing habits during pregnancy; almost 90% of mothers in both groups had weekly sauna sessions during their entire pregnancy.

✅ In Finland, it’s extremely common for pregnant women to go to sauna throughout pregnancy. Yet, anencephaly is very rare in Finland where its incidence is one of the lowest in the world.

When it comes to “extreme heat” and “overheating” that I see different sources spewing all the time, those are based on poor sauna understanding: the ideal sauna temperature is a lot lower than many English sources claim.

You’re not supposed to feel uncomfortable in a sauna, pregnant or not.

✅ When you’re in a sauna and pregnant, a milder sauna session, both in temperature and in how much water you throw on the sauna rocks (löyly), may be what you naturally gravitate towards.

This is because being pregnant may amplify the effects you would get in a sauna even when not pregnant: your heart rate increases, your circulation improves, and blood pressure drops.

It’s usually not the heat directly that causes dizziness but the fact that your blood pressure has temporarily dropped so much. This is normal and happens to many people even when not pregnant.

If you start to feel dizzy, you should leave the sauna immediately and go sit and rest in a cooler place.

✅ Being pregnant doesn’t necessarily have to change your previous sauna habits at all since studies have found your body adapts to sauna heat:

“Pregnant women adapt well to the thermal stress of the sauna, which is also true of the fetus, provided that it is healthy. […] Healthy pregnant women may safely have sauna baths throughout their pregnancy.”

What about the study with 23,000 women saying sauna and pregnancy is a bad idea?

If you’ve already been fearmongered by your doctor, you may have heard about a study published in 1992, according to which:

“Exposure to heat in the form of hot tub, sauna, or fever in the first trimester of pregnancy was associated with an increased risk for NTDs (neural tube defects).”

What many don’t know is that, despite such strong claims, no association between sauna use and defects was shown.

The researchers interviewed over 23,000 mothers, out of whose children 49 had a neural tube defect. Two of the mothers reported saunaing during the first two months of their pregnancy, while the rest, 47 mothers, hadn’t used a sauna.

According to the researchers themselves, the confidence interval was 0.7–10.1 for saunas specifically, and 0.4–7.9 when accounting for controls too, which is far from impressive.

In plain English this means that intervals this wide are imprecise and suggest a high degree of uncertainty.

Numbers like these were never enough to show a connection between birth defects and sauna use during pregnancy.

As a reminder, already years before it had been shown that saunaing hadn’t caused neural tube defects although the mothers had had regular sauna sessions during pregnancy:

“It is concluded that the relatively mild, temporal hyperthermia caused by the sauna should not be considered hazardous for the developing embryo.”

This research is even more valuable considering it studied 100 mothers whose child had a neural tube defect, instead of just 49 like the 1992 study, and another 100 mothers with healthy kids: almost all moms in both groups (98.5%) had saunaed regularly during pregnancy while the 1992 study had only 2 saunaing mothers.

No differences in sauna habits were found between the two groups, showing there was no link between NTDs and saunaing during pregnancy.

The Final Verdict on Sauna and Pregnancy Given in 2018: It’s Safe

So, can you sauna while pregnant? The answer is yes.

Finally in 2018, even The Irish Times published information that researchers and the general public in Finland had known for decades: sauna and pregnancy is a safe combination.

The University of Exeter wrote about the same study:

The study in question is by the British Journal of Sports Medicine: when the researchers analyzed 12 previous studies, they found that on average, sauna use raised pregnant women’s core temperature to 37.6 C.

That’s a very slight increase in body temperature, extremely far from the risk level found in animal studies, and something that Finnish researchers had shown as early as in 1954 and confirmed again in 1988.

Frequently Asked Questions (FAQ)

1. Are saunas safe during pregnancy?

Yes, traditional saunas that have a wood-burning or electric sauna heater have repeatedly been shown to be safe for pregnant women.

2. Is it safe to go to the red light sauna while pregnant?

Considering that most (or all) sauna and pregnancy studies have been done on traditional saunas, the results of those studies (= saunaing is safe when pregnant) don’t automatically apply to light therapy “saunas.”

They operate differently, haven’t been studied much, and don’t have a long history behind them (= there isn’t much user data available).

If your doctor can’t provide you with any actual studies on the subject, meaning that you’re relying on what the sleazy salespeople have to say about their “saunas,” then it’s not known whether it’s safe or not.

3. Do Scandinavians use saunas when pregnant?

Yes, they do. In Finland, where saunas are most common, 80-90% of expecting women go to sauna regularly throughout pregnancy and stop only when it’s time to give birth.

(In old times, saunas were commonly used for child birth as well, but nowadays children are born in hospitals.)

Research has proven again and again that saunaing is not linked to birth defects, miscarriages, or any other pregnancy complications.

4. Sauna and pregnancy during first, second, or third trimester; does it make any difference with safety?

No, it doesn’t, meaning it’s as safe regardless of the trimester.

According to the British Journal of Sports Medicine that reviewed 12 previous studies:

“Pregnant women can safely engage in […] sitting in hot baths (40°C) or hot/dry saunas (70°C; 15% RH (relative humidity)) for up to 20 min, irrespective of pregnancy stage.”

Final Thoughts

Now that you know sauna and pregnancy together are safe, you can sit back and relax.

And if you had concerns such as “Oh no, I went to sauna before I knew I was pregnant!,” now you know you can calm down as there’s no reason to panic.

If you or your friend is someone who was guilt-tripped by their doctor into thinking that you did something wrong by saunaing while pregnant, I recommend you challenge that doctor’s beliefs and ask where their information is coming from.

After all, there was never a link, not even a weak one, between birth defects and sauna and pregnancy. It was always just a myth, and disproven many times.

To conclude with something more fun, guess what sauna and pregnancy leads to in Finland? It leads to children who, on average, go to the sauna for the first time when they’re only 4 and a half months old! 👶