Is it safe to use a sauna while pregnant?
By the Find My Sauna team·
Updated ·
7 min read
In Finland, women have kept using the sauna through pregnancy for generations. In the UK and the US, most doctors and midwives advise against it, especially in the first few months. Both sides have their reasons, and they're worth knowing before you decide anything with your midwife.
The short answer
Most health bodies say it's safest to avoid saunas, hot tubs and steam rooms while pregnant, especially in the first 12 weeks. The worry is your core body temperature: a sustained rise to around 39 °C (102 °F) in early pregnancy has been linked to a higher risk of neural tube defects such as spina bifida. Finnish studies found no link between ordinary sauna use and birth defects, but that doesn't prove it's safe for everyone. Talk to your midwife or doctor before you go.
What the official advice says
- NHS (UK). There's little research on saunas, hot tubs and steam rooms in pregnancy. The NHS points to the risks of overheating, dehydration and fainting, particularly in the first 12 weeks, and suggests avoiding places where you could get too hot.
- ACOG (US). The American College of Obstetricians and Gynecologists advises avoiding saunas and hot tubs early in pregnancy, because some studies have linked them, especially long sessions, to birth defects.
- UK Teratology Information Service. Its summary of the research calls the findings mixed, says it isn't possible to confirm sauna use is safe, and suggests that women who carry on limit the time and the temperature.
None of them says a sauna will definitely harm your baby. They're being cautious because the evidence is patchy and the possible harm is serious.
Why heat matters early on
The neural tube, which becomes the baby's brain and spinal cord, forms in the first weeks of pregnancy, often before you know you're pregnant. Animal studies and some human studies suggest that a high body temperature during that window can interfere with it. Researchers usually treat about 39 °C (102 °F) as the level where concern starts. A fever in early pregnancy has been studied for the same reason.
The best-known study, published in JAMA in 1992, followed 23,491 pregnant women in New England. Those who'd used a hot tub in early pregnancy had about 2.9 times the risk of a neural tube defect. For saunas the figure was 2.6, but so few women in the study used one that the result could have been chance.
Hot tubs are the bigger worry
A hot tub heats you faster than a sauna. Your body cools itself by sweating, and sweat can't evaporate when you're sitting in hot water. In a 1981 Canadian study, women in a hot tub at 39–41 °C reached a body temperature of 38.9 °C after 10–15 minutes. None of the women in an 81 °C sauna stayed in long enough to reach 39.9 °C.
That's one reason hot tubs come up more often in the research, and many hot tubs run at around 40 °C (104 °F).
What Finnish studies found
In a 1982 study published in Teratology, Finnish researchers compared mothers of 100 babies with central nervous system defects and 202 with cleft lip or palate against mothers of healthy babies from the same areas. 98.5% of the mothers had used a sauna regularly during pregnancy, and their sauna habits made no difference.
Later work at the University of Turku looked at women in late pregnancy. In a 1991 study, 17 women at 36–37 weeks sat in a sauna at 70 °C for 20 minutes. Their heart rates rose by about 26 beats a minute and their babies' by about 14. The Turku group reported that the babies' heart traces stayed normal during and after the heat, and concluded that healthy women could use the sauna throughout pregnancy. A 2001 review in the American Journal of Medicine took the same view for uncomplicated pregnancies.
Two things to keep in mind. These are mostly women who'd used saunas all their lives, and the 1982 study relied on mothers remembering their habits. So the Finnish results are reassuring, but they aren't the final word.
Later in pregnancy
After the first trimester, the worry shifts from birth defects to you. Pregnancy hormones and extra blood flow to your skin already make you feel warmer than usual. Heat widens your blood vessels and lowers your blood pressure, so fainting is more likely, and a faint on a hot bench or a wet floor can mean a fall. You'll also sweat out fluid you need.
Infrared saunas and steam rooms aren't exempt. We couldn't find any studies of infrared saunas in pregnancy, and your core temperature still rises in one. Our guide to infrared sauna side effects has more.
If your doctor says it's fine
Some doctors, particularly in Finland, are happy for women with healthy pregnancies who are used to saunas to carry on in moderation. If yours agrees:
- keep sessions short, around 10 minutes or less, and sit on a lower, cooler bench
- get out at once if you feel dizzy, sick, too hot or short of breath
- drink water before and afterwards, and see how to stay hydrated in the sauna
- don't go alone, and take care on wet floors and steps
- skip hot tubs, and ask before trying a cold plunge
Our sauna safety rules apply as well, only more so.
If you used a sauna before you knew
This is very common. Neural tube defects are rare, and even in the studies that found a link, the vast majority of women who'd used a hot tub or sauna had healthy babies. Mention it to your midwife or doctor at your next appointment so they can talk it through with you, and don't go back in until you have.
Who should be careful
Everyone who is pregnant should get advice before using a sauna, hot tub or steam room. Be especially careful if you have high or low blood pressure, pre-eclampsia, a heart condition, bleeding, a history of fainting, or a fever. Pregnancy is not the time to start using the sauna for the first time.
This guide is general information, not medical advice.
Spa days during pregnancy
If you're planning a spa day, look for one with warm pools and a quiet relaxation room, and tell the staff you're pregnant when you book. Many spas have their own pregnancy rules.
Woodhouse Spa Buckhead
Atlanta · Spa with a relaxation lounge
QC NY Spa
New York · Spa with outdoor pools
Parkside Spa & Sauna
Washington · Korean-style spa
Frequently asked questions
Can I use a sauna in the first trimester?
Most health bodies, including the NHS and ACOG, advise against it. The first 12 weeks are when a high body temperature is most linked to birth defects. Talk to your midwife or doctor.
Is an infrared sauna safe during pregnancy?
There are no studies of infrared saunas in pregnancy. Your body temperature still rises in one, so the same caution applies. Ask your midwife or doctor first.
Can I go in a steam room while pregnant?
The NHS lists steam rooms with saunas and hot tubs as places where you can overheat and faint. Most advice is to avoid them, especially early in pregnancy.
Is a hot bath safe in pregnancy?
A warm bath is generally fine. Keep it comfortably warm rather than hot, and get out if you feel dizzy or too hot.
Do Finnish women use saunas while pregnant?
Yes, many do, and Finnish studies have not found a link with birth defects. The women studied were mostly used to saunas and had healthy pregnancies, so check with your own midwife or doctor.
