The short answer

The NHS advises being careful in saunas, steam rooms and hot tubs in pregnancy because of the risks of overheating, dehydration and fainting, and says it's best to avoid places where you might get too hot, especially in early pregnancy. Some research suggests short, moderate sessions are low risk, but UK advice favours caution.

On this page
  1. What does the NHS say?
  2. What does the research show?
  3. What should you do?
  4. Common questions
  5. References

What does the NHS say?

The NHS notes that there is little research on saunas, steam rooms and hot tubs in pregnancy. Its concern is that they could make you overheat, become dehydrated or faint, and it suggests avoiding places where you might get too hot, such as steam rooms and hot tubs, which can reach 40°C. Raised core temperature is of most concern in the first trimester.

What does the research show?

There is more nuance than the headline advice suggests:

  • A 2019 systematic review from the University of Sydney looked at studies of heat in pregnancy. The authors concluded that pregnant women could probably sit in a hot bath up to 40°C or a dry sauna at up to 70°C and 15% humidity for up to 20 minutes without their core temperature rising above the level of concern. These were short, controlled exposures.
  • A Finnish study from 1991 gave 23 healthy women at 36 to 37 weeks of pregnancy a 20-minute sauna at 70°C. It didn’t trigger labour. The babies’ heart rates and movements rose a little and returned to normal, and all were born in good condition.
  • In Finland, sauna use during pregnancy is common and long-established. That is often quoted as reassurance, but it hasn’t been studied in a way that proves safety.

The concern is about the developing baby when the mother’s core temperature rises well above normal, as it can in a fever, or in a long or very hot session.

What should you do?

  • Follow UK advice and your midwife. If in doubt, give saunas, steam rooms and hot tubs a miss, especially in the first trimester.
  • If you do use one, and your midwife is happy, choose a milder sauna, sit on a lower bench, keep it short (under 15 minutes), drink plenty and leave at the first sign of feeling hot, dizzy or unwell.
  • Skip steam rooms and hot tubs, which heat you faster.
  • Avoid cold plunges and open-water dips unless your midwife says otherwise.

Keep reading

Common questions

Is a sauna safe in the first trimester?

The first 12 weeks are when raised body temperature is of most concern, because a high core temperature in early pregnancy has been linked with a higher risk of some birth defects. UK advice is to avoid activities that might make you overheat during this time.

Can I use a steam room or hot tub when pregnant?

The NHS suggests avoiding them, because they can raise your body temperature quickly. Hot tubs can be as hot as 40°C.

What if I used a sauna before I knew I was pregnant?

Try not to worry. A short sauna is unlikely to have raised your core temperature much. If you're concerned, talk to your midwife or GP.

References

  1. NHS. Is it safe to use a sauna or Jacuzzi if I'm pregnant?nhs.uk
  2. Ravanelli N et al. Heat stress and fetal risk. Environmental limits for exercise and passive heat stress during pregnancy: a systematic review with best evidence synthesis. British Journal of Sports Medicine, 2019.pubmed.ncbi.nlm.nih.gov
  3. Vähä-Eskeli K, Erkkola R. The effect of short-term heat stress on uterine contractility, fetal heart rate and fetal movements at late pregnancy. European Journal of Obstetrics, Gynecology and Reproductive Biology, 1991.pubmed.ncbi.nlm.nih.gov
  4. NHS. Exercise in pregnancy.nhs.uk

First published 4 November 2026. Spotted an error? Tell us and we'll correct it. Read our editorial policy.