Saunas and Hot Tubs in Pregnancy: Complete Guide
That post-workout sauna or relaxing hot tub soak is one of the small pleasures many people put on hold once they're expecting. It's not just an old wives' tale — there's a genuine medical reason UK health guidance advises against them, and it comes down to how your body handles heat.
Why raised core temperature matters
Your core body temperature naturally sits around 37C. Prolonged exposure to heat sources that push it above roughly 39C is associated with an increased risk of neural tube defects when this happens during the first trimester, the period when your baby's brain and spinal cord are forming. Saunas, hot tubs, steam rooms, and hot yoga classes can all raise your core temperature quickly, especially because immersion in hot water heats you faster than sitting in hot air. This is why NHS guidance recommends avoiding them throughout pregnancy, not just in the first 12 weeks.
What to avoid and why
- Hot tubs and jacuzzis — water temperature plus immersion raises your core temperature faster than almost anything else, and many public hot tubs also carry a higher risk of picking up an infection.
- Saunas and steam rooms — dry or wet heat over an extended session has the same overheating effect, even without water immersion.
- Hot yoga or heated studio classes — the combination of a heated room and exertion makes overheating more likely than in a normal-temperature class.
- Very hot baths — a bath that's uncomfortably hot to the touch, or one you soak in for a long time, can also push your temperature up, even though a bath alone rarely reaches sauna-level heat.
Safer ways to relax and stay warm
- A warm bath (not scalding hot — if it's uncomfortable to keep your hand in, it's too hot) is generally considered fine for a normal soak.
- Swimming is one of the best forms of exercise in pregnancy, as the water supports your bump and body weight while keeping you cool.
- Gentle, non-heated yoga or stretching classes give you similar relaxation benefits without the overheating risk.
- If you've been in a sauna or hot tub before you realised you were pregnant, try not to worry — a single brief exposure carries a low risk, and the key is avoiding it going forward.
When to seek advice
If you do start to feel very hot, dizzy, faint, or unwell after any activity in pregnancy, get out of the heat, cool down, drink water, and rest. Contact your midwife or GP if symptoms don't settle quickly, or call 111 if you feel seriously unwell.
Frequently Asked Questions
Can I use a hot tub when pregnant?
It's best to avoid hot tubs throughout pregnancy. They raise your core body temperature quickly through water immersion, which in early pregnancy is linked to a higher risk of neural tube defects, and shared hot tubs can also carry a higher infection risk. Warm (not hot) baths are a safer alternative.
Are warm baths safe in pregnancy?
Yes, a warm bath at a comfortable, non-scalding temperature is generally considered safe throughout pregnancy. The guidance to avoid is very hot bathwater or long soaks that push your core temperature up in the same way a hot tub or sauna would.
What if I used a sauna before I knew I was pregnant?
Try not to panic. A single, brief exposure to sauna or hot tub heat before you knew you were pregnant carries a low risk, and most pregnancies continue completely normally. The important thing is to avoid saunas, hot tubs, and steam rooms from now on. If you're worried, mention it to your midwife at your next appointment for reassurance.
This article is for informational purposes only and does not constitute medical advice.
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