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The short answer is that using a hot tub during pregnancy is not banned outright, but it depends on two numbers and on one person. The two numbers are water temperature and how long you stay in. The person is your doctor or midwife, who knows how your pregnancy is going and has the final word: without their explicit approval, our own safety sheet lists pregnancy among the conditions that rule out using the tub.
What I can give you is the data, because that is usually the part missing from the discussion. I'll walk you through what the research measured about core body temperature, why the earliest weeks are different from the rest, and which conditions make one soak genuinely different from another. With those in hand, the conversation with your doctor becomes a precise question rather than a vague worry.
What the research actually measured
The concern in pregnancy is not the hot tub itself: it is hyperthermia, meaning a rise in your core body temperature. The threshold treated as critical in the literature is 39 °C of core temperature, not water temperature.
There is a systematic review on exactly this, published in the British Journal of Sports Medicine (Ravanelli et al., 2019, 53(13):799-805), pooling 12 studies covering 347 pregnant women exposed to heat in various forms. The result: no woman exceeded 39 °C. The highest individual reading was 38,9 °C, and it came from land based exercise, not from water.
Mean end of trial core temperatures, by activity:
- land based exercise: 38,3 °C
- sauna: 37,6 °C
- water based exercise: 37,5 °C
- hot water bathing: 36,9 °C
Hot water bathing is the lowest entry on that list, which is worth knowing if you have been told it is the riskiest thing you could do.
But that 36,9 °C has to be read together with the conditions it was measured under, otherwise it turns into permission the study never granted: the baths in those studies were at water temperatures no higher than 40 °C, and immersions did not exceed 20 minutes. The finding says that within those limits the critical threshold is not reached. It says nothing about an hour at 40 °C, which is a different situation and was never measured.
Why two reputable sources give different numbers
Search in English and you will find recommendations more cautious than that 36,9 °C, and you should know why. The American College of Obstetricians and Gynecologists advises against letting core temperature rise above 38,9 °C, and the most widely used clinical guidance translates that threshold into water below 37,8 °C and soaks of around 10 minutes. The NHS goes further, advising that anything which significantly raises core temperature is best avoided in pregnancy, particularly in the first twelve weeks, while stating plainly that little is known about the safety of saunas and hot tubs in pregnancy.
These positions do not contradict each other: they answer different questions. The 2019 review measures what happens to core temperature under controlled conditions. Clinical guidance sets a safety margin for the general population, where nobody is measuring anything and a tub can sit at 40 °C without you knowing.
When two serious sources diverge, the sensible move is to stand with the more cautious one. In practice that means warm rather than hot water, short soaks, and no improvising.
Why the earliest weeks are different
This is the point general articles skip most often. The risk linked to hyperthermia is not spread evenly across nine months: it concentrates in the very first weeks, while the neural tube is closing.
The hyperthermia fact sheet from MotherToBaby, a service of the Organization of Teratology Information Specialists, is precise about this: several studies have reported a small chance of neural tube defects in babies of people who had fever or hyperthermia before the sixth week of pregnancy, while high body temperatures occurring after the sixth week are not expected to increase that chance. The same sheet recommends limiting hot tub and sauna use during pregnancy.
You will find the same reasoning applied to a neighbouring topic in the guide on hot tub benefits and contraindications, where the conditions that rule out a soak are listed one by one.
The conditions that change everything: temperature, time, jets
One soak is not the same as another, and the variables that matter are few and measurable.
Water temperature. This is the main one. Below 37 °C the water sits close to body temperature and your body is not forced to shed excess heat. At 40 °C, the maximum our safety sheet allows for a healthy adult, the picture changes and safe durations shorten considerably.
Duration. The studies above work with immersions within 20 minutes, the American guidance with around 10. Either way we are talking minutes, not hours, and one soak at a time.
Jet position. This one comes from mechanical common sense rather than the literature: a jet aimed straight at your abdomen has no reason to be there. On a hot tub the jets are directional, so point them at your back, legs and feet, which is where you want them anyway.
Getting in and out. With your centre of gravity shifted forward, the step into a tub is the critical moment. A handrail, a step and someone giving you a hand matter more than any feature of the machine.
Saunas and steam rooms are a different question
Worth separating these out, because they usually arrive inside the same question. Saunas and steam rooms work at far higher ambient temperatures, between 45 and 90 °C depending on the type, and they do it in air: your body sheds heat differently than it does in water. In the 2019 review the sauna still stays below the critical threshold, but it starts from a higher mean than hot water bathing.
Current advice in pregnancy is to avoid them, and that recommendation is firmer than the one about soaking in warm water. If you are weighing up both, they are two separate questions for your doctor, not one.
Can you give birth in a hot tub?
No, and here the answer is unambiguous: a hot tub is not a birth pool, and the two are not interchangeable.
The reason is the plumbing. Hospital protocols on the use of water in labour and birth, written on the basis of NICE guidance, explicitly exclude recirculating systems, spa style jets, pumped heating and whirlpool features from birth pools: they add pipework, pumps, valves and hidden wet areas that are hard to clean to the standards agreed with infection control. A birth pool is designed the opposite way, with as few joints and fittings as possible. A hot tub with 40 or 92 jets is precisely what those protocols rule out.
There is a second point that bears directly on home use: the same protocols advise against filling a birth pool and keeping it warm in anticipation of labour, because of the risk of Legionella pneumophila in water held at temperature by a pump or heater. A hot tub is, by design, water kept warm and recirculating for weeks at a time.
Then there are the clinical parameters, which no domestic product supports: water checked regularly and kept around 37 °C, sufficient depth, fetal heart rate monitoring with waterproof probes, agreed cleaning protocols and trained midwifery staff. Water birth is an assisted procedure, not an environment you can buy.
If you are considering a water birth, the people to talk to are your maternity unit or your midwife, and the pool is theirs.
If you already own the tub
Once your doctor has cleared you to use it, the rest is ordinary management and it mostly comes down to the water. A domestic hot tub runs on treated, recirculated water, so its quality depends on how you maintain it: correct sanitiser levels, a clean filter, no old standing water. The water treatment procedure from our technical support covers the steps and the intervals.
As for temperature, set the thermostat and check it before you get in rather than judging by hand: it is the one number you can genuinely control, and it is the one that matters most.
Which tub, if this is the reason
If you are weighing up a purchase right now, the feature you need is not power. What counts is easy entry and exit, a low profile, precise temperature control and jets you can direct away from your abdomen.
The BL-837 hot tub measures 168 by 209 centimetres with a height of 88, with 40 jets and 3 seats: it is among the most compact, and the low rim makes getting in simpler. The BL-862 is smaller still, 160 by 160 centimetres with 23 jets, if space is tight.
A high jet count is not an advantage here: it means more active massage, not more comfort. If what you need is to sit in warm water for twenty minutes, a compact model with directional jets serves you better than a more powerful one.
Frequently asked questions
Can you use a hot tub while pregnant?
It is not banned outright, but it needs your doctor's explicit approval. The available data indicate that a hot bath within 40 °C and 20 minutes keeps core temperature below the critical threshold of 39 °C, with a measured mean of 36,9 °C. American guidance is more cautious and points to water below 37,8 °C for around 10 minutes.
What is the right water temperature?
The more cautious recommendations point to staying below 37,8 °C, so warm rather than hot. Set the value on the thermostat and check it before getting in rather than estimating by hand.
Is the first trimester different?
Yes, and it is the period calling for the most caution. According to MotherToBaby the neural tube defect risk linked to hyperthermia concerns high temperatures before the sixth week, and is not expected to be raised after that; the NHS still advises caution throughout the first twelve weeks. This is the stage where your doctor's opinion counts most.
What about the third trimester?
The concerns tied to organ development do not apply at that stage, but the circulatory and practical ones remain: drops in blood pressure, difficulty getting in and out, the need to keep soaks short. Here too the judgement is your doctor's.
Can a hot tub bring on contractions?
It is a claim that circulates widely and that I have not found supported by evidence in the literature, but it is not something I can rule out for you either: it is a clinical question, and it belongs with whoever is looking after your pregnancy.
Can I give birth in my hot tub at home?
No. Hospital protocols exclude jetted, recirculating and pump heated systems from birth pools on cleaning grounds, and water birth requires midwifery care and monitoring. It is a procedure, not an environment.
Do saunas and steam rooms count the same?
No, they are hotter and current advice is to avoid them in pregnancy. Treat them as a separate question.
What to do, in order
- Put the question to your doctor or midwife before you get in, and bring the numbers with you: the water temperature you intend to use, the duration, how many weeks along you are. A precise question gets a precise answer.
- If you are cleared, set the thermostat to warm water, staying below the 37,8 °C the more cautious guidance points to, and check it before getting in.
- Keep the soak short, in the range of 10 to 20 minutes, and one at a time.
- Point the jets at your back, legs and feet, never at your abdomen. Have someone help you in and out.
- Get out immediately if you feel dizzy, notice your heart racing or feel excessively hot, and do not go back in that day.
The most common mistake is treating the matter as settled because some general source said it was fine. The conditions matter more than the yes or no: the same immersion at 36 °C for ten minutes and at 40 °C for half an hour are two different things, and only the first is covered by the data above.
If you are considering a purchase and want to know which model is easier to manage, our customer service can answer on the technical side. Not on the medical side: that stays with your doctor. Who we are and the experience behind this guide is on the about us page, and warranty conditions are in the sales terms and conditions.
Sources: Ravanelli N. et al., Heat stress and fetal risk, British Journal of Sports Medicine 2019;53(13):799-805 · ACOG, Exercise During Pregnancy · MotherToBaby, Fever / Hyperthermia · NHS hospital protocols on the use of water in labour and birth, based on NICE guidance.
Catalogue figures in this guide (dimensions, jets and seats) are read from the product pages and update with the catalogue: what you see is the current value. Information on temperatures, durations and the safety of immersion during pregnancy is provided for general information and does not replace medical advice in any way: our safety sheet lists pregnancy among the conditions that rule out use without explicit medical approval, and every pregnancy follows its own course, which only the people looking after it can assess. Talk to your doctor before using a hot tub.
