Hot Baths and Hot Tubs While Pregnant: The Heat Rule

You can take a bath while pregnant, as long as it’s warm and not hot. A hot tub is a different thing, and the advice on those runs from a flat no to a ten-minute limit. The rule behind both is the same: don’t let anything raise your core body temperature. Cleveland Clinic’s ob/gyn puts the bath ceiling at 99 degrees Fahrenheit (37 degrees Celsius). UPMC explains why a tub at home is gentler than a hot tub: a bath “cools down as the minutes go by”, and a hot tub “never cools down.”

Where this post stops

I’m pregnant with my second, it’s November in Ohio, and a bath is the only place my hips stop complaining. I’m not a doctor or a midwife. This post sets out what three sources say about heat and soaking, including where they disagree. It doesn’t recommend anything to put in the water.

The heat rule

The worry is your core temperature, however you get wet. MotherToBaby’s fact sheet on fever and hyperthermia describes overheating as what happens “when the body absorbs more heat than it releases”, and names hot tubs and saunas as possible causes. It says a raised body temperature “can be of concern in early pregnancy, especially if it lasts for a long period of time”, and its bottom line is one sentence: “Hot tub or sauna use during pregnancy should be limited.”

UPMC HealthBeat’s page on hot tubs in pregnancy adds the numbers. A hot tub “can be as high as 104 F”, and “anything that raises your core temperature to over 101 F may harm your growing baby.” It says the risks are “most significant in the first 12 weeks”, when the brain and spinal cord are forming.

Later in pregnancy there’s a second problem. Cleveland Clinic’s hot tub explainer points out that hot water lowers your blood pressure, so “when you stand up, you might feel lightheaded or dizzy — and you could fall or pass out.” So heat matters in the second and third trimesters too.

Baths: warm, not hot

Both health-system pages treat a bath as the answer here. UPMC calls it “the best alternative to a hot tub soak”, and Cleveland Clinic calls a “warm (not hot) bath” a great option. Their reasons:

• It cools. A hot tub has hot water flowing in the whole time. A bath only loses heat from the moment you turn off the tap.
• You set the temperature. Cleveland Clinic’s ob/gyn says: “Your bath should be no higher than 99 degrees Fahrenheit (37 degrees Celsius), which will prevent a rise in your body temperature.”
• No pool chemicals. That’s Cleveland Clinic’s point too.

Ninety-nine degrees is about body temperature, so it feels warm, not steamy. If your skin goes pink or you start to sweat, the water is too hot.

Cleveland Clinic’s own suggestion for checking is one I liked: buy the baby bath thermometer now. “A reliable thermometer can give you assurance that your bath is a safe temperature.” A floating one like the Dreambaby duck bath thermometer will go on to do the same job in the baby tub.

UPMC’s bath rules, in its own words:

• “Keep your shoulders and arms out of the bath. This can help you avoid getting overheated.”
• “Make sure your tub has a no-slip pad in the bottom.” Your balance is off and tubs are slippery. Mine is a plain suction-cup mat like the Gorilla Grip bathtub mat.
• Keep the water plain. UPMC says bath additives “could irritate your genital area.”

Getting out is my own addition. Sit on the edge for a few seconds before you stand, and keep a hand on something solid. Cleveland Clinic’s fainting warning applies to any hot water.

Hot tubs: where the sources split

The two health systems don’t say the same thing here, so I’ll give you both.

Cleveland Clinic says no. Its ob/gyn is flat about it: “Hot tubs are not safe during pregnancy.” She says the same of saunas, steam rooms and hot yoga: “Anything that’s designed to heat you up” isn’t safe.

UPMC says most experts “don’t expressly forbid” it. It adds that the American College of Obstetricians and Gynecologists recommends against it, and that it’s “best to err on the side of safety”. For anyone who goes in anyway, it lists precautions:

• “Use a hot tub or sauna for no more than 10 minutes.”
• “Set the water (or sauna) to a lower temperature than normal.”
• “Sit in the hot tub with your arms and chest out of the water.”
• Get out “if you start feeling dizzy, have pain, or your hands or feet tingle.”

Both agree on the feet. Cleveland Clinic says it’s “generally safe to put your feet in a hot tub when you’re pregnant”, because soaking your lower legs “isn’t likely to raise your core body temperature.” UPMC offers the same compromise.

So at the hotel pool or your in-laws’ deck this winter, the cautious reading of all three sources is to sit on the edge with your feet in. If you want more than that, ask your OB what they’re comfortable with for your pregnancy.

If you were in a hot tub before you knew

UPMC covers this directly: “it’s unlikely you harmed your developing baby. But if you have doubts or would like reassurance, call your ob-gyn.” MotherToBaby’s phrasing is that studies have reported “a small chance” of certain birth defects with high body temperature very early in pregnancy. It’s worth mentioning at your first appointment. Don’t lose a week of sleep over it.

Other ways to get warm and comfortable

• Local heat. A wrapped heating pad on a sore back warms one patch of you, not all of you. The rules are in can you use a heating pad while pregnant.
• Swimming. UPMC suggests it “for a similar feeling”, because the water holds your weight.
• Pillows. If the bath is really about your hips, the setup in how to sleep when pregnant does more for them than hot water does.

When to call your OB or midwife

• You feel dizzy, faint or unwell after getting hot, and it doesn’t pass once you’ve cooled down and had some water. UPMC warns that overheating can leave you dehydrated.
• You fell getting in or out. Cleveland Clinic says to contact your provider after any fall in pregnancy, and “if in doubt, play it safe and get immediate medical care.”
• You have a fever. MotherToBaby says to talk with your healthcare providers about how to treat it.
• You want reassurance about a hot tub or sauna early on. That’s a normal phone call to make.

One labor-shaped note: UPMC says not to take a bath after your water breaks. Everything about that stage belongs to Tales of a New Mom’s guide to the early signs of labor and to your maternity unit’s phone line.

FAQ

How hot can a bath be when pregnant?

Cleveland Clinic’s ob/gyn says no higher than 99°F (37°C). That’s the only bath figure in the sources I loaded. UPMC just says warm, not hot, with your shoulders and arms out.

Can I use a hot tub in the third trimester?

Cleveland Clinic says hot tubs are “still not a good idea” later on, because of dizziness and falls. UPMC allows a short, cooler soak of no more than 10 minutes with your chest out of the water. Ask your own OB.

Is a hot shower okay?

None of the three sources gives a rule for showers. The same principle applies: if you come out flushed, dizzy or sweating, it was too hot for too long.

Are saunas and steam rooms different from hot tubs?

No, they fall under the same advice. MotherToBaby says sauna use “should be limited”, and Cleveland Clinic says saunas are “double bad news” because they also dehydrate you.