Emily Oster, PhD

2 minute read Emily Oster, PhD
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Emily Oster, PhD

Can I Take a Hot Bath While Pregnant?

Q&A on high temperatures

Emily Oster, PhD

2 minute read

Can you really not take baths when you’re pregnant?

—M

The reason why you may hear not to take a bath during pregnancy is the risk of excessive heat.

In early pregnancy, there is a concern that excessive heat might lead to an increased risk of birth defects. For example: this study (looking at hot tubs) suggests that there might be an increased risk of several gastrointestinal defects. There are also studies that focus on neural tube defects. The mechanism by which excess body heat might impact fetal development in the first trimester is supported in animal models. Some studies show miscarriage risks.

a pregnant adult stepping in the hot bath tub in the washroom
Sora Shimazaki / Pexels

It is important to say that this evidence isn’t from enormous or especially well-designed studies. Most of it comes from “case control” studies that do a lot of different statistical tests, and it’s hard with that type of setup to know if the effects are just showing up by chance.

However, the real concern is about an increase in body temperature to above 101 degrees or so. Hot tubs are typically about 105°, as is Bikram yoga. Spending time working out in a 105° environment can increase your body temperature. But a cooler bath or even a cooler version of hot yoga (some are only 85° or 90°) would be fine. In addition, the neural tube defect concern is limited to the first trimester; by the end of that period, neural tube formation is complete.

On the other end of pregnancy, during labor, baths are a known source of pain relief. So it is not that you can never bathe in pregnancy. The caution is about very hot first-trimester bathing.

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Oui.anny
Oui.anny
3 months ago

I went to Japan on my honeymoon a week after finding out I was pregnant, and was happy to find a lot of new data about the amount of time you spend in hot water battering. You can spend up to 20 minutes in a hot tub or a sauna, so I went to some Onsens while I was in Japan and honestly, I couldn’t stay the full 20 minutes anyway lol. But I felt relieved to see that they had done some good studies on heat and pregnancy. They also included exercise.
https://www.sciencedirect.com/science/article/pii/S1728869X24000625

ParentData Team
ParentData Team
3 months ago

This has been updated on 2/28/25 — thank you for all of the great feedback!

anxiouschillmom
anxiouschillmom
3 months ago

I feel confused by this- doesn’t the neural tube essentially close completely by 5 weeks pregnant? So if the risk is about neural tube closure, wouldn’t it be null after it is closed? Why no baths until the entire first trimester? I’ve been taking warm/ slightly hot baths regularly since then.

-writing this from a now-tepid bath at 11w4days

Bamborghini
Bamborghini
8 months ago

I was surprised at your take here. On other topics you have been such a champion of standing against the scare tactics of ‘maybe it’s bad so better avoid it’ that is so common in pre-natal care. You do caveat that if there is risk it’s just in the first trimester.
As I’m understanding the data on NTD (gastroschisis is most commonly associated) has an odds ratio 2-3 (closer to 1.5 when controlled for women who take a folate containing PNV practically eliminated when controlling for other critical vitamin intake and adequate weight gain in pregnancy). Additionally, this is an incredibly rare disease with prevalence of 3-10 in 10,000 live births. Similar to comparing the absolute v relative risk of co-sleeping, which you did masterfully. To recommend avoiding hot baths (if this is a major component of wellness for someone–like 4 cups of coffee are for you) feels like it’s playing into the same old rhetoric that makes being pregnant feel like a punishment.
Additionally wouldn’t you consider many of the same confounding factors that effect a woman’s desires to drink coffee in the first trimester a factor in the data on neural tube defect and miscarriage? I would argue that women who choose to take more hot baths (even women who have access to a hot tub or whirlpool tub in their home) and who feel well enough to take a hot bath frequently in the first trimester are a fundamentally different group of women then those who do not. I would love to hear your thoughts on this one!
B Thompkins, Family Doc, Santa Fe NM and mother of 6

Jane D
Jane D
6 months ago
Reply to  Bamborghini
6 months ago

Agree! Where is the nuance about the precaution revolving around not wanting to elevate one’s body temperature beyond a certain point, and so any risk being avoidable by simply keeping the water below a certain (quite high) temp? You discussed this in Expecting Better, so I’m surprised to see no mention of it here.

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