Pregnancy brings a tidal wave of questions about what's safe and what isn't, and for women who love their sauna routine, one of the first is almost always the same: can I still use my sauna?
The answer isn't as black and white as most articles on the internet would have you believe. Depending on where you look, you'll find everything from "absolutely not, ever" to Finnish mothers insisting they saunaed happily through all nine months without a single complication. The truth, as it usually does, falls somewhere in between — and understanding the nuances can help you make an informed decision with your healthcare provider rather than relying on fear or hearsay.
Below, we'll walk through the actual research on sauna use during pregnancy, what the major medical organizations recommend, how different types of saunas affect risk, what each trimester looks like from a safety standpoint, and what alternatives you can turn to when the heat needs to take a back seat.
Why Heat Exposure During Pregnancy Raises Concerns
The core issue with sauna use during pregnancy isn't the sauna itself — it's hyperthermia, or an abnormal rise in your body's core temperature. Under normal circumstances, your body regulates heat efficiently through sweating, increased blood flow to the skin, and other cooling mechanisms. During pregnancy, however, the stakes change dramatically because a developing fetus cannot regulate its own body temperature independently. The fetus relies entirely on the mother's thermoregulatory system, and when maternal core temperature rises too high, it can directly affect fetal development.
Animal studies dating back nearly a century have demonstrated that sustained maternal hyperthermia during early gestation can cause a range of birth defects, with the brain and central nervous system being particularly vulnerable. Research on rodents, guinea pigs, and other mammals suggests that a core temperature increase of approximately 1.5°C to 2°C above baseline — equivalent to reaching about 39°C (102.2°F) in humans — represents the threshold above which teratogenic (birth defect–causing) effects begin to appear.
In humans, the primary concern has centered on neural tube defects (NTDs) — a category that includes conditions such as spina bifida and anencephaly. A widely cited 1992 study published in JAMA followed a cohort of over 23,000 women and found that exposure to heat sources like hot tubs, saunas, or fever during early pregnancy was associated with roughly double the risk of NTDs. A subsequent 2005 meta-analysis in Epidemiology, which pooled data from 15 studies covering more than 1,700 NTD cases, found an overall odds ratio of 1.92 — meaning women who experienced hyperthermia in early pregnancy had approximately twice the baseline risk of having a baby with an NTD.
Beyond neural tube defects, some studies have also pointed to potential associations between maternal hyperthermia and heart defects, oral cleft abnormalities, and miscarriage, though the evidence for these outcomes is less robust.
It's important to put these numbers in context: neural tube defects are already quite rare, affecting roughly 1 in 1,000 pregnancies in the United States. Even a doubled relative risk still represents a small absolute risk. That said, when a risk is avoidable and the downside is a serious birth defect, most medical professionals — and most expecting mothers — prefer to err on the side of caution.
What Major Medical Organizations Recommend
The American College of Obstetricians and Gynecologists (ACOG) advises pregnant women to avoid activities that can raise their core body temperature above 102.2°F (39°C). ACOG does not issue an outright ban on sauna use but strongly recommends caution, particularly during the first trimester when organ formation is occurring.
The Centers for Disease Control and Prevention (CDC) echoes this guidance, advising pregnant women to avoid saunas, steam rooms, and hot tubs — especially in early pregnancy.
Kaiser Permanente's clinical guidelines take a more permissive approach: they note that experts do not forbid sauna use during pregnancy but recommend limiting sessions to no more than 15 minutes and exiting immediately if you feel overheated or uncomfortable.
The Organization of Teratology Information Services (OTIS), now known as MotherToBaby, notes that a maternal body temperature of 101°F (38.3°C) or above can raise concerns during pregnancy and recommends limiting hot tub and sauna exposure, particularly in the first trimester.
In short, the prevailing medical consensus in the United States and most Western countries is cautious: sauna use isn't absolutely prohibited, but it's considered safest to avoid it — or to limit exposure significantly — during pregnancy.
The Finnish Perspective: A Different Cultural Lens
Any honest discussion of this topic has to acknowledge Finland, a nation of 5.5 million people and an estimated 3.3 million saunas. Sauna bathing is so deeply woven into Finnish culture that it would be virtually impossible to conduct the kind of controlled study that Western medical guidelines often demand — nearly everyone uses saunas, including pregnant women.
And that's exactly what the data from Finland shows. Studies of Finnish women's sauna habits during pregnancy have consistently found that the vast majority — upwards of 90% — continue to sauna regularly throughout all three trimesters, typically stopping only when labor begins. Despite this near-universal exposure, Finland does not have elevated rates of neural tube defects or other birth defects associated with hyperthermia. In fact, NTDs are quite rare in the country.
A Finnish study published in Teratology (1982) specifically investigated this question by comparing 100 mothers whose babies had central nervous system malformations with 100 mothers of healthy babies. The researchers found no differences in sauna habits between the two groups — in both cases, approximately 98.5% of mothers had used the sauna regularly during pregnancy.
This doesn't mean sauna use during pregnancy is risk-free — it means that the risk, in the context of traditional Finnish sauna practice (which typically involves moderate temperatures around 70–80°C and sessions of 15–20 minutes), appears to be very low. Finnish women also tend to be experienced sauna bathers who know their limits, stay hydrated, and leave when they feel uncomfortable — habits that likely play a significant role in the safety profile.
The 2018 Systematic Review: The Most Balanced Evidence to Date
The single most useful piece of research for expectant mothers trying to make sense of all this was published in 2018 in the British Journal of Sports Medicine by Ravanelli and colleagues at the University of Sydney and the University of Exeter. This systematic review analyzed 12 studies involving 347 pregnant women exposed to various forms of heat stress and produced the most evidence-based safety thresholds currently available.
The key findings were reassuring. No woman in any of the 12 studies exceeded a core body temperature of 39°C — the proposed teratogenic threshold. The highest individual core temperature recorded was 38.9°C, and that was during vigorous land-based exercise, not passive sauna exposure. For sauna use specifically, the average end-of-session core temperature was just 37.6°C — a very modest increase from the typical baseline of 37°C.
Based on their analysis, the researchers concluded that pregnant women can safely sit in a hot/dry sauna at 70°C (158°F) with 15% relative humidity for up to 20 minutes, irrespective of pregnancy stage, without their core temperature exceeding the teratogenic threshold. They also concluded that hot baths at 40°C (104°F) were safe for up to 20 minutes under the same conditions.
This study was notable because it provided specific, evidence-based guidelines rather than the vague "avoid heat" advice that characterizes most official recommendations. It also acknowledged that pregnant women's thermoregulatory capacity may actually be enhanced during pregnancy, not diminished — a finding that contradicts the widespread assumption that pregnant women overheat more easily.
That said, the researchers emphasized that these guidelines apply to controlled conditions with specific temperature limits and session durations. They do not provide a green light for extended sessions, extremely hot saunas, or situations where a woman might not be able to monitor her body's signals effectively.
Sauna Safety by Trimester
First Trimester (Weeks 1–12): Greatest Caution Warranted
The first trimester is the period of greatest vulnerability because this is when the neural tube closes (around weeks 3–4) and all major organ systems begin to form. Virtually all of the research linking hyperthermia to birth defects focuses on this window. Because many women don't even know they're pregnant during the earliest and most critical weeks, this trimester deserves the most conservative approach.
Most healthcare providers recommend avoiding sauna use entirely during the first trimester, and this is the guidance we'd echo. If you used a sauna before you knew you were pregnant, don't panic — the Finnish data and the 2018 systematic review both suggest that typical sauna sessions are unlikely to raise core temperature to dangerous levels. But once you know you're expecting, it's wise to press pause until you've cleared the first 12 weeks and discussed your plans with your doctor.
Second Trimester (Weeks 13–26): Lower Risk, Still Cautious
By the second trimester, the critical window for neural tube formation has passed. The major organs and structures are in place and are now growing and maturing rather than forming from scratch. This significantly reduces — though does not eliminate — the risk associated with heat exposure.
If your pregnancy is progressing normally and your healthcare provider gives the green light, very brief, moderate sauna sessions may be an option during the second trimester. "Brief and moderate" means keeping air temperature at or below 70°C (158°F), limiting sessions to 10–15 minutes, staying well-hydrated before and during your session, and exiting immediately at the first sign of dizziness, nausea, or discomfort.
Third Trimester (Weeks 27–40): Additional Considerations
In the third trimester, the birth defect risk from heat is very low, but new concerns emerge. Your cardiovascular system is already working overtime — blood volume has increased by up to 50%, your heart rate is elevated, and your body is carrying significantly more weight. Adding sauna heat on top of this workload can amplify feelings of dizziness and fatigue, and can cause blood pressure to drop more rapidly than it would in a non-pregnant state.
There is also some evidence, primarily from historical observations, that prolonged heat exposure late in pregnancy can trigger premature contractions. While a short, moderate sauna session is unlikely to induce labor, it's another reason to keep sessions brief and to listen closely to your body.
If you do use a sauna in the third trimester, consider keeping sessions under 10 minutes, having someone nearby, keeping cool water within arm's reach, and rising slowly when you're done to avoid orthostatic hypotension (a sudden drop in blood pressure upon standing).
Traditional Sauna vs. Infrared Sauna vs. Steam Room: Does the Type Matter?
Not all heat environments are created equal, and the type of sauna you use does affect the risk profile during pregnancy.
Traditional (Finnish) Sauna
A traditional sauna uses an electric or wood-burning heater loaded with stones to heat the air in the room, typically to temperatures between 150°F and 195°F (65°C–90°C). The vast majority of pregnancy-related sauna research — including the reassuring Finnish studies and the 2018 Ravanelli systematic review — was conducted on traditional saunas. When the research says "pregnant women can safely sit in a sauna at 70°C for 20 minutes," it's referring to this type of sauna.
Because the room air is extremely hot but your body's cooling mechanisms (primarily sweating) work effectively in the dry heat, traditional saunas tend to raise core temperature more slowly than water-based heat sources like hot tubs. This is actually a safety advantage — it gives you more time to notice when you're getting warm and to exit before reaching a problematic threshold.
Infrared Sauna
Infrared saunas operate at significantly lower air temperatures than traditional saunas — typically 120°F to 150°F (49°C–65°C) — but use infrared light to heat your body directly rather than heating the surrounding air. This means you feel warm and sweat profusely even though the ambient temperature is much lower.
Here's the important nuance: nearly all the pregnancy-safety research has been conducted on traditional saunas, not infrared saunas. Because infrared energy heats the body through a fundamentally different mechanism — penetrating tissue directly rather than warming it through convection — the safety data from traditional sauna studies cannot be automatically applied to infrared saunas.
Some practitioners argue that infrared saunas are safer during pregnancy because the ambient temperature is lower. Others point out that because infrared radiation heats the body more directly and efficiently, it may actually raise core temperature faster despite the lower room temperature. The honest answer is that we don't have enough pregnancy-specific research on infrared saunas to make a confident safety determination. Until that research exists, most experts recommend treating infrared saunas with the same caution as traditional saunas during pregnancy.
Steam Room
Steam rooms operate at lower temperatures than traditional saunas (typically 110°F–120°F / 43°C–49°C) but at near-100% humidity. The high humidity impairs your body's primary cooling mechanism — sweating — because sweat cannot evaporate efficiently in saturated air. This means your core temperature can rise faster in a steam room than in a dry sauna at the same air temperature.
For this reason, steam rooms may actually carry a higher risk of overheating during pregnancy than a traditional dry sauna at a moderate temperature. If you're going to use any type of heat therapy during pregnancy, a traditional dry sauna at a controlled, moderate temperature is likely the safest option based on available evidence.
Key Risks of Sauna Use During Pregnancy
Even outside the context of birth defects, sauna use during pregnancy carries several practical risks that are worth understanding:
Dehydration. Pregnancy already increases your body's fluid requirements substantially. A sauna session can cause you to lose a significant amount of fluid through sweat in a short period. Dehydration during pregnancy can reduce amniotic fluid levels, contribute to Braxton Hicks contractions, and in severe cases, compromise blood flow to the placenta.
Low blood pressure and fainting. Pregnancy causes blood vessels to dilate and blood volume to shift toward the uterus and placenta. Sauna heat amplifies this vasodilation, which can cause a sudden drop in blood pressure. Feeling lightheaded is common; fainting is a real possibility — and a fall during pregnancy poses its own serious risks to both mother and baby.
Overheating without awareness. Pregnancy alters your baseline body temperature and your perception of heat. You may not recognize the warning signs of overheating — flushing, rapid heartbeat, nausea — as quickly as you normally would, especially if you're accustomed to regular sauna use and have developed a higher heat tolerance.
Premature contractions. While the evidence is primarily anecdotal, heat stress combined with dehydration has been associated with uterine irritability and premature contractions, particularly in the third trimester. This doesn't mean a 10-minute sauna session will send you into labor, but it's a reason to be cautious and to hydrate aggressively.
If You Choose to Use a Sauna While Pregnant: Safety Guidelines
If your healthcare provider has cleared you for limited sauna use — typically in the second or third trimester of an uncomplicated pregnancy — here are evidence-informed guidelines to minimize risk:
Keep sessions short. Limit your time to 15 minutes or less. The 2018 Ravanelli review found that 20 minutes at 70°C (158°F) kept core temperature well below the danger threshold, but building in a safety margin is wise.
Lower the temperature. If you have a home sauna and can control the temperature, set it to 150°F (65°C) or below rather than running it at full capacity. This gives you a more comfortable margin without sacrificing the relaxation benefit.
Hydrate before, during, and after. Drink at least 16 ounces of water before entering the sauna, bring water in with you, and continue hydrating after your session. Electrolyte drinks are also helpful, especially in later pregnancy.
Listen to your body ruthlessly. If you feel dizzy, lightheaded, nauseous, unusually flushed, or simply "off," exit immediately. Do not push through discomfort the way you might when you're not pregnant.
Avoid the hottest spots. In a traditional sauna, heat rises. Sitting on a lower bench keeps you in cooler air. Avoid lying flat on an upper bench where temperatures can be significantly higher.
Bring a buddy. Never sauna alone while pregnant. Having someone nearby — whether in the sauna or just outside — ensures that help is available if you feel faint.
Cool down gradually. Skip the cold plunge or cold shower immediately after your sauna session. Rapid temperature changes can cause a sudden spike in blood pressure. Instead, allow your body to cool down naturally at room temperature.
Monitor your temperature if possible. A sauna thermometer lets you confirm the room temperature, and an oral or ear thermometer can help you track your own body temperature if you want an extra layer of reassurance.
High-Risk Situations: When Saunas Are Off the Table
Regardless of trimester or sauna type, certain conditions make sauna use during pregnancy inadvisable under any circumstances. These include preeclampsia or pregnancy-induced hypertension, a history of preterm labor or premature rupture of membranes, placenta previa or other placental abnormalities, gestational diabetes (particularly if poorly controlled), carrying multiples, any condition requiring bed rest or activity restriction, and a history of fainting or severe dizziness during the current pregnancy.
If any of these apply to you, sauna use should be completely avoided until after delivery and your postpartum recovery is well underway. Your healthcare provider is the only appropriate person to make this call.
What If You Used a Sauna Before You Knew You Were Pregnant?
This is one of the most common — and most anxiety-inducing — questions expectant mothers ask. If you had a regular sauna session (or even several) in the very early weeks before you realized you were pregnant, the evidence strongly suggests there is no reason to panic.
The Finnish population data is the most reassuring reference point here: with 90%+ of pregnant women continuing to use the sauna throughout pregnancy and no elevated rates of NTDs or other birth defects, it's clear that occasional or even regular sauna exposure at typical temperatures is very unlikely to cause harm. The 2018 systematic review reinforces this by showing that core temperatures during typical sauna sessions remain well below the teratogenic threshold.
If you're concerned, mention it to your OB-GYN or midwife. They can review your specific situation and, if needed, order a prenatal ultrasound or alpha-fetoprotein blood test to screen for neural tube defects. But the overwhelming likelihood is that everything is perfectly fine.
Safe Alternatives for Relaxation During Pregnancy
If you're sidelining your sauna sessions for the duration of your pregnancy — or if your healthcare provider has asked you to — there are plenty of effective alternatives for stress relief and muscle comfort:
Warm (not hot) baths. A bath at or below 100°F (38°C) is generally considered safe during pregnancy. This is warm enough to be soothing and relieve muscle tension without raising your core temperature to a concerning level. Use a bath thermometer to verify the temperature.
Prenatal massage. Licensed prenatal massage therapists are trained to work safely with pregnant women and can address common discomforts like lower back pain, hip pain, swollen legs, and overall tension.
Gentle stretching and prenatal yoga. Both help with muscle tightness, circulation, and stress — many of the same benefits people seek from a sauna session. Prenatal yoga classes also provide community and emotional support.
Warm compresses. A heating pad or warm towel applied locally to sore muscles (lower back, hips, shoulders) provides targeted relief without raising your overall body temperature.
Meditation and breathing exercises. The mental relaxation component of a sauna session — the quiet, the disconnect, the decompression — can be replicated through guided meditation, progressive muscle relaxation, or simple deep-breathing practices.
Sauna Use After Pregnancy and While Breastfeeding
The good news: once you've delivered and your body has had time to recover, sauna use is generally considered safe — including while breastfeeding. There's no evidence that sauna-induced sweating affects breast milk composition or supply in any clinically meaningful way.
That said, give your body adequate time to recover postpartum before jumping back into the heat. Most practitioners recommend waiting at least 6 weeks after a vaginal delivery and longer after a C-section. Start with shorter, lower-temperature sessions and work your way back up gradually. Stay hydrated — breastfeeding already increases your fluid needs, and adding sauna-induced sweating on top of that means you'll need to drink even more water than usual.
If you've been dreaming about getting back to your home sauna routine throughout your pregnancy, postpartum is your well-earned return. Many new parents find that a 20-minute evening sauna session becomes one of the most valuable parts of their self-care routine during the demanding newborn period — a brief but powerful reset for both body and mind.
Sauna Use and Fertility: What to Know If You're Trying to Conceive
If you're not yet pregnant but are actively trying to conceive, sauna use is worth a brief mention. For women, the evidence does not suggest that regular sauna bathing impairs fertility. However, if you're undergoing IVF or other assisted reproductive procedures, most fertility specialists recommend avoiding saunas during ovarian stimulation, after embryo transfers, and during the two-week wait, since some animal studies suggest extreme heat can impact implantation.
For male partners, the data is more clear-cut: regular sauna use (and other forms of scrotal heat exposure) can temporarily reduce sperm count and motility. The effect is reversible — sperm parameters typically return to normal within a few months of stopping — but it's worth being aware of if you're having difficulty conceiving. A temporary break from the sauna may be a simple and no-cost intervention while actively trying.
The Bottom Line
Sauna use during pregnancy is not the clear-cut danger that many sources portray, but it's also not something to approach casually. The best available evidence suggests that short, moderate traditional sauna sessions (around 70°C / 158°F for 15–20 minutes) are unlikely to raise a healthy pregnant woman's core temperature to a level that poses a risk to her baby — but this comes with important caveats about trimester, individual health status, and the type of sauna being used.
The safest approach — and the one endorsed by most major medical organizations — is to avoid saunas during the first trimester entirely and to use them only sparingly, at lower temperatures and for shorter durations, during the second and third trimesters if your healthcare provider approves. If you have any high-risk pregnancy conditions, saunas should be off the table until after delivery.
Above all, this is a decision to make with your doctor or midwife, not with the internet. Every pregnancy is different, and what's safe for one woman may not be appropriate for another. Bring the research, ask the questions, and make the choice that feels right for your body and your baby.
Haven Of Heat and its associates do not provide medical guidance. All of the information contained in this article is for general informational and educational purposes only and should not be relied upon as a substitute for advice from your healthcare provider. Consult a licensed physician or midwife before making decisions about sauna use during pregnancy.
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