Pregnancy brings countless decisions about health and wellness—and one question that often arises is whether heat therapies like saunas and hot tubs are safe during early pregnancy. The American College of Obstetricians and Gynecologists (ACOG) has issued clear guidance on this topic, and for expectant mothers considering infrared sauna use, understanding the rationale is essential.
This article explains ACOG's recommendations on heat exposure during pregnancy, why overheating poses specific risks in the first trimester, and what the science tells us about infrared saunas in particular. Whether you're a current sauna user wondering about pregnancy, or a healthcare provider seeking evidence-based guidance, this resource provides the information you need to make informed decisions.
Why ACOG Recommends Avoiding Excessive Heat During Early Pregnancy
ACOG's position on sauna and hot tub use during pregnancy centers on a single critical concern: maternal core temperature elevation.
During the first trimester—particularly the first 8–12 weeks—the developing embryo and fetus are uniquely vulnerable to heat stress. Unlike adults, who can regulate their internal temperature through sweating and vasodilation, the fetus cannot. If maternal core temperature rises significantly, fetal temperature follows passively, and the fetus lacks mechanisms to cool itself.
Research from animal models and epidemiological studies has suggested that maternal hyperthermia (elevated core body temperature) during early pregnancy, particularly in the first trimester, may be associated with an increased risk of neural tube defects and other congenital anomalies. While human studies are limited and observational, this evidence has led ACOG and other medical organizations to recommend avoiding prolonged heat exposure that raises core body temperature above 38.9°C (102°F) during the first trimester.
ACOG specifically advises against:
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Immersion in hot tubs or hot baths where water temperature exceeds 104°F (40°C)
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Prolonged sauna use, especially in the first trimester
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Any activity designed to raise core body temperature significantly
The key word here is prolonged. Brief exposures to warm environments are generally considered lower-risk than sustained heat stress, but ACOG errs on the side of caution during early pregnancy.
Infrared Saunas and Core Temperature: What the Research Shows
Infrared saunas differ from traditional Finnish dry saunas in how they deliver heat. Rather than heating the air around you, infrared saunas emit infrared radiation that penetrates skin and tissue, raising core body temperature through direct thermal energy transfer.
A 2022 study examining infrared sauna use in healthy women found that tympanic (ear canal) temperature rose more during infrared sauna exposure than during exercise or control conditions. Specifically, mean tympanic temperature increased by 1.05°C during infrared sauna use—a clinically meaningful elevation (Hussain et al., 2022). This demonstrates that infrared saunas are indeed effective at raising core temperature, which is the very mechanism ACOG cautions against during pregnancy.
In another infrared sauna trial involving 12 adults with type 2 diabetes, a single 40-minute session at 60°C raised core temperature to approximately 38.0°C (Schenaarts et al., 2024). While this temperature is below the 38.9°C threshold ACOG identifies as concerning, it was achieved in a controlled clinical setting with healthy or relatively stable participants—not in a pregnant individual, where vulnerability is greater.
The implication is clear: infrared saunas reliably elevate core temperature, and during early pregnancy, this elevation should be avoided.
The Distinction: Traditional Sauna Evidence vs. Infrared Sauna Evidence
An important caveat deserves mention: most of the large sauna health studies that have documented cardiovascular, neurological, and longevity benefits come from traditional Finnish dry sauna research, not infrared sauna research. infrared sauna cardiovascular health guide
The famous Finnish KIHD cohort studies, which found that 4–7 sauna sessions per week were associated with reduced cardiovascular mortality (Laukkanen et al., 2015), lower hypertension incidence (Zaccardi et al., 2017), and reduced dementia risk (Laukkanen et al., 2017), all examined traditional dry sauna bathing—not infrared saunas. These studies generally included men in midlife or older, followed over 15–25 years, and do not directly address infrared sauna use or pregnancy.
The infrared sauna research base is smaller and more recent. While some studies suggest infrared sauna may offer benefits in heart failure (Kihara et al., 2002; Kihara et al., 2009), pain management (Oosterveld et al., 2009), and recovery from exercise (Ahokas et al., 2023), most are small pilot studies, often conducted in Japan using the Waon thermal therapy protocol (a standardized 60°C far-infrared sauna). None of these studies included pregnant participants, and none were designed to assess fetal safety.
This distinction matters: the infrared sauna evidence base does not provide reassurance about safety in pregnancy, because no research has prospectively examined infrared sauna use during pregnancy.
ACOG's Broader Heat Guidance: A Pregnancy-Centered Framework
ACOG's caution about heat exposure extends beyond saunas. The organization also recommends:
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Avoiding prolonged hot baths and hot tubs (water above 104°F) during pregnancy
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Being cautious with vigorous exercise during early pregnancy, particularly in hot environments, where core temperature may rise
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Staying hydrated and taking breaks if spending time in warm settings
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Monitoring for dizziness, nausea, or overheating, which may indicate excessive thermal stress
The logic underlying these recommendations is preventive: because we cannot ethically conduct randomized trials of hyperthermia in pregnant women, guidance is based on animal research, case reports, and observational data. ACOG adopts a conservative approach to protect fetal development during the vulnerable first trimester.
Alternatives to Sauna During Early Pregnancy
If you are pregnant and have been a regular sauna user, this guidance doesn't mean forgoing all heat-based wellness practices. Several lower-risk alternatives exist:
Warm (not hot) baths and showers Warm water immersion below 104°F is generally considered safe and can provide muscle relaxation and stress relief without excessive core temperature elevation. infrared sauna for muscle recovery
Gentle yoga and stretching Prenatal yoga classes, offered in a room-temperature or slightly warm environment, offer flexibility and relaxation benefits without the risk of uncontrolled heat exposure.
Prenatal massage Therapeutic massage, performed by a provider experienced with pregnancy, can address muscle tension and promote relaxation safely.
Warm compress therapy Localized heat applied to sore muscles (e.g., lower back, neck) via a warm compress is much less likely to raise core body temperature significantly.
Walking and light aerobic activity Moderate-intensity activities like walking, swimming in cool water, or stationary cycling are safe during pregnancy (with provider clearance) and provide cardiovascular and mental health benefits.
Returning to Sauna Use After Pregnancy
For those who wish to resume sauna use postpartum, the timeline depends on how you delivered:
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Vaginal delivery without complications: Most women can resume normal activities, including sauna use, once any active bleeding has ceased and they feel physically ready—typically 2–4 weeks postpartum, with clearance from their healthcare provider.
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Cesarean delivery: Recovery typically takes longer (6–8 weeks), and sauna use should be postponed until the incision is fully healed and cleared by your obstetrician.
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Breastfeeding: There is no evidence that maternal sauna use poses a risk to breast milk composition or infant safety, though staying well-hydrated during sauna use is important for milk supply.
As with all postpartum activities, check with your obstetrician or midwife before resuming sauna use, particularly if you have any complications or concerns.
Key Takeaways for Healthcare Providers and Patients
If you're advising a pregnant patient (or are pregnant yourself):
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ACOG recommends avoiding prolonged sauna and hot tub use during early pregnancy, particularly the first trimester, to prevent maternal core temperature from exceeding 38.9°C (102°F).
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Infrared saunas effectively elevate core body temperature—a 2022 study showed rises of approximately 1°C in tympanic temperature during use—making them inconsistent with ACOG guidance during pregnancy.
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The evidence supporting sauna benefits comes primarily from traditional Finnish sauna research in non-pregnant populations. No sauna research (traditional or infrared) has examined fetal outcomes, so safety in pregnancy cannot be claimed.
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The vulnerability of first-trimester fetal development justifies a conservative approach. The developing neural tube and other organ systems during weeks 3–8 are particularly sensitive to thermal stress.
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Safer alternatives exist for relaxation and muscle relief during pregnancy, including warm (not hot) baths, prenatal massage, gentle movement, and localized heat therapy.
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Sauna use can typically resume postpartum after healing is complete and with provider clearance, though specific timelines vary by delivery method.
Frequently Asked Questions
Q1: If I used a sauna before I knew I was pregnant, should I be concerned?
A: Brief, incidental sauna exposure early in pregnancy is unlikely to cause harm. The concern is with prolonged or repeated heat exposure that significantly elevates maternal core temperature. If you used a sauna once or twice before recognizing pregnancy symptoms, this is not considered a high-risk situation. However, once pregnancy is confirmed, it's best to avoid sauna use in the first trimester. Discuss any specific concerns with your obstetrician.
Q2: Are hot tubs safer than saunas during pregnancy?
A: No. Both hot tubs and saunas raise core body temperature, and ACOG advises against both during early pregnancy. The mechanism of harm is the same: maternal hyperthermia. The main difference is that hot tub immersion may feel more comfortable because the water supports your body, but the thermal effect on core temperature is similar or greater. Hot water above 104°F should be avoided.
Q3: Can I use a sauna in the second or third trimester if I avoid overheating?
A: This is a question best discussed with your individual obstetrician. While the highest concern is during the first trimester (when neural tube closure and organ development are occurring), ACOG's guidance on avoiding prolonged heat exposure applies throughout pregnancy. Some providers may allow brief, very warm (but not hot) sauna use later in pregnancy if core temperature is carefully monitored, but this is not standard ACOG guidance. Always defer to your prenatal care provider.
Q4: How does infrared sauna compare to traditional sauna for pregnancy safety?
A: From a fetal safety perspective, there is no meaningful difference. Both traditional and infrared saunas raise core body temperature through different mechanisms (air heating vs. infrared radiation), but the end result is the same. Infrared saunas may reach core temperature elevation more efficiently. Neither is recommended during early pregnancy. The lack of infrared sauna research in pregnant populations means we cannot claim it is safer—and the evidence that it raises core temperature suggests the same precautions apply.
Q5: If I was a regular sauna user before pregnancy, do I have any higher risk?
A: Regular sauna use prior to pregnancy does not increase your risk during pregnancy. However, if you continue sauna use during early pregnancy, you'd be exposing your developing fetus to repeated heat stress, which is what ACOG advises against. The prior sauna use itself is not a risk factor; the recommendation is to pause sauna use during early pregnancy and resume after delivery. Your obstetrician can reassure you that prior sauna use poses no harm to your current pregnancy.
The Bottom Line
ACOG's guidance to avoid sauna and hot tub use during early pregnancy is grounded in evidence that maternal hyperthermia may increase fetal risk during the vulnerable first trimester. Infrared saunas, while offering potential wellness benefits in non-pregnant populations, effectively elevate core body temperature—precisely what pregnancy guidance recommends avoiding.
This is not a prohibition on all heat or comfort; rather, it's a precautionary measure during a critical developmental window. Safer alternatives exist, and sauna use can resume after pregnancy with provider clearance.
If you have questions about sauna use and pregnancy, or you're seeking alternatives for relaxation and wellness during this special time, your obstetrician is the best resource. And if you're interested in resuming infrared sauna use after pregnancy, we encourage you to explore the growing body of evidence on infrared sauna benefits—but always with the guidance of your healthcare provider.
Peak Saunas is committed to evidence-based, safe sauna education. This article does not replace medical advice. Always consult your obstetrician or midwife about heat exposure, sauna use, and wellness practices during pregnancy.
For more on infrared sauna science and health, visit our wellness blog.