Sauna During Pregnancy: Is It Safe?
Updated January 2025 — Backyard Sauna Pro
The short version: most medical guidelines advise against sauna use during pregnancy, particularly in the first trimester. The concern is not the sauna itself — it is hyperthermia. Here is why, what the evidence shows, and what the official guidance says.
The Hyperthermia Risk
A traditional sauna runs 160-185°F. At these temperatures, core body temperature rises — typically reaching 100-102°F within 10-15 minutes for most people. This is the threshold where fetal risk becomes a concern.
Multiple studies have found that sustained core temperatures above 102°F (39°C) during the first trimester are associated with increased risk of neural tube defects. The developing nervous system is particularly sensitive to heat in weeks 3-8 of pregnancy. Later in pregnancy, overheating increases dehydration risk and can cause blood pressure changes that reduce placental blood flow.
What Medical Organizations Say
The American College of Obstetricians and Gynecologists (ACOG) advises pregnant women to avoid activities that raise core body temperature above 102°F, including hot tubs, saunas, and steam rooms — especially in the first trimester.
Nordic countries, where sauna culture is deeply embedded, have studied this question extensively. Finnish guidelines allow brief, lower-temperature sauna use in later pregnancy for women who have an established sauna habit and no complications — but they are explicit that this is at the discretion of the treating physician and not a general recommendation.
Infrared Saunas During Pregnancy
Infrared saunas run at lower air temperatures (120-140°F) than traditional saunas. Some people assume this makes them safer in pregnancy. This reasoning is incomplete — infrared radiation penetrates tissue more deeply than convected air heat, and the core body temperature rise can be similar or greater. Most maternal-fetal medicine guidelines make no distinction between infrared and traditional saunas. The same avoidance recommendation applies, especially in the first trimester.
When It May Be Acceptable
Some physicians in Scandinavian countries permit brief (5-10 minute) moderate-temperature sauna use in the second and third trimesters for patients with no complications who have been regular sauna users before pregnancy. The logic is that habituated users are more efficient at thermoregulation and are less likely to reach dangerous core temperatures in a short session.
This is not a general recommendation, and it requires explicit sign-off from a physician who knows the patient's specific situation. First trimester is not included in any of these exceptions.
The Practical Bottom Line
- First trimester: Avoid entirely. Neural tube development is most vulnerable during weeks 3-8.
- Second and third trimesters: Still not recommended without explicit physician approval. Individual risk factors vary significantly.
- Infrared sauna: Same restrictions apply — do not assume lower air temperature means lower risk.
- After delivery: Most women can return to normal sauna use once cleared by their doctor, typically 4-6 weeks postpartum.
FAQ
Is sauna safe during pregnancy?
Most guidelines advise against it, especially in the first trimester. Core temperature above 102°F is associated with fetal risks. Consult your OB or midwife.
Can you use an infrared sauna while pregnant?
Same restrictions as traditional sauna apply. Lower air temperature does not mean lower core temperature rise.
What are the risks of sauna during pregnancy?
Hyperthermia is the primary concern, linked to neural tube defects in the first trimester. Later risks include dehydration, blood pressure changes, and reduced fetal blood flow.