Are hot tubs and saunas safe during pregnancy?

The hyperthermia concern

Maternal hyperthermia — specifically, core body temperature rising above 102.2°F (39°C) for more than 10 minutes — has been associated with an increased risk of neural tube defects (spina bifida, anencephaly) in offspring when exposure occurs during the first trimester, particularly weeks 4–7 of gestation1.

This is the same biological concern that makes high fevers during early pregnancy a medical priority. Heat itself, regardless of source, is the issue.

Specific guidance

Hot tubs and Jacuzzis

Avoid throughout pregnancy. Most residential hot tubs are set to 102–104°F — right at or above the threshold of concern. Standing in 102°F water for 10+ minutes will raise core temperature into the risk zone2. ACOG explicitly cautions against hot tubs in pregnancy.

Saunas (dry)

Avoid in the first trimester. Use briefly (5–10 minutes max), with lower temperatures (under 158°F / 70°C), in second/third trimesters only with OB approval and adequate hydration. Get out at the first sign of dizziness or overheating.

Steam rooms

Same guidance as saunas, but steam rooms heat the body faster due to humidity blocking evaporative cooling. Be more conservative.

Warm baths

Fine in pregnancy. Standard warm-bath temperature (95–100°F / 35–38°C) doesn’t raise core body temperature meaningfully. A relaxing 20-minute soak at comfortable temperature is safe. The rule of thumb: if you can’t comfortably stay in for 20+ minutes, it’s too hot.

Hot yoga and Bikram

Avoid in pregnancy. Room temperatures of 95–105°F combined with intense physical activity can rapidly raise core temperature. Most yoga studios will refuse pregnant attendees in hot yoga classes.

Swimming pools

Generally fine. Standard pool temperatures (78–84°F) cool the body rather than warming it. Active swimming is one of the recommended pregnancy exercises3.

Warning signs of overheating

• Dizziness or lightheadedness
• Nausea
• Excessive sweating
• Increased heart rate
• Confusion or difficulty concentrating
• Skin flushing

If you experience any of these, exit the heat source immediately, hydrate, and cool down. Contact your OB if symptoms persist.

A note on infrared saunas

Infrared saunas typically operate at lower temperatures (110–140°F) than traditional saunas. Some practitioners promote them as pregnancy-safe, but the mechanism (heating from within) actually raises core temperature MORE effectively than traditional dry saunas at equivalent ambient temperatures. The pregnancy precaution still applies.