Are hot tubs safe during pregnancy?

What does the evidence say about hot tubs during pregnancy?

1. Raising your core body temperature above about 102°F during the first trimester has been linked to a higher chance of neural tube defects. 1
2. Most public hot tubs sit at around 104°F, hot enough to push your core temperature above that 102°F mark in just 10 to 20 minutes. 1
3. Pregnant people are more vulnerable to heat-related illness in general, which is why it's smart to avoid anything that substantially raises your core temperature. 2
4. A brief warm bath under 100°F is a safer alternative: it doesn't raise your core temperature anywhere near the concerning threshold. 1

Is hot tubs safe in each trimester?

• First trimester. This is the highest-stakes window, since neural tube closure happens around weeks 3 to 4. Studies link a core temperature above 102°F to a higher chance of neural tube defects.
• Second trimester. The same core-temperature caution continues. Lightheadedness and fainting also become more likely now as your circulation changes.
• Third trimester. Same guidance as earlier. A shorter warm bath under 100°F is generally the better choice over a hot tub.