GUIDE
Avoid hot tubs during pregnancy, especially in the first trimester. The heat can raise your core body temperature to unsafe levels.
ACOG recommends that pregnant people avoid hot tubs and saunas because core body temperatures above 102.2°F (39°C) are associated with an increased risk of neural tube defects in the first trimester and may cause dehydration and dizziness later in pregnancy. Warm baths (under 100°F) are a safe alternative.
Be prepared from day one
During the first trimester, the baby's neural tube — which develops into the brain and spinal cord — is forming. Research shows that sustained core body temperatures above 102.2°F (39°C) during this critical period are associated with an increased risk of neural tube defects such as spina bifida and anencephaly. This is the same reason high fevers in early pregnancy warrant treatment.
Hot tubs are typically set between 100-104°F and maintain that temperature continuously, unlike a bath where the water cools. In a hot tub, your core body temperature can rise to unsafe levels within 10-20 minutes. Your body's normal cooling mechanism (sweating) is less effective when you are immersed in hot water.
After the first trimester, the neural tube is fully formed, but overheating still poses risks: dehydration, dizziness, and drops in blood pressure that can reduce blood flow to the placenta. This is why ACOG recommends avoiding hot tubs throughout pregnancy, not just in the first trimester.
A warm bath is the best alternative. Keep it comfortable but not hot, and limit your time.
The common thread is sustained exposure to temperatures above 100°F. Brief exposure is less risky than prolonged immersion.
If you do not have a thermometer, test the water with your elbow or inner wrist — it should feel warm and comfortable, not hot. If it makes your skin turn red or if you start to sweat, it is too hot. Your upper chest, arms, and head should stay above the water to help your body regulate temperature.
If you choose to use a hot tub during pregnancy (after the first trimester), minimize the risk by keeping the temperature at 100°F or below, limiting your time to 10 minutes maximum, sitting with your arms and upper chest above the water, getting out immediately if you feel dizzy, lightheaded, or overheated, and staying well hydrated.
However, the safest approach is to skip the hot tub entirely during pregnancy and enjoy warm baths instead. The temperature difference between a warm bath and a hot tub is significant in terms of risk.
The same overheating principle applies to exercise during pregnancy. Hot yoga and hot Pilates should be avoided because they are conducted in rooms heated to 95-105°F, which can raise your core temperature above safe levels. Regular yoga and Pilates at room temperature are excellent options — see our prenatal yoga guide.
Swimming is one of the safest and most comfortable exercises during pregnancy because the water keeps your body cool while you exercise. For more safe activities, see our pregnancy exercise guide. If you are looking for ways to stay comfortable in the heat, our sleep positions guide covers how to rest more comfortably at night. And for overall prenatal care questions, see our prenatal visit schedule.
This guide is for informational purposes only and is not a substitute for professional medical advice. Always consult your healthcare provider with any questions about your pregnancy.
