Saunas are often sought out for their relaxing warmth and perceived health benefits, making the prospect of using one tempting during pregnancy. A traditional sauna utilizes dry heat, typically ranging from 150°F to 195°F. While this environment is generally safe for non-pregnant individuals, medical consensus advises significant caution and strict time limitations for those who are pregnant. The primary concern revolves around the body’s inability to regulate its temperature effectively when exposed to extreme heat.
The Physiological Risks of Core Body Temperature Elevation
The main danger posed by sauna use during pregnancy is the risk of maternal hyperthermia, which is an abnormally high core body temperature. Medical professionals are concerned when a person’s core temperature exceeds 101°F (38.3°C). Maintaining an elevated temperature above this threshold for an extended period can pose a risk to the developing fetus.
This risk is particularly concentrated during the first trimester, when the fetus’s organ systems are rapidly forming. Studies have shown that maternal hyperthermia in early pregnancy is associated with an increased risk of neural tube defects (NTDs). NTDs are birth defects that affect the brain and spinal cord, such as spina bifida and anencephaly. The neural tube closes very early, typically by the sixth week of pregnancy, making this window the most susceptible to heat-related harm.
The body attempts to cool itself in the heat by diverting blood flow to the skin’s surface, enabling sweating. For a pregnant person, this peripheral vasodilation can cause a drop in blood pressure and a resulting increase in heart rate. This response is meant to protect the mother from overheating, but it can also divert blood away from the uterus, potentially compromising fetal blood supply. Furthermore, the intense sweating can quickly lead to dehydration, which can trigger complications.
Research suggests that exposure to maternal hyperthermia in early pregnancy may nearly double the odds of a neural tube defect. The underlying mechanism involves the heat disrupting protein stability necessary for the proper closure of the neural tube. Pregnant individuals must avoid any environment that could raise their core temperature above the suggested safety limit, whether through fever or external heat sources.
Medical Recommendations and Time Limits
The general medical guidance for sauna use during pregnancy is rooted in minimizing the risk of core temperature elevation. Leading medical organizations suggest that a pregnant person should not allow their core body temperature to rise above 102.2°F (39°C). To prevent reaching this threshold, strict limits on both temperature and duration must be observed.
It is advised to avoid saunas where the temperature exceeds 150°F. If a pregnant person chooses to use a sauna after the first trimester, the session should be limited to a maximum of 15 minutes. For most, a duration of 10 minutes or less is a safer, more conservative approach to heat exposure.
The highest risk occurs in the first trimester, which is why most healthcare providers advise complete abstinence from saunas during this time. Use in the second and third trimesters carries a lower risk for congenital anomalies, but the possibility of dehydration and fainting remains. Any use during later pregnancy should be discussed with a healthcare provider and requires continuous monitoring.
Hydration is a non-negotiable part of any heat exposure during pregnancy. It is important to drink water before and immediately after entering a sauna environment to mitigate fluid loss from sweating. A pregnant person should exit the sauna immediately if they feel dizzy, faint, or experience a rapid pulse, as these are clear signs of overheating.
Differentiating Heat Environments and Their Risks
The risks associated with a traditional dry sauna do not exist in isolation, as other heat environments pose similar or greater threats. Hot tubs, for instance, are considered an equal or greater risk than saunas. The water is typically set between 100°F and 104°F, and full immersion prevents the body from utilizing evaporative cooling through sweating.
Because of this immersion, it takes less time—often as little as 10 to 20 minutes—for the core temperature to rise to a concerning level. For this reason, the recommended maximum duration for hot tub use during pregnancy is even shorter than a sauna, typically no more than 10 minutes. Sitting with the upper body and arms out of the water can help mitigate heat transfer.
Steam rooms, while operating at a lower temperature than saunas (around 110°F to 120°F), also present a core temperature risk. The high humidity in a steam room saturates the air, severely limiting the body’s ability to cool itself through the evaporation of sweat. This lack of evaporative cooling means that the core temperature can still rise to unsafe levels, requiring the same cautious time limits as saunas.
Infrared saunas use radiant heat to warm the body directly rather than heating the surrounding air to the same high temperatures as a traditional sauna. While some suggest this method is safer, the fundamental risk remains that the direct heat can elevate the maternal core temperature. Therefore, the same stringent time limits and temperature monitoring should be applied to infrared sauna sessions.