USE OF SAUNAS AND STEAMROOMS IN PREGNANCY

The hypothesis that gestational exposure to external heat sources such as saunas, steam rooms, hot tubs and hot baths might cause birth defects is based on the results of animal studies which showed that a rise in the core body temperature of 2.5°C or more was associated with teratogenicity. Some human studies have suggested that maternal fever in the first trimester of pregnancy might increase the likelihood of neural tube defects (NTDs), but findings are inconsistent. It is also unclear whether a rise in body temperature due to febrile illness equates to a rise in body temperature caused by exposure to an external heat source. As a precautionary measure the Royal College of Obstetricians and Gynaecologists (RCOG) suggest that where hydrotherapy pools are used during pregnancy, the temperature should not exceed 35°C.

There are limited data on most pregnancy outcomes following maternal exposure to external heat sources such as saunas, hot tubs and hot baths. There are no data relating specifically to steam room exposure. Three out of the four case-control studies that have been carried out have reported that gestational exposure to hot tubs and hot baths might be associated with an increased risk of NTDs in the offspring. Conclusions regarding risk are, however, limited by the nature of the data and lack of information about the degree of maternal core temperature increase and duration of exposure. The limited available evidence does not currently signal that use of saunas increases the risk of NTDs, but is insufficient to state that no increase in risk exists. Data on other specific congenital malformations are too limited to permit an evidence-based assessment of risk.

One cohort study suggested that women who had used a hot tub or whirlpool bath after conception were approximately twice as likely to experience a spontaneous abortion than those without a history of such use, however, as this is a single study further research is required to confirm this finding. There are no studies which investigate rates of other pregnancy outcomes following gestational exposure to external heat sources. An evidence-based assessment of the potential risks of stillbirth, intrauterine growth restriction (IUGR), preterm delivery and adverse neurodevelopmental effects following in utero exposure is therefore not possible, and women wishing to partake in such exposures should be aware of the lack of evidence.

Exposure to external heat sources such as saunas, steam rooms, hot tubs or hot baths at any stage in pregnancy would not usually be regarded as medical grounds for termination of pregnancy or any additional fetal monitoring. However, other risk factors may be present in individual cases which may independently increase the risk of adverse pregnancy outcome. Clinicians are reminded of the importance of consideration of such factors when performing case-specific risk assessments.
                      
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