Risks of hyperthermia associated with hot tub or spa use by pregnant women

Abstract

There are a limited number of human studies linking hot tub or spa use during early pregnancy to increased risks for neural tube defects (NTDs) or spontaneous abortion. However, these data can be considered in the context of human studies that have demonstrated an association between high maternal fever in early pregnancy and NTDs. In addition, there is a large volume of animal literature suggesting that, regardless of the heat source, an elevated core maternal temperature at or above the threshold of 2 degrees C over baseline, as well as timing and duration of exposure, are the critical factors in conferring risk. Therefore, the potential for hot tub or spa use to increase core maternal body temperature to risky levels and thus increase the risk for NTDs is likely. A woman who knows or who may not yet be aware that she is pregnant should be advised of the recommended limits of exposure. She should also be aware of the possible variability in hot tub or spa temperature readings and be able to accurately monitor maximum water temperature in the hot tub or spa so that her body temperature can be maintained below 38.9 degrees C.

Hyperthermia induces upregulation of Connexin43 in the golden hamster neural tube

“…Among these congenital malformations, NTDs have the highest frequency (Edwards, 2006). The effect of hyperthermia on neural development is closely related to the stage of pregnancy and the duration and amplitude of the temperature increase (Chambers, 2006). Clinical investigation showed that the incidence of NTDs would increase greatly if the temperature exceeded 38.98C during early pregnancy and become even higher if the temperature exceeded 408C (Moretti et al, 2005;Chambers, 2006).…”

“…The effect of hyperthermia on neural development is closely related to the stage of pregnancy and the duration and amplitude of the temperature increase (Chambers, 2006). Clinical investigation showed that the incidence of NTDs would increase greatly if the temperature exceeded 38.98C during early pregnancy and become even higher if the temperature exceeded 408C (Moretti et al, 2005;Chambers, 2006). In this study, we adopted the model of hyperthermia as established in a previous study, in which hyperthermia could induce the NTDs with a rate up to 80% (Feng, et al, 1996).…”

Pregnant women maintain body temperatures within safe limits during moderate-intensity aqua-aerobic classes conducted in pools heated up to 33 degrees Celsius: an observational study

“…If the tympanic temperature was found to be > 1.5 8C above the resting temperature (the safe upper limit for maternal core temperature rise reported in the pregnancy literature [13][14][15] ), or if the participant looked flushed or felt uncomfortably warm or hot, she was asked to cease exercising.…”

Association of Maternal Diseases During Pregnancy with Higher Risk of Congenital Abnormalities (CAs) in Their Children

“…Among human studies the teratogenic effect of hot tub and sauna bathing related hyperthermia (Chambers, 2006) are not shown here, only the possible association of high fever related maternal diseases with CAs mentioned in Table 19.1 is discussed here, although the teratogenic effect of hyperthermia was proved to have a role in the origin of other CAs as well such as microphthalmia (Fraser and Skelton, 1978), facial defects like micrognathia, midfacial hypoplasia, external ear CA, micropenis (due to LH deficiency), and neurogenic contractures Jones, 2004). However, we know a limited number of human studies which were unable to find an association between hyperthermia and CAs (Kleinbrecht et al, 1979;Chambers et al, 1998).…”