7/6/07njm

**Q. Should patients use sweat lodges during pregnancy?**

A. A sweat lodge that does not elevate the maternal core temperature
would be acceptable.

Hyperthermia has been associated with a manifold increase in neural tube
defects.

On the other hand, a sweat lodge experience that does not elevate the
maternal core temperature would be acceptable.

**Background**

In animal studies, an increase in maternal core temperature of greater
than 1.5 degree C during embryogenesis has been observed to cause major
congenital malformations (eg, neural tube defects, microphthalmia,
arthrogryposis, abdominal wall defects, limb deficiencies). These data
coupled with human studies suggest that maternal hyperthermia (related
to exposure to a hot tub, sauna, or fever) in excess of 39 degrees
during the first 45 to 60 days of gestation may also be teratogenic in
humans. Hyperthermia associated with exercise, however, has not been
associated with teratogenic consequences in humans.

Data regarding the effects of exercise on core temperature during
pregnancy are limited. Fetal temperatures are approximately 1 degree C
higher than maternal temperatures (fetal temperature is 0.5 degrees
higher than intrauterine temperature which is 0.8 degrees higher than
maternal oral temperature).

**Resources**

[Chambers
CD](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Search&itool=pubmed_Abstract&term="Chambers+CD"%5BAuthor%5D)
et al Maternal fever and birth outcome: a prospective study.
[Teratology.](javascript:AL_get(this, 'jour', 'Teratology.');) 1998
Dec;58(6):251-7.\
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstract&list_uids=9894674>

Martinez-Frias ML et al High maternal fever during gestation and severe
congenital limb disruptions. Am J Med Genet 2001 Jan 15;98(2):201-3.

<http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=11223858>

[Moretti
ME](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Search&itool=pubmed_Abstract&term="Moretti+ME"%5BAuthor%5D),
et al Maternal hyperthermia and the risk for neural tube defects in
offspring: systematic review and meta-analysis.

[Epidemiology.](javascript:AL_get(this, 'jour', 'Epidemiology.');) 2005
Mar;16(2):216-9

<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstract&list_uids=15703536>

Milunsky A et al Maternal heat exposure and neural tube defects.
[JAMA.](javascript:AL_get(this, 'jour', 'JAMA.');) 1992 Aug
19;268(7):882-5

<http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=1640616>

[Padmanabhan
R](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Search&itool=pubmed_Abstract&term="Padmanabhan+R"%5BAuthor%5D).
et al Etiology, pathogenesis and prevention of neural tube defects.
[Congenit Anom
(Kyoto).](javascript:AL_get(this, 'jour', 'Congenit Anom (Kyoto).');)
2006 Jun;46(2):55-67.\
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstract&list_uids=16732763>

Sasaki J et al Exercise at high temperature causes maternal hyperthermia
and fetal anomalies in rats. Teratology. 1995 Apr;51(4):233-6.

<http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=7570364>

[Suarez
L](http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Search&itool=pubmed_Abstract&term="Suarez+L"%5BAuthor%5D),
et al The effect of fever, febrile illnesses, and heat exposures on the
risk of neural tube defects in a Texas-Mexico border population. [Birth
Defects Res A Clin Mol
Teratol.](javascript:AL_get(this, 'jour', 'Birth Defects Res A Clin Mol Teratol.');)
2004 Oct;70(10):815-9.\
<http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=Abstract&list_uids=15468073>

**Other**

**Physiologic principles of exercise during pregnancy, UpToDate 15.2**

<http://www.uptodateonline.com/utd/content/topic.do?topicKey=antenatl/12515&selectedTitle=10~111&source=search_result>

Shepard 1986

Brent and Beckman 1994