Hi Nicker:
I've been asked this question several times by women friends who have been (or currently are) pregnant since I owned my tub and I generally answer cautiously. For the most part, I think women in the first trimester of pregnancy should AVOID using a hot tub.
Why? Well, that's a good question. A 2003 study done by Li with Kaiser Permanente Research Institute in Oakland found that women less than 10 weeks pregnant "were twice as likely to suffer miscarriages if they took dips in hot tubs..." Some experts speculate that "high body temperatures caused by fever can lead to birth defects, especially those that prevent the skull or spinal cord from forming properly" which, ultimately, can cause spontaneous abortion of the fetus.
BUT, problems exist in Li's study in that he used "data mining" techniques to "pull" research data from an existing source and adapted the "pulled" data into his study's sample. What this means is that the data set he used wasn't specifically constructed to test a hypothesis concerning pregnancy and hot tubs. Instead, an existing data source generated from a generalized women's health questionnaire was used to support his conclusions. Many of the women in the study who used hot tubs and reported miscarriages also had other risk factors, including alcohol use. This lead at least one other researcher to conclude that Li's study was fundamentally flawed and that readers should draw no conclusions from it.
Nevertheless, it should make you pause. Invitro hyperthermia is certainly possible when a mother sits in higher temperature water for long periods of time. So, on one hand some experts say DON'T, but does this mean that pregnant women should avoid hot baths or showers too? Seems like a lot of research done by men makes being a woman a LOT harder. :-/
So, in my OPINION, pregnant women should avoid hot tubs above 100 degrees during the first trimester of pregnancy, with lower temperature use done sparingly. In the second and third trimesters, general use should be OK, but with "cooling off" periods completed after 20 minutes or less of use. Long duration exposures (more than 20 minutes) should be AVOIDED.
A lay person explanation of the study I referred to can be found
here, with the link to the original journal article being
here.
I'd suggest talking to your doctor about this study and see what he or she thinks.
BTW, in case you were wondering, I do have a medicine and epidemiological research background.
Hope this helps...
Drewski
