well, the current answer for your question would be NO.
As of this moment (that i know of) there is no solid data/ evidence showing that hyperbaric pressure causes harm to the fetus.
But there have been records of pregnant mother who go through hyperbaric treatment (i.e for carbon monoxide poisoning) and came out unscathed.
They did some studies using pregnant sheeps and the results were not in favour of fetal survival.
Anyway, all of this only applies if you are
certain that you are pregnant. if you are just going for a trip and hoping to get pregnant along they way....well by all means..have fun!
