Can my pregnant wife do the cold water challenge or is it to much shock on her body?

It's ok: Heat, such as in a hot tub or sauna, over 104 degrees has been associated with miscarriage, but cold should not have any effect on the baby as long as the mother does not become hypothermic. This assumes that the cervix is still completely closed and the amniotic fluid sack is intact, which they are in a normal early pregnancy.

Best not to: Why chance it, as even young healthy, non pregnant people can sometimes have reactions to severe changes in temperatures, and you wold not want to chance a possible reaction that could in any way harm the baby. You do it and have her video tape it with a warm sweater on herself. good luck.