Quoting Mommytobetoababyboy :" I am going to a spring tomorrow. It is really cold water. Am I allowed to get in it while I am pregnant? ... [snip!] ... I am pregnant? Or will my baby go into shock? I am 27 weeks pregnant and I dont wanna do anything that risks my pregnancy?"
My OB told me that once you hit your second trimester, your baby in the womb has it's own temperature regulation. She said as long as the water wasn't freezing cold or as long as I didn't go in a hot tub, it was fine! I would call yours to get their opinion, though.