Is prune juice safe to drink during pregnancy.

Depends: If you are constipated, it should help you have a bowel movement. If you have too many bowel movements, that may not be so great. So, depends what you are using it for? As with anything, less is more. So if you don't need to use it, then not to worry. If you do, then proceed using a little to see it's effects on you. One good thing is that is is a natural food. Just don't overdo!