You are always going to find conflicting information for everything. Well maybe not always as there are certain things that no one argues are safe during pregnancy. But you can definitely always find a reason not to use/consume something (pregnant or not).
Personally, I always will look for info on trusted sources rather than just generic google. Failing that I will then examine reasons why something isn't recommended. From what I've read on google about wheatgrass is the reasons it's not recomended are generally due to a high risk of bacterial and mould contamination due to the growing conditions, and not anything to do with the plant itself.
For me, that means I would prefer to grow my own so I can be certain it isn't contaminated. Also I wouldn't use it to detox. You will have to decide for yourself whether the benefits outweigh the potential risks.
