I did it vaginally and my water broke the next morning. I swear it was the EPO because labor didn't really start and I had to be induced. I wish I didn't do it.
I would feel better about taking it orally, but I would not take it vaginally unless you are trying to avoid an induction (41w+) and/or you don't plan to go med free.
I took it orally after my water broke, trying to get contractions to start and move things along and it didn't seem to do anything. (I was trying a lot of things so maybe it did help contribute, but it wasn't soon after taking the capsules.)