S.T.
I don't think that there is really anything. The Dr's have some kind of test, but usually only do it if you are having contractions or other problems. I had contractions that would be 3-5 mins apart and regular and painful for over two months before I ended up being induced with both of my last two. So really the only signs are the contrations and/or your water breaking. Good Luck and I really hope that baby stays safe in your belly until at least 37 weeks.