If you haven't done a maternity reflexology course, I would just go gently on the endocrine system and the uterus. If she's less than 12 weeks, you need to decide whether you're happy to treat or not. There isn't really a problem, it's just that some organisations advocate not treating in the first trimester if you've not had additional specialist training. Personally I think that the first trimester is when you need it most!
Anyway, the points used to stimulate contractions don't fall within the scope of a standard treatment (unless you've done a bizarre course). They are Spleen 6, Bladder 60 and Blader 67.
Hope that helps