I am 36 weeks, and am Rh-. I declined the Rogham, since I know it's unnecessary and only important if my baby is a Rh+.
Anyway, I had read up a lot about it, and had done the same during my first pregnancy, but since my son was O- i didn't take the later shot. I know that the mother's and baby's blood don't mix, unless there was a major trauma or an accident etc.
Today, however, I accidentally got kicked on my belly, by my cousin's daughter who was playing and was trying to do a hands stand and even though it was NOT that painful, but did shock me and has caused me some soreness and I have been worried for a few hours now, wondering if that would have caused blood mixing, and if I should go in to take the shot. =(