We were told at 12 weeks that they could be 90% sure it was a boy.
Confirmed at 19 weeks.
Normally I would have taken the prediction at 12 weeks with a grain of salt, but as I had the u/s done at a clinic who only do female u/s (Ob & Gyn) and we actually had the professor do ours, I was a little more confident.
Anyway I guess we won't know for sure for another 5 1/2 weeks or so!