I have very low BP when pg. Usually it's right at 110/65-70. Last time around it was pretty much 90-100/50-55.
I stood up from my chair too fast to ask a co-worker a question. I made it to the doorway and had to sag against it or I was going to fall down. It was fairly noticeable - co-worker asked if I was ok, looked really worried. I managed to brush it off as best I could.
That's one way to nearly announce a pregnancy.