When I was in the back of the ambulance when I broke my leg last year my BP was measured at 58/35mmHg. The paramedic said to her colleague, "I do NOT believe that BP."
Actually it doesn't normally dip that low, but I'd had a morphine reaction.
I've always been hypotensive. Always. I was given prophylactic aspirin throughout my pregnancy to prevent high blood pressure and I told them they were wasting their time. Even when I was heavily pregnant and ran from the staff carpark all the way to maternity because I was running late, my systolic BP still didn't get over 100.
The best thing you can do is stay hydrated.