My BP averaged around 90-100/60 throughout my PG. Like Alan said in the first trimester its common & mine stayed low. I would have dizzy spells & fainting. I found that I needed to increase my fluid intake so I would drink 2 litres of water a day & more fluids if possible. I made sure that I took water everywhere & drank constantly. I felt like I was drowning sometimes, but it was important. On bad days I would sip poweraide as well and that helped tremendously.