Low blood pressure if first trimester

My blood pressure is consistently on the low side even before pregnancy. The only advice given by the gynae is to take your time to sit or stand up and be careful of giddy spells (if it happens just sit on the floor, don't try to grab anyone or anything in case it falls on you). In terms of health wise, there is no complications on you or the baby unless this is a drastic change cause by some medical conditions.