What do you take for your hypertension if you also sometimes go low in bp?

Maybe nothing: The goal in hypertensive treatment in pregnancy is not to get the BP as low in the normal range as possible. The goal is to avoid wide fluctuations and peaks that are potentially harmful. If the treatment is causing too low a bp, perhaps consideration should be given to reducing the dose or trying lifestyle changes (bed rest, for one) ins tread of higher dose meds.