Thank you!! I figured they wouldn't prevent, but I wanted confirmation. Your explanation was great!

Thanks for that simple reply! I've been trying to explain (mostly to my ILs) and couldn't figure out the right words! All well meaning on people's part but sometimes it's frustrating when it makes it seem as though *I'm* to blame for PE. I think you're reply will be perfect to help them understand symptoms vs cause

That would be great, unfortunately this is not the case. Since elevated bloodpressure is a symptom and not the cause of preeclamsia and related disorders, medication is more like damage control (treating a symptom is not curing it). However, It is very important to treat high bloodpressure to preven serious complications. Uncontrolled BP during pregnancy can lead to organ damage, stroke, placental abruption, and so forth.
Often bloodpressure can only be controlled to a certain extend. If you are maxed out on medication and the BP is still rising, delivery (along with other indicators)is imminent to prevent complications. The only cure of preeclampsia is birth (delivery of the placenta).

So, if you are on meds to control blood pressure during pregnancy, do they help prevent pre-e and/or HELLP? Will controlling the blood pressure prevent the onset of either illness?