They don't know why it happens (all those "risk factors" don't seem to work all that well for predictions), nor it can be taken care of completely. I assume they found protein in urine that led the doctor to think it may be preeclampsia.
Bed rest, more water, and less salt should somewhat help. Hugs to her!
"Life isn't about waiting for the storm to pass: it's about learning to dance in the rain..."
"When we are no longer able to change a situation - we are challenged to change ourselves."
"How people treat you is their karma; how you react is yours."