The data do show a reduction in risk. It is a small reduction, but substantially larger than the risk reduction from LDA. Most women aren't going to get PE again in any case, of course, but all of us seem to value interventions that give us *some* little control over this condition, and a small reduction in risk overall is still worth having (given around 350,000 preeclamptic pregnancies annually, a reduction in risk from 14% to 12% would eliminate around 7000 cases - of course most of those aren't second pregnancies.)
viewtopic.php?f=28&t=40644 has more.
Also, exercise is still up in the air as a therapy, because of studies like this: http://www.ncbi.nlm.nih.gov/pubmed/19055653
