"Women with cffDNA levels below the 5th percentile and above the 90th percentile quantified at 25 weeks' gestation are at increased risk of developing preeclampsia."
So, this is more of the targeting problem! Cell-free fetal DNA is broken-down trophoblastic cells from the placenta that are present in the plasma of pregnant women, and a bloodwork draw can provide enough to analyze not just the levels that are present, but also the DNA. The tests now on the market that allow identification of trisomies without amniocentesis or CVS, and that let us confirm fetal sex? Those tests are also using cell-free fetal DNA.
This study says that if cell-free fetal DNA levels were in the tails of the bell curve - if the number was in the bottom 5% or the top 90% of the distribution - your risk of preeclampsia was much increased. For high levels of fetal DNA, risk of severe preeclampsia was over 8x normal. For low levels of fetal DNA risk of mild preeclampsia was over 3x normal. And this goes back to what I said in this thread yesterday, because it really does seem to be a targeting issue. If the placenta implants to an average depth, you have an average amount of trophoblast, but if it implants less well than it should or more well than it should, you're a preeclampsia risk.