PGF and preeclampsia: A prospective, multicenter, observational PROGNOSIS study found that an sFlt-1/PlGF ratio ≤38 had a negative predictive value (NPV) (no preeclampsia diagnosis) of 99.3% (95% confidence interval [CI], 97.9–99.9) in the subsequent week for pregnancy between 24 and 36 + 6 weeks.