PAPPA and preeclampsia: Combined with PP13, PAPP-A, ADAM12, activin A, inhibin A, and uterine artery Doppler hemodynamics in the second trimester, the sensitivity for predicting preeclampsia can reach 60%-80%, and the specificity can reach 60%-80%; when the specificity of activin A combined with PI value in predicting preeclampsia was 90%, the sensitivity was only 57%.