Estimated detection rates of PE, at false-positive rate of 5% and 10% in screening by maternal factors with biochem- ical markers, are given in Tabl e 1 . The addition of maternal serum PAPP-A and PlGF to maternal factors improves the detection rates from 36% to 60% and from 33% to 43%, at false-positive rate of 5%, and from 51% to 74% and from 43% to 56%, at false-positive rate of 10%, for PE requiring delivery before 34 and 37 weeks’ gestation, respectively, but not for PE delivering before 42 weeks.