Conclusion
Adding PlGF or replacing PAPP-A with PlGF in the current first trimester
combined test for trisomy 21 screening in screening centres performing
both trisomy 21 and preeclampsia screening would not significantly
improve the detection rate for trisomy 21 but would increase the screen
positive rate if PAPP-A is replaced by PlGF or result in a small
reduction in the screen positive and false positive rates if PlGF is
added to the combined test.