Pregnancy Associated Plasma Protein A test is performed on a sample of blood to measure level of Pregnancy Associated Plasma Protein A in blood.It is performed to detect Pregnancy. Also known as PAPPA test. (PAPP-A) is a protein produced first by the growing placenta in the mother’s womb. This is usually done first trimester screening is a along with hCG and nuchal translucency test that are used to evaluate the risk that the fetus,inside the mother has a chromosomal disorder like Down syndrome (trisomy 21) or Edwards syndrome (trisomy 18).