when can you test papp-a levels in pregnancy
1 Blood test. 2  This blood test measures the levels of pregnancy-associated plasma protein-A (PAPP-A) and the pregnancy hormone known as human chorionic gonadotropin (HCG). 3  Abnormal levels of PAPP-A and HCG may indicate a problem with the baby.f your screening test results are positive or worrisome, or you're at high risk of having a baby with Down syndrome, you might consider more testing to confirm the diagnosis. Your health care provider can help you weigh the pros and cons of these tests.