The triple test, also known as the triple screen, is a prenatal screening test that assesses three substances in the mother’s blood: alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3). It’s typically done between the 15th and 22nd weeks of pregnancy to recognize pregnant women whose fetus is likely to be impacted by trisomy 21 (Down syndrome).