The Triple Marker Test is a prenatal blood test usually performed between the 15th and 20th weeks of pregnancy. It measures the levels of alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG), and unconjugated estriol (uE3) in the mother's blood to assess the risk of certain fetal conditions, including Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18), and neural tube defects like spina bifida. While it does not diagnose these conditions definitively, the test provides valuable risk assessment, guiding whether further diagnostic procedures may be needed for a more conclusive evaluation.