The double marker test is a screening test that evaluates the levels of two particular indicators in the mother’s blood: free beta hCG and pregnancy-associated plasma protein A (PAPP-A). These are critical in determining the risks of various chromosomal disorders. The fetal liver and yolk sac release alpha-fetoprotein, whereas the placenta secretes human chorionic gonadotropin. These proteins’ levels can be used to assess the growing fetus’s health and identify disorders including Down syndrome (trisomy 21), trisomy 18, and neural tube abnormalities.