What Is the Double Marker Test? The Double Marker Test is a blood test done in early pregnancy. It helps doctors know if your baby has a chance of genetic problems, like: Down syndrome (Trisomy 21) Trisomy 18 (Edwards syndrome) This test does not harm the baby. It only gives a risk score to help parents make the right decision. https://babybloomivf.com/double-marker-test-cost-risks-importance-in-pregnancy