All pregnant women who want to learn more about the health of their babies in the early period can have this test between the 11th-14th weeks of their pregnancy. Most babies are born healthy. The risk of giving birth to a baby with significant mental and/or physical problems is approximately 3% for all women. Some of these are due to a chromosomal or genetic diseases, and some are due to structural deformities. The most common chromosomal disease is Down syndrome. This syndrome causes learning difficulties and many medical problems. This test is recommended for all mothers, as every baby carries a small risk of being born with Down syndrome (one of every 700 babies born has Down syndrome). Interventional diagnostic tests such as “amniocentesis and CVS (chorionic villus sampling)” are used to detect fetuses with abnormal chromosomal structures. This test, which is used to assess the risk of Down syndrome, can especially help women over the age of 35 decide whether to have these interventional diagnostic tests or continue the pregnancy and also helps couples psychologically prepare for the birth of a problematic child. For this reason, screening tests that give reliable results in the early stages of pregnancy are needed as much as possible.