NT is the abbreviation for the thickness of the nuchal translucency layer and is performed between 11-14 weeks of pregnancy. The thickness of the fetal nuchal translucency is measured by ultrasound. It is used to predict the risk of Down syndrome, congenital heart disease, and neural tube abnormalities. If the fetus is more than 14 weeks pregnant, the fetal nuchal translucency layer will be absorbed and disappear, so it is not useful to perform this test again. Therefore, it is important to do the NT test in time at the right gestational week. NT test does not require pregnant women to hold urine and fasting. During the examination, if the fetus is in a quiet state and the body position is not appropriate, which affects the operation during the examination, the pregnant woman should move or eat properly to induce the fetus to move and cooperate with the examination.