NT is a fetal nuchal translucency thickness scan. The NT test is a way to detect whether a fetus has Down syndrome. NT thickening is usually associated with fetal chromosomal abnormalities, and the higher the NT value, the higher the chance that the fetus has Down syndrome. If the NT value is 3-6mm, it means that the thickening is low and the risk of chromosomal abnormality is low; if the NT value is greater than 6mm, it means that the chance of fetal abnormality is high. When NT thickening occurs, non-invasive DNA testing and amniocentesis can be performed under the guidance of the doctor to clarify the diagnosis. If no chromosomal abnormality is found after the examination, it is basically certain that there is no chromosome number abnormality, and it is sufficient to have the labor checkups on time. If non-invasive DNA testing reveals chromosomal abnormalities in the fetus, further amniocentesis or chorionic villus biopsy must be performed to clearly diagnose the presence of Down’s syndrome, other chromosomal syndromes and heart problems. In serious cases, termination of pregnancy is required under the supervision of a doctor. Pregnant women need to undergo regular checkups to understand the growth of the fetus and rule out the possibility of abnormal development through comprehensive screening tests, and the development of the fetus should not be determined solely on the basis of NT thickening. In addition, in daily life, pay attention to stay away from radiation, chemicals and other toxic and harmful environments to ensure the normal growth and development of the fetus.