NT is an important examination at this stage of pregnancy (11-13) weeks + 6 days, which mainly measures the thickness of fetal nuchal translucency through ultrasound, and is also an important indicator for determining whether there is any malformation in the fetus.NT1.3mm means the thickness of fetal nuchal translucency is 1.3mm, which belongs to the normal range. The likelihood of fetal malformation or chromosomal abnormality is small. the normal value of NT is 2.5mm or less, but NT1.3mm does not mean that the fetus is free from abnormalities, and should continue to be observed and undergo regular checkups. For example, Down’s syndrome screening should be performed at (15-20) weeks + 6 days of pregnancy to rule out the possibility of Down’s syndrome, and 4D ultrasound should be performed at 20-24 weeks to rule out the possibility of fetal malformation and to comprehensively determine the fetal development. In addition, NT ≥2.5mm is considered abnormal, suggesting chromosomal abnormalities or fetal malformations, such as cardiac malformations are more likely, and further prenatal diagnosis is required. Prenatal diagnosis includes non-invasive DNA testing and amniocentesis, which can clarify the presence or absence of fetal malformations. Further ultrasound examination is also needed, and the symptoms will be treated according to the findings and the cause of the disease. If the NT value is abnormal in repeated examinations, amniocentesis can be performed to determine whether there is any chromosomal abnormality.