Amniocentesis is necessary for an NT value of 2.8 and can be performed under the supervision of a physician for screening. NT refers to the thickness of fetal nuchal translucency, ultrasound measurement of NT at 11~13+6 weeks of gestation can screen the risk of chromosomal disorders in the fetus, and the normal value is <2.5mm. when NT measurement is 2.8mm, it suggests that the risk of chromosomal disorders in the fetus increases, and it is necessary to follow the doctor's advice to perform prenatal diagnostic methods such as amniocentesis for definitive exclusion. During pregnancy, it is necessary to follow the doctor's instructions to have prenatal checkups on time and carry out appropriate screening tests, such as NT ultrasonography, Down's syndrome screening or non-invasive prenatal testing technology, amniocentesis, fetal structural anomalies screening, etc., to detect abnormalities in the development of the fetus at an early stage, and provide timely intervention and treatment in accordance with the doctor's instructions, so as to ensure the quality of the pregnancy.