NT is the thickness of fetal nuchal translucency under ultrasound, the value of 1.6mm is within the normal range, which means that the embryo is less likely to have Down’s syndrome. NT is the thickness of fetal nuchal translucency under ultrasound, it is a common screening test for Down’s syndrome, the normal NT value is <2.5mm, 1.6mm is within the normal range, which means that the fetus is less likely to have Down's syndrome, the pregnant woman should not worry too much, she can continue the pregnancy. Under normal circumstances, the NT test can be performed at the hospital between 11-13 weeks plus 6 days of pregnancy, but the results may be inaccurate if the test is missed. If the NT test is performed before 11 weeks of pregnancy, the baby is too small to be seen during the ultrasound; if the test is performed too late, the fetal lymphatic system will absorb too much fluid, making the test results inaccurate. Generally NT value ≥3mm is NT thickening, which indicates that there may be abnormal fetal development. The larger the NT value, the higher the chance of fetal abnormality risk, and the possibility of fetal Down syndrome or congenital heart disease or neural tube malformation needs to be considered, and doctors often suggest women to do further amniocentesis and cytology examination for clear diagnosis. If some pregnant women miss the best time for NT test, there is no need to worry too much, there is also Down's syndrome screening and major teratology test in the middle term, which can also achieve more in-depth teratology screening. In addition to this test, pregnant women should continue to improve other tests, such as non-invasive DNA and 4D ultrasound, etc. They should have regular maternity checkups during pregnancy and follow the physician's instructions to pay attention to rest, balanced nutrition and proper exercise.