If the NT value is 1.3mm, it means there is no abnormality and the pregnant woman should not worry too much and continue the pregnancy. NT is a method to assess whether the fetus is likely to have Down’s syndrome by measuring the thickest subcutaneous echogenic layer of the fetal neck through ultrasound. If the NT value ≥3mm is associated with fetal chromosomal abnormalities, further chromosomal testing, such as amniocentesis or non-invasive DNA, is needed to rule out whether the fetus has chromosomal abnormalities. The best time for NT examination is between 11-14 weeks of pregnancy and can be measured by transabdominal or transvaginal ultrasound. NT examination does not require fasting or urine holding, but it is related to menstrual cycle, weight, height, exact gestational week and gestational age size. Usually, you need to take rest and avoid intercourse and exposure to harmful substances in early pregnancy.