NT is a fetal posterior nuchal translucency scan. NT is an ultrasound test applied to observe the thickness of the fetal zona pellucida to generally screen for normal fetal chromosomes and abnormalities in body structure. The NT scan is an ultrasound examination to observe the thickness of the posterior nuchal translucency band during the 11th to 13th week of pregnancy to determine the fetal growth and development. It is important to note that the NT test is an abdominal ultrasound test and does not require an empty stomach or the need to hold urine. The normal value of NT test is <3mm, if the NT value is >2.2mm at around 11 weeks of gestation or >2.8mm at 13-14 weeks of gestation, the risk of abnormal fetal development is high. If NT value ≥3mm is detected around 13 weeks of pregnancy, it indicates that the fetus is at risk of Down syndrome or neural tube abnormalities such as spina bifida, hydrocephalus, anencephaly, etc. Non-invasive DNA screening can be performed under doctor’s guidance to clarify the diagnosis. If no chromosomal abnormality is found after the non-invasive DNA screening, the fetus can basically be determined not to have chromosomal abnormality, and regular maternity checkups can be performed. If chromosomal abnormality is found in the fetus after non-invasive DNA screening, further amniocentesis must be performed to clarify the diagnosis, and if necessary, the pregnancy should be terminated under the guidance of a doctor.