Thickening of the fetal neck fold on 4D ultrasound may be due to abnormal fetal development, among other reasons. Fetal neck fold thickness (NF) is an ultrasound genetic marker screening in mid-pregnancy, with a normal value of <6mm. When 4D ultrasound suggests thickening of the fetal neck fold, it suggests that the fetus is at increased risk of chromosomal disorders, and further prenatal counseling and prenatal diagnostics, such as amniocentesis, are required to clarify whether there is any combination of chromosomal disorders in the fetus as directed by the doctor. During pregnancy, it is necessary to follow the doctor's instructions to carry out on-time and standardized obstetric examination, which can timely detect complications and complications during pregnancy, and follow the doctor's instructions to carry out on-time and relevant malformation examination, such as fetal nuchal translucency thickness measurement, Down's syndrome screening, amniocentesis and fetal structure ultrasound screening, etc., in order to early detection of fetal abnormalities, and to ensure the quality of pregnancy. 4D ultrasound fetal nuchal folds thickening need to be further examined under the guidance of a doctor.