Punctate calcification of the fetal nasal bone is mainly caused by chromosomal abnormalities or viral infections during pregnancy that affect fetal development. 1. Chromosomal abnormality: it will affect the development of fetal nasal bone and appear the phenomenon of punctate calcification, which belongs to a kind of developmental abnormality. If the ultrasound shows that the nasal bone of the fetus is calcified, then it is necessary to do amniocentesis to screen the chromosomes, and if the chromosomal abnormality is caused by the chromosomal abnormality, we should carefully consider whether to induce labor. 2. Viral infections: Herpes simplex virus or rubella virus may also cause abnormal development of the fetal nasal bone, and blood tests can be performed to determine this. In addition, the ultrasound should be repeated in two weeks to see if there is any recovery of the punctate calcification of the nasal bone, and then determine whether or not to intervene. In addition, it is important to pay attention to regular pregnancy checkups, and if there are any abnormalities, timely treatment and intervention are needed to avoid delaying the condition.