Jaw malformation can be detected by 4D ultrasound. Four-dimensional ultrasound is dynamic three-dimensional ultrasound, which can dynamically observe the growth and development of the fetus in multiple directions and angles, and is mainly used to detect cardiac malformations and malformations of large structures. The screening is usually done at 24 weeks to 28 weeks of pregnancy. Jaw malformations are usually manifested as narrow jaw, cleft palate, and tongue ptosis, which can be seen under 4D ultrasound. Mandibular malformations are a chromosome-related genetic disorder and are also mostly associated with maternal infection with cytomegalovirus, so if there is a certain genetic history, it is important to have a good general checkup before pregnancy, and amniocentesis can also be performed during pregnancy to detect abnormalities for early prevention and diagnosis.