Prenatal ultrasonography is a major screening of the fetal nervous system, digestive system, urinary system and heart through ultrasound. Prenatal ultrasonography can be divided into routine prenatal ultrasonography, systemic fetal ultrasonography and targeted ultrasonography. 1. routine prenatal ultrasonography: this examination is mainly used to measure the fetal gestational age and to conduct rough screening for serious fetal lethal malformations, usually performed at 11-13 weeks of gestation; 2. systemic fetal ultrasonography: the examination can screen for fetal size and six types of lethal malformations as stipulated by the Ministry of Health. Screening for anencephaly, severe brain expansion, severe open spina bifida, severe chest and abdominal wall defects and visceral ectopia, single-chambered heart, and lethal chondrodysplasia. This test is performed at 18-24 weeks of gestation, when the fetal fluid is the most abundant, the mobility is greater, and the fetal structures are more clearly displayed; 3. Targeted ultrasound examination: it can be carried out on the basis of the first two tests to systematically observe the main anatomical structures of the fetus to predict whether the size of the fetus matches the actual gestational week, and to systematically screen for serious structural malformations, usually at 32-36 weeks of gestation . In addition, although ultrasonography is currently the most effective method to screen for fetal structural malformations, there is a wide variety of fetal malformations, some of which cannot be identified by ultrasound detection. Therefore, it is recommended that pregnant women actively undergo prenatal checkups, maintain good lifestyle habits on weekdays, pay attention to a healthy diet, and exercise in moderation to improve their body’s immunity and reduce the birth of diseased fetuses.