Ultrasound during pregnancy is a concern for many pregnant women, and even some clinicians believe that the fewer ultrasounds during pregnancy, the better. In fact, ultrasound is a kind of ultrasound, intermittent pulse emission, it does not have biological effects like X-rays, in general, it is not so harmful to pregnant women or fetuses, so it is not necessary to be so afraid of ultrasound examinations during pregnancy. On the contrary, the consequences of missing many diseases because of scrupulous ultrasound examinations can be very serious. In recent years, the incidence of ectopic pregnancy, embryonic abortion and birth defects in infants has been increasing year by year, and ultrasound examinations can rule out and screen for these diseases in a timely manner. In early pregnancy, ultrasound examination can be done between 34-40 days of pregnancy to understand the location of the gestational sac, so as to detect and exclude ectopic pregnancy early; 50-70 days of pregnancy is the period of embryonic abortion, ultrasound examination can understand the growth of embryo, diagnose the embryo stopping development in time, and perform clearance as early as possible to reduce the impact on re-pregnancy; 11w-13w, 22-26w and 30-32w of pregnancy Ultrasound is essential to screen for most fetal malformations and reduce birth defects. In addition, if there is a history of spontaneous abortion or fetal malformation, or if there is abnormal fetal movement or abnormal amniotic fluid during pregnancy, the number of ultrasound examinations should be increased accordingly to ensure optimal birth and fertility.