Ultrasound is one of the most important and commonly used ancillary tests during pregnancy. When many pregnant women go to the hospital for obstetric examinations, they are told by the doctor that they need an ultrasound examination. It can be confirmed here that multiple ultrasound examinations during pregnancy do not have any significant adverse effects on the development of the baby. Ultrasound is currently one of the safest, most effective, non-toxic and repeatable forms of ancillary examination, and is widely used in obstetrics. If there are no significant abnormalities during pregnancy, ultrasound examinations should be performed mainly once at about 6-8 weeks, 12 weeks, 20 to 28 weeks, 32 weeks and 38 weeks of pregnancy, and the number of ultrasound examinations should be increased at any time if there are abnormalities.