Ultrasound can find out about 40 days of pregnancy, because the pregnancy sac can enter the uterine cavity after about 40 days of pregnancy, and it can be checked by ultrasound, and it is recommended to go to a regular hospital for checkup, which is relatively safe. After pregnancy, pay attention to sufficient rest, strengthen the diet and nutrition, which will help the growth and development of the fetus. Ultrasound examination during pregnancy is divided into the following stages: 1. The earliest ultrasound examination is carried out after 6 weeks of menopause, in addition to routine gynecological examination, it is also necessary to determine whether intrauterine pregnancy is normal. When no pregnancy can be detected in the uterine cavity and an abnormal mass is detected outside the uterine cavity, it should be combined with other clinical manifestations as well as laboratory test results to consider whether it is an ectopic pregnancy; 2. Ultrasound is conducted again at about 16 weeks to find out about the growth and development of the fetus; 3. Ultrasound is reviewed again at about 28 weeks to have a clear understanding of the development of the fetal tissues and organs, and to find out whether there are any malformations in the fetus, and in case of If there is any malformation, relevant treatment should be carried out under the guidance of the doctor; 4. From 36 weeks of pregnancy to the expected date of delivery, ultrasound should be carried out again to clarify the amount of amniotic fluid, the function of the placenta, and whether there is any umbilical cord around the neck of the fetus, and so on. At the same time, it can estimate the weight of the fetus, clarify the change of fetal position, and can predict whether the pregnant woman can have a natural delivery.