If a woman usually has more normal menstruation without symptoms such as abdominal pain or vaginal bleeding, she can start ultrasound examination at about 45 days after menopause, which is equivalent to more than 6 weeks of pregnancy, and at this time, a lot of things can be observed through ultrasound examination: 1) Whether the fetal sacs are inside the uterus or outside the uterus, and from this, it can be confirmed whether it is an intrauterine pregnancy or an ectopic one. Check the ovaries and fallopian tubes on both sides of the uterus to rule out problems such as ovarian cysts and hydrosalpinx; 2. Check the number of fetal sacs in the uterus, thus determining whether it is a single or multiple pregnancy. If it is a multiple pregnancy, you need to observe how many layers of chorionic villi are present to determine chorionicity, as there are differences in the principles of pregnancy management between monochorionic and dichorionic twin pregnancies. Multiple pregnancies may be detected at a greater number of gestational weeks, and some are determined to be monochorionic when ultrasound is performed at more than 6 weeks of gestation, and are found to be twin when ultrasound is reviewed at about 8-10 weeks of gestation; 3. Determine the size of the fetal sac in the uterus, whether the fetal buds and the fetal heart are in line with the week of gestation, and whether it is a live foetus, and assess the quality of the embryo. Fetal buds at more than 6 weeks of pregnancy are usually about 0.3-0.5 cm, and you can see the primitive heart tube pulsation. If you haven’t seen the fetal buds and heart, there may be a problem of late conception or poor embryo quality, and you need to check the ultrasound again in 1-2 weeks; 4. If you are a cesarean section and then conceive again, you need to see whether the position of the fetal sac is normal, and whether it has grown over the original cesarean section scar; 5. Check for the existence of chorionic villi Subchorionic hematoma or intrauterine dark area, to assess whether there is the manifestation of preeclampsia; 6, to check the development of the uterus, whether there is uterine fibroids, the size and location of uterine fibroids, whether it affects the continuation of pregnancy. Ultrasound is a common and important examination during pregnancy, which is helpful for understanding the growth and development of the fetus, and needs to be combined with the various stages of fetal development, and carried out several times in the corresponding time period.