The precautions for ultrasound when you are just pregnant are: 1. Pay attention to the time of the examination, which is usually done at about 40 days of pregnancy, when your menstruation is usually regular and your cycle is 28-30 days, you can do ultrasound at 40 days of pregnancy. If your period is irregular, you can do ultrasound from the day of conception, about 25 days. 2. Hold urine before the examination to fill the bladder, because the size of the uterus does not change much in early pregnancy, so you also need to hold urine for the examination. 3. If the location is normal, observe the shape of the gestational sac, measure its size and see if there is a yolk sac growing. At 45 days of gestation, we should observe whether there is a fetal bud and whether there is a fetal heartbeat. 4. If no gestational sac is found in the middle of the uterine cavity, we should focus on the bilateral horn of the uterus and the cervix, as well as the bilateral adnexal areas to see whether there is an echo of the gestational sac in these areas to exclude ectopic pregnancy.