The pregnancy sac can be seen in the uterine cavity through ultrasound on the 40th day of pregnancy, however, the fetal heart and buds cannot be seen at this time, so you can wait until about 50 days for ultrasound examination to observe the fetal heart and buds. Ultrasound examination at 5-6 weeks of early pregnancy can roughly see the position of the embryo sac in the uterus, and can also see the number of embryos; while ultrasound examination at 6-8 weeks of pregnancy can see the fetal heart and buds, confirming that it is an intrauterine pregnancy. Ultrasound is performed at 11-13 weeks of pregnancy to check the development of the fetus and whether there are any abnormalities. A 4D ultrasound is recommended at 21-24 weeks of pregnancy to rule out fetal abnormalities. Most pregnant women will have early pregnancy reaction on the 40th day of pregnancy, and they will have acid reflux, nausea and vomiting when they get up in the morning. If the reaction is mild, you don’t need to pay too much attention to it. If the reaction is more serious, you need to go to the hospital for examination and continue to take oral folic acid.