In the third month of pregnancy, i.e., when the first systematic examination of pregnancy is performed at 12 weeks, the main tests that need to be done include: i. Early Down’s syndrome screening, in which the thickness of the transparent layer of the baby’s neck is measured by ultrasound, and the baby’s nasal bone development is observed to assess whether the baby is at risk of Down’s syndrome. Second, general ultrasound examination, while doing NT examination, through ultrasound, to observe the baby’s physical development, whether it matches with the actual gestational week, and to detect whether the baby’s fetal heart and fetal movement are normal. Third, laboratory tests, if no laboratory tests have been performed before this, laboratory tests such as hepatitis B tri-system, syphilis spirochete antibody, AIDS antibody, liver function, kidney function, blood routine, blood sugar, blood type and thyroid function tests are needed at 12 weeks of pregnancy, if necessary. Fourth, measure the pregnant woman’s blood pressure, heart rate, body temperature, respiration and other vital signs.