In medical calculations of pregnancy, 4 weeks is a gestational month. For women who usually have regular menstrual cycles, the pregnancy is calculated from the first day of the last menstrual period. Counting from this day, the entire pregnancy lasts about 40 weeks, which is 280 days and 10 gestational months. However, the fetus matures after it reaches 37 weeks and it is normal to deliver between 37 and 42 weeks of pregnancy. Usually when a woman is about 6 weeks pregnant, due to changes in hormone levels in her body, she may experience a series of early pregnancy symptoms, such as nausea and vomiting, breast swelling and pain, and body weakness. At 8 to 10 weeks, the HCG value reaches its peak and then lasts for more than 10 days, and then gradually decreases at around 12 weeks, and the symptoms of early pregnancy reaction will be relieved. Throughout pregnancy, women need to go to the hospital regularly for various pregnancy tests, such as NT test at 11~13 weeks plus 6 weeks of pregnancy, Down’s syndrome screening at 15~20 weeks of pregnancy, and fetal structural abnormality screening at 20~24 weeks of pregnancy.