Twelve weeks of pregnancy is the 3rd month of pregnancy, i.e. early pregnancy, a critical period for the development of the fetal nervous system. According to the calculation of 1 month and 4 weeks, 12 weeks of pregnancy is 3 months of pregnancy, but in the actual month, 1 month is more than 4 weeks, so 12 weeks of pregnancy may be less than 3 months. Twelve weeks of pregnancy is the early stage of pregnancy, during which early pregnancy reactions such as nausea, vomiting and fear of greasy food will occur. Therefore, early pregnancy should pay attention to a light diet, prohibit sexual intercourse, and pregnant women themselves should regulate their emotions and psychology. In addition, early pregnancy is a critical period for the development of the fetal nervous system, so attention should be paid to folic acid supplementation and avoid exposure to ionizing radiation and other harmful chemicals to avoid abnormal fetal development. Patients in early pregnancy may have large mood swings, and the surrounding relatives and friends should give more encouragement and support to help pregnant women regulate their emotions.