The first trimester of pregnancy refers to the period before the 13th week of pregnancy, i.e. the first 3 months of pregnancy. It is an important period for the formation of the embryo and the differentiation of the fetal organs, which can be affected by various factors such as unstable fertilization of the egg and even miscarriage. Therefore, there are some aspects that need special attention and necessary examination items in the early stage of pregnancy. 1, general precautions: pay attention to rest, ensure sufficient sleep, maintain a relaxed state of mind; diet should not be large fish and meat; avoid large movements, such as carrying heavy objects, strenuous exercise, try not to have intercourse; avoid colds and fevers, quit smoking and alcohol, refuse poison, do not contact with psychotropic drugs, such as colds require drug treatment, need to consult a specialist; reduce exposure to radiation. For pregnant women who like small animals, such as cats or dogs, care should be taken to reduce contact during pregnancy, preferably without contact, because small animals may carry parasites, such as Toxoplasma gondii, which may lead to infertility or the appearance of miscarriage. 2. Early pregnancy checkup: The first maternity checkup during pregnancy is from 6 weeks to less than 13 weeks, during which pregnant women need to establish a pregnancy health handbook and do relevant examinations. Blood will be drawn to check for anemia, iron deficiency, calcium deficiency, abnormal liver and kidney function, blood sugar and thyroid function for timely and effective treatment. In particular, abnormal blood glucose, such as diabetes combined with pregnancy, can be very harmful to both mother and child, aggravating the damage to the mother’s pancreatic function during pregnancy and increasing the risk of hypertension during pregnancy; for the fetus, the long-term hyperglycemic environment slows down its lung maturation and increases the risk of respiratory distress, lung infection and hypoglycemia after birth, requiring early treatment and control; and low thyroid hormone levels (hypothyroidism) can seriously affect the fetus’ intelligence If the level of thyroid hormone is low (hypothyroidism), it may affect the fetus’ intelligence and bone development and risk cretinism; if it is high (hyperthyroidism), it may lead to miscarriage in early pregnancy and mood swings of the pregnant mother.