Folic acid supplementation from the third trimester to the third trimester of pregnancy, after the 14th week of pregnancy to increase food rich in protein, calcium, iron and various vitamins, and before the 20th week of pregnancy it is recommended to increase food rich in iodine. 1. Folic acid: it is generally recommended to take folic acid 0.4-0.8mg orally until the first trimester of pregnancy to prevent fetal neural tube abnormalities, if there is a history of neural tube abnormalities in childbirth, should be under the guidance of the obstetrician to increase the dosage of folic acid, do not add, so as not to cause adverse effects. 2. Protein, calcium, iron and various vitamins: after 14 weeks of pregnancy, with the accelerated growth and development of the fetus, it is necessary to increase food rich in protein, calcium, iron and various vitamins, such as eggs, milk, lean meat, fish and shrimp and a variety of green leafy vegetables, and routine supplementation of calcium. 3. Iodine: before 20 weeks of pregnancy, all the thyroid hormones of the fetus come from the mother, iodine is an important raw material for the synthesis of thyroid hormones, iodine-rich foods should be increased, such as deep-sea fish, algae and so on. For iron supplementation, it should be added at the right time under the guidance of the doctor according to the results of routine blood tests and ferritin during pregnancy. It is recommended that regular obstetric examinations be conducted during pregnancy, and under the guidance of the obstetrician, the nutrition required at each stage should be supplemented in a timely manner.