The drugs used to treat hyperthyroidism are methimazole and propylthiouracil. Propylthiouracil can combine with albumin to form large molecules that cannot pass through the placenta and have little effect on the fetus. Therefore, propylthiouracil should be preferred as the first choice for hyperthyroidism during pregnancy, and the smaller the dose of the drug, the better it is to prevent hypothyroidism in pregnant women and fetuses due to overtreatment. In addition, attention should be paid to monitoring thyroid function. Serum thyroid stimulating hormone and free thyroxine should be tested every 4 weeks or so to maintain thyroid function at the high end of normal. The dosage of medication that maintains FT4 at the upper limit of normal or mild hyperthyroidism is currently considered to be beneficial to the fetus and should not be a concern for pregnant women. Most of the treatment for hypothyroidism is replacement therapy, and the drug usually used is eugenol, which aims to make the serum TSH reach 1.0-2.5 as soon as possible, and the sooner the standard is reached, the better, as far as possible in the first trimester of pregnancy to ensure normal brain development of the fetus. As the duration of pregnancy increases, the demand for thyroid hormones by the mother and the fetus increases during pregnancy, so the thyroid function should be reviewed regularly (every 2-4 weeks) and the dosage of Eugenol should be adjusted by the endocrinologist, as long as the thyroid hormone level of the mother is normal, it will have no effect on the thyroid function of the fetus. In conclusion, if you suffer from thyroid disease during pregnancy, there is no need to panic and fear, please consult an endocrinologist in time.