Hyperthyroidism is common among women of childbearing age. Whether or not you can get pregnant, when you can get pregnant, and what effects pregnancy will have on you and your fetus are all topics of concern for women with hyperthyroidism. 1. When can women with hyperthyroidism (hereinafter referred to as hyperthyroidism) become pregnant? Pregnancy can be considered after the thyroid function of hyperthyroidism is normal. First of all, hyperthyroidism can be divided into two main categories in terms of etiology. The first type is when the “motor” that synthesizes thyroid hormone malfunctions and the thyroxine receptor antibody is positive, stimulating the thyroid cells to synthesize thyroid hormone, which increases the level of the hormone in the blood and leads to hyperthyroidism. For women with this type of hyperthyroidism, it is best to get pregnant after the TRAb antibodies have completely turned negative and the medication has been stopped. If you want to get pregnant as soon as possible, and the TRAb does not turn negative within a short period of time, you can consider getting pregnant with medication. However, the smaller the dose of medication, the safer it is, so it is best to reduce the dose of medication to a smaller amount before considering pregnancy. It is also important to ensure that the serum FT3 and FT4 are in the normal range and the TSH is between 0,1-2,5. The second category is patients who have good “motor” function but whose thyroid follicles are destroyed by inflammation, such as subacute thyroiditis and Hashimoto’s thyroiditis. Their hyperthyroidism is a transient hyperthyroidism caused by the excessive release of thyroid hormones stored in the thyroid gland. These women will gradually return to normal thyroid hormones without medication or after short-term medication control. These women should wait until they are cured before getting pregnant. 2. What should I do if hyperthyroidism occurs after pregnancy? If you do not have hyperthyroidism but develop it after pregnancy and insist on pregnancy even after being informed of the risk of pregnancy, you need to take anti-thyroid medication, monitor thyroid function monthly, adjust the medication dose in time, and monitor the development of the fetus at the same time. It should be noted that some women with serum FT3 and FT4 within the normal range but serum TSH below the reference range may have subclinical hyperthyroidism. Some studies have found that this condition may be beneficial to the fetus and promote its growth and development, and pregnant women should not be overly concerned. It is just important to monitor more closely because severe hyperthyroidism has a risk of miscarriage. 3. What are the items that women with hyperthyroidism need to check during pregnancy? How often should they be checked? Hyperthyroidism during pregnancy can easily lead to miscarriage, while hypothyroidism can affect the growth and development of the fetus. Therefore, it is important to check regularly during pregnancy and adjust the dosage of medication in time to ensure that the thyroid function is within the normal range. It is best to check thyroid function once a month (to reach the standard as soon as possible, you can also recheck it 2 weeks to adjust the medication dose in time), mainly looking at the values and changes of FT3, FT4 and TSH. The doctor will adjust the dosage of medication mainly according to these three indicators. Especially FT4. FT4 should be maintained at the upper limit of normal value during pregnancy. This ensures that the fetus gets sufficient thyroid hormones, which helps its growth and development. FT4 requires above the midline and TSH must be kept below the midline, which is the 0,1-2,5 range. It is important to remind that during pregnancy, total T3 and total T4 will be 1,5 to 2 times higher than during non-pregnancy due to elevated TBG (thyroid binding globulin), which is normal, but free T3 and FT4 are not affected by elevated TBG during pregnancy, so total T3 and total T4 are generally not checked during pregnancy, but FT3 and FT4. antibodies like TPOAB and TGAb cannot be decreased in the short term. And clinical practice has found that the effect of these antibodies on pregnancy is a relationship between 1 and 0, that is, they either cause miscarriage or have no effect at all. The TRAb is related to whether to maintain the medication or not, so it can be reviewed once every 2-3 months. For those who are more concerned about this value, it is fine to check it once a month. 4. How to use medication during pregnancy for hyperthyroid women? There are two main types of medications for hyperthyroidism, methimazole and propylthiouracil. 90% of propylthiouracil binds to albumin and becomes a large molecule, which cannot pass through the placenta and has less effect on the fetus. Therefore, propylthioxypyrimethamine is preferred for the treatment of hyperthyroidism during pregnancy. The drug should also be used in the smallest effective dose, because 10% of propylthiouracil will still pass through the placenta, so the smaller the drug dose, the better, as long as it can control the nail function and keep it at the upper limit of normal. If you want to prepare for pregnancy during the course of methimazole treatment, you should gradually reduce the drug according to the recovery of methimazole, and you can consider pregnancy after switching to propylthiouracil when it is reduced to half a capsule. If pregnancy is discovered unexpectedly during the course of methimazole treatment, the treatment should be continued promptly by switching to propylthiouracil. During the first 1 week of pregnancy, the embryo is not yet in the womb and will not be affected by the drug. In contrast, at 2-4 weeks, if the embryo is affected, it will miscarry. In addition, if TSH is high, there is a risk of hypothyroidism, which can affect fetal brain development. The dosage of propylthiouracil should be reduced under the guidance of the doctor. If this is not enough, Eugenol should be added.