If you are a female patient with hypothyroidism, aged around 20-30 years old, who has been taking thyroid hormones regularly for a long time and has had your thyroid function normalized by several re-tests. At this time, you are starting to have thoughts of having a small child. However, you are apprehensive that taking thyroid medication may have adverse effects on your fetus. Well, now I can tell you not to worry and not to panic. As long as your thyroid function is normal, then the effect on the fetus should be very minimal or no adverse effects. However, when you find out you are pregnant, you should go to the hospital as soon as possible to have your thyroid function (which is the level of free T3, free T4 and TSH) measured by a blood test. In most female patients, the amount of thyroid hormone needed increases during pregnancy, but the increased dose is different for each patient. Therefore, it is necessary to replace the insufficient amount of thyroid hormones in a timely manner according to the data from the laboratory tests. Generally, during pregnancy, at the beginning of the pregnancy and every month thereafter, thyroid function needs to be measured and then the dosage of medication needs to be adjusted according to the laboratory results. The whole process of adjusting the medication is very simple and can be solved well by a general endocrinologist. After delivery, the dose of thyroid hormone may be reduced back to the amount needed before pregnancy. Happily, during breastfeeding, the mother can take thyroid hormone while breastfeeding, without any worry that too much thyroid hormone will enter the little one’s body.