If a pregnant woman has hypothyroidism, it is too late for her to take medication at 5 weeks of pregnancy if the fetus develops normally, but it is too late for her to take medication if the fetus develops abnormally. Five weeks of pregnancy belongs to the early stages of pregnancy, in this period the fetus needs thyroid hormone is completely dependent on the mother, if the mother suffers from hypothyroidism and lead to insufficient secretion of thyroid hormone, it will affect the brain development of the fetus. If the mother’s hypothyroidism is mild and there is no abnormality in the development of the fetus, it is not too late to take medication. However, if the development of the fetus has been affected, then the effect is irreversible, and it is too late to take medication at this time, you can determine whether the development of the fetus is normal through adequate pregnancy examination. After the discovery of hypothyroidism in the fifth week of pregnancy, it is recommended to take medication under the guidance of a doctor to supplement thyroid hormones in order to restore the function of the thyroid gland, and after the normalization of the thyroid function, it is necessary to have regular rechecks.