The causes of high thyroid hormone in pregnant women are mainly the following two aspects: 1. The basic metabolic rate of pregnant women increases, and both the mother and the fetus need various hormones to maintain the normal growth and development of the human body during pregnancy, so the basic metabolic rate in the body of pregnant women increases, and their needs for various substances need to be doubled, which leads to high thyroid hormone in pregnant women themselves. 2. The endocrine system of pregnant women themselves changes to a certain extent during pregnancy. The demand for thyroid hormone is high, and the demand for other hormones such as adrenal hormone and progesterone will also increase. Some pregnant women may have symptoms of high blood sugar during pregnancy, which are normal physiological reactions and will gradually return to normal values after delivery. If the mother develops a serious illness, she will need immediate medical attention.