The range of TSH values during pregnancy is specified in relation to the number of weeks of gestation, and the reference range varies at different stages. TSH is a thyroid-stimulating hormone, which promotes the secretion of thyroid hormones, and the demand for thyroid hormones by the mother and the fetus will gradually increase during pregnancy, so the reference range of TSH values during pregnancy is not fixed, and the normal value in early pregnancy is 0.1-2.5 mIU/L, in mid-pregnancy is 0.2-3.0 mIU/L, and in late pregnancy is 0.3-3.0 mIU/L. If the TSH value is higher than the normal range, it suggests that the pregnant woman has hypothyroidism in pregnancy, and if the TSH value is lower than the normal range, it suggests that the pregnant woman has hyperthyroidism in pregnancy, and both of the above situations are unfavorable to the development of the fetus. When abnormalities occur in the results of the maternity test, pregnant women should seek medical treatment in time to avoid delaying the condition, which may lead to an adverse outcome of the pregnancy.