Thyrotropin (TSH) is one of the hormones secreted by the anterior pituitary gland and its main function is to control and regulate the activity of the thyroid gland. Measurement of TSH in serum (plasma) is one of the most important indicators for the diagnosis and treatment of hyperthyroidism and hypothyroidism, as well as for the study of the hypothalamic-pituitary-thyroid axis. High TSH in pregnant women can be caused by an underactive thyroid gland or by an enlarged pituitary gland during pregnancy. The most common cause is an autoimmune thyroid disease, also called Hashimoto’s thyroiditis, in which long-term inflammation causes destruction of thyroid cells, resulting in a deficiency of thyroid hormones and an increase in TSH secretion, and, to a lesser extent, due to iodine deficiency. If TSH is less than 4.0mU/L, it is normal; if TSH is greater than 4.0mU/L and less than 10.0mU/L, thyroid autoantibodies TPO or TGAb are negative, close observation is sufficient; if TPO or TGAb is positive, treatment needs to be initiated; if TSH is greater than 10.0mU/L, hypothyroidism treatment needs to be taken. Elevated TSH can affect the normal development of the fetus, especially the development of the nervous system, and may increase the chance of adverse pregnancy for pregnant women, such as miscarriage, or stoppage of pregnancy, etc. It should be paid enough attention and needs to be closely observed. Therefore, hypothyroidism is more harmful and can easily cause intellectual and developmental disorders in infants. Therefore, the examination of thyroid function is currently used as a prenatal screening program, and pregnant women must pay attention to prenatal examinations and deal with abnormalities in a timely manner.