The thyroid gland is an endocrine organ located in the front of the neck and is responsible for the secretion of thyroid hormones, which control the rate at which energy is used, make proteins, and regulate the body’s sensitivity to other hormones. It is even more important for the fetus, as it can affect the development of the fetal nervous system in early pregnancy, and studies have proven that insufficient thyroid hormones in the mother during pregnancy can lead to a decrease in the child’s intelligence. Therefore, several hospitals have made thyroid function screening in early pregnancy a routine test. What should I do if I find low thyroid hormone levels during pregnancy? Early pregnancy requires TSH <2.5uiu/ml, mid-late pregnancy requires TSH <3.0uiu/ml, and as the weeks of pregnancy increase, the demand for thyroid hormones gradually increases. Therefore, once the tendency of hypothyroidism during pregnancy is detected, doctors will actively give treatment, and require pregnant women to review the thyroid function about every month, and gradually increase the amount of thyroid hormone supplementation as the need increases.