Mildly low thyroid stimulating hormone in pregnant women may be physiological reasons, regular review can be; may also be combined with hyperthyroidism, need to propylthiouracil and other methods of treatment. 1. Physiological: human chorionic gonadotropin level rises in early pregnancy, similar to the structure of thyroid stimulating hormone (TSH), can excite the TSH receptor antibodies on the surface of the thyroid gland, thyroid hormone rises, TSH is low, belongs to the physiological phenomenon, generally do not need special treatment, and can be reviewed regularly. 2. Pathological: pregnant women with low TSH may be hyperthyroidism, there may be excessive sweating, palpitations, hand tremors, diarrhea and other manifestations, in addition to low TSH, there may also be high T3, T4; combined with hyperthyroidism in pregnancy to the main treatment of medication, such as propylthiouracil, the side effects of its medication has a rash, itching, leukopenia, vomiting and diarrhea, and so on. Pregnant women with low thyroid stimulating hormone should go to the hospital, under the guidance of the doctor to identify the causes and treatment.