Low thyrotropin in pregnant women may be caused by diseases such as subclinical hyperthyroidism and clinical hyperthyroidism, which require targeted treatment under the guidance of a doctor, such as regular review and medication. Patients with subclinical hyperthyroidism may have low thyrotropin and normal thyroid hormone levels. Pregnant patients with subclinical hyperthyroidism generally do not need to intervene with antithyroid medications such as propoxypyrine because there is no evidence to confirm that subclinical hyperthyroidism is associated with adverse pregnancy outcomes. Patients with clinical hyperthyroidism need to be considered for treatment with antithyroid medications, such as propoxythiazide, to keep thyroid hormones within reasonable limits. Pregnant women presenting with abnormal thyroid-stimulating hormone levels are advised to visit a hospital for a doctor’s judgment and treatment under the doctor’s supervision.