If hypothyroidism is diagnosed during pregnancy, it is recommended to continue supplementation with levothyroxine and other medications after delivery, and to review the blood thyroid stimulating hormone TSH. The cause of hypothyroidism during pregnancy may be due to the increased demand for thyroid hormones by the mother and fetus during pregnancy and insufficient secretion by the mother; it may also be due to hypothyroidism caused by previous surgical removal of the thyroid gland, thyroiditis, and other diseases. It is usually necessary to increase the dosage of levothyroxine, etc. during pregnancy, and continued maintenance medication is recommended after pregnancy. For those with hypothyroidism already diagnosed before pregnancy such as surgical thyroidectomy and thyroiditis, the dosage of levothyroxine and other medications should be reduced to pre-pregnancy levels after delivery, and thyroid-stimulating hormone TSH levels should be rechecked at 6 weeks postpartum. In the case of clinical hypothyroidism diagnosed during pregnancy, a non-pregnant dose of levothyroxine may be given postpartum. Specific medication needs to be judged according to the condition and thyroid stimulating hormone TSH level. Clinical hypothyroidism requires prompt medical attention. Levothyroxine should be used under the supervision of a clinician and should not be taken on its own.