What causes pregnancy hypothyroidism?

The causes of hypothyroidism during pregnancy include autoimmune diseases, iodine deficiency, history of thyroid surgery or radiation therapy, drug effects, and other factors. 1. Autoimmune diseases such as Hashimoto's thyroiditis are one of the common causes of hypothyroidism during pregnancy. When the immune system is abnormal, it produces antibodies against the thyroid gland, which can destroy thyroid tissue and affect the synthesis and secretion of thyroid hormones. 2. Iodine deficiency Iodine is an important raw material for the synthesis of thyroid hormones. If iodine intake is insufficient during pregnancy, it may lead to reduced thyroid hormone synthesis, which in turn may lead to hypothyroidism. Especially in some iodine deficiency areas, this situation is more likely to occur. 3. History of thyroid surgery or radiation therapy Previous partial or total thyroidectomy, or radioactive iodine therapy, can reduce thyroid tissue, resulting in insufficient thyroid hormone secretion, resulting in hypothyroidism during pregnancy.4. Drug effectCertain drugs may interfere with the synthesis or metabolism of thyroid hormones, resulting in hypothyroidism during pregnancy. Drugs such as lithium. 5. Other factors Genetic factors may increase the risk of hypothyroidism during pregnancy to some extent. In addition, as pregnancy progresses, the body's demand for thyroid hormones increases, and hypothyroidism may occur if the thyroid does not increase its secretion accordingly.