During pregnancy, the thyroid gland and the levels of thyroid hormones it produces change, and thyroid disorders such as hypothyroidism may occur. Iodine deficiency is also a trigger for thyroid disorders, as the need for iodine increases during pregnancy and breastfeeding. Other causes of thyroid disorders include Hashimoto’s thyroiditis, an autoimmune thyroid disorder caused by an abnormal immune system that attacks and destroys thyroid cells. Changes in hormone levels during pregnancy can induce these autoimmune disorders and predispose to thyroid disease.