What causes hypothyroidism in pregnancy?
Hypothyroidism in pregnancy is usually caused by Hashimoto’s disease and occurs in one to three of every 1,000 pregnancies.3 Like Graves’ disease, Hashimoto’s disease is an autoimmune disorder. In Hashimoto’s disease, the immune system makes antibodies that attack cells in the thyroid and interfere with their ability to produce thyroid hormones. White blood cells also invade the thyroid and decrease thyroid hormone production. Hypothyroidism in pregnancy can also result from existing hypothyroidism that is inadequately treated or from prior destruction or removal of the thyroid as a treatment for hyperthyroidism.
