Graves disease is an autoimmune disease. The immune system normally protects the body from germs with chemicals called antibodies. But with an autoimmune disease, it makes antibodies that attack the body’s own tissues. With Graves disease, antibodies cause the thyroid gland to make too much thyroid hormone. This is known as hyperthyroidism. Extra thyroid hormone in the bloodstream leads to the body's metabolism being too active.
Hypothyroidism is when the thyroid gland does not make enough thyroid hormone. Congenital hypothyroidism is when the disorder is present in a baby at birth. If not treated, it can lead to serious health problems.
Postpartum thyroiditis happens when a person's thyroid becomes inflamed after delivering a baby, or having a miscarriage or abortion. It may first cause your thyroid to be overactive. But over time it leads to an underactive thyroid. This affects a small percentage of pregnant people.