Postpartum thyroiditis is an inflammation of the thyroid gland that appears 1 to 8 months after giving birth and affects about 8 percent of women who delivered within the previous year. Thyroiditis can cause stored thyroid hormone to leak out of the inflamed gland and raise hormone levels in the blood.
Postpartum thyroiditis is believed to be an autoimmune condition and causes mild hyperthyroidism that usually lasts 1 to 2 months. Many women then develop hypothyroidism lasting 6 to 12 months before the thyroid regains normal function. In some women, the thyroid is too damaged to regain normal function and their hypothyroidism is permanent, requiring lifelong treatment with synthetic thyroid hormone.
Postpartum thyroiditis sometimes goes undiagnosed because the symptoms are mistaken for postpartum blues—the exhaustion and moodiness that sometimes follow delivery. If symptoms of fatigue and lethargy do not go away within a few months or a woman develops postpartum depression, she should talk with her doctor. She may have developed a permanent thyroid condition and will need to take medication.