Postpartum thyroiditis — a painless inflammation of the thyroid gland that develops within the first year after childbirth — often lasts from several weeks to several months. For some women, postpartum thyroiditis leads to long-term underactive thyroid (hypothyroidism).

The cause of this uncommon condition isn’t known. You may be at increased risk of postpartum thyroiditis if you have an immune system disorder, type 1 diabetes or a history of thyroiditis.

At first, the release of thyroid hormone and the related inflammation may cause signs and symptoms similar to those of an overactive thyroid (hyperthyroidism), including:

• Anxiety
• Irritability
• Rapid heartbeat or palpitations
• Unexplained weight loss
• Increased sensitivity to heat

A diagnosis of hyperthyroidism can be confirmed with blood tests. Treatment generally isn’t needed for mild signs and symptoms. If necessary, beta blockers may help reduce signs and symptoms — although beta blockers aren’t recommended for women who are breast-feeding.

Later, as thyroid cells become impaired by the inflammation, signs and symptoms of hypothyroidism may develop, including:

• Fatigue
• Weakness
• Unexplained weight gain
• Increased sensitivity to cold

As with hyperthyroidism, a diagnosis of hypothyroidism can be confirmed with blood tests. Treatment generally isn’t needed for mild signs and symptoms. If signs and symptoms are severe, thyroid hormone replacement therapy may be prescribed.

For the majority of women, thyroid function eventually returns to normal. However, some women who develop postpartum thyroiditis develop hypothyroidism and require lifelong thyroid hormone replacement therapy. Because hypothyroidism presents a significant risk to developing babies, it’s important to make sure the condition is under control before attempting another pregnancy.

source: mayo clinic