Postpartum Thyroiditis and Its Relationship With Autoimmunity

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The thyroid and pregnancy have a direct relationship that not everyone is aware of. During pregnancy and after delivery, the mother’s thyroid gland goes through several hemodynamic, metabolic, and immunologic changes. Any small thyroid dysfunction if not detected on time can lead to serious thyroid and pregnancy disorders in the short or long term.

Thyroid and Pregnancy

During pregnancy, the mother’s thyroid gland ideally should increase its thyroxine production by 30% to 50%. The right balance and proper functioning ensure the correct brain development of the fetus and its nervous system. Often a slight imbalance can trigger the onset of thyroid problems, which can lead to a risk of miscarriage or preterm birth. Since thyroid and pregnancy have an obvious relationship, it’s a common practice to monitor the thyroid profile periodically throughout pregnancy.

Postpartum Thyroiditis

After delivery, especially in the first year of the postpartum period, there could be an onset, exacerbation, or relapse of autoimmune diseases. The most common autoimmune thyroid disease postnatally is postpartum thyroiditis.

Postpartum thyroiditis is a transient or permanent thyroid dysfunction syndrome that occurs in the first year after delivery. It is based on an autoimmune inflammation of the thyroid. This thyroid disorder may also occur after the loss of pregnancy at 5–20 weeks gestation.

Most women, who develop postpartum thyroiditis, may take 12 to 18 months from the start of the symptoms for their thyroid function to return to normal. But some women may develop permanent thyroid dysfunction.

What Causes Postpartum Thyroiditis?

During postpartum, when antithyroid antibodies attack the thyroid, it causes the thyroid to become inflamed, leading to postpartum thyroiditis.

The reason why antibodies attack the thyroid is still unknown. However, it is believed that women who develop postpartum thyroiditis may have an underlying autoimmune thyroid condition. However the symptoms are not seen.

During pregnancy, several changes in the immune system take place that makes the pregnant woman have an enhanced state of immune tolerance. During the postpartum period, this immune tolerance is slowly lost which can be accompanied by the beginning, relapse, or worsening of autoimmune thyroid disorders. This rebound reaction to this pregnancy-associated immune suppression aggravates the autoimmune syndrome after delivery, leading to postpartum thyroiditis.