Postpartum Thyroiditis: When Thyroid Goes Haywire After Birth

Postpartum thyroiditis is thyroid inflammation that occurs in the first year after birth, affecting up to 10% of women. It often causes a hyperthyroid phase (anxiety, racing heart) followed by a hypothyroid phase (fatigue, depression). Most resolve, but some develop permanent hypothyroidism.

The two-phase pattern

Postpartum thyroiditis often follows a predictable course.

  • Hyperthyroid phase (1-4 months postpartum): anxiety, weight loss, racing heart.
  • Hypothyroid phase (4-8 months postpartum): fatigue, depression, weight gain.
  • Most women return to normal thyroid function within a year.
  • About 20% develop permanent hypothyroidism and need ongoing treatment.

Track how you feel and spot the pattern

PhaseBloom logs your symptoms and mood against your cycle in seconds a day, so you can see which days hit hardest and prepare before they arrive.

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Track how you feel and spot the pattern

PhaseBloom logs your symptoms and mood against your cycle in seconds a day, so you can see which days hit hardest and prepare before they arrive.

Start tracking free

Frequently asked questions

What causes postpartum thyroiditis?

It is an autoimmune inflammation of the thyroid triggered by the immune system shift after pregnancy. Women with thyroid antibodies before pregnancy are at higher risk.

Will postpartum thyroiditis go away?

For most women, yes. About 80% recover normal thyroid function within a year. About 20% develop permanent hypothyroidism needing lifelong treatment.

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