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Just published May 31st, 2026, the American Thyroid Association’s newest guideline update on Thyroid Disease in Preconception, Pregnancy, and Postpartum.

The updated guidelines include recommendations on thyroid function testing, iodine supplementation, thyroid autoimmunity, hypothyroidism, hypothyroxinemia, hyperthyroidism and Graves’ disease, thyroid nodules and cancer, and postpartum thyroid dysfunction for women with infertility, pregnant women, and women during postpartum and/or lactation.

In today’s rapid update, we’ll just be going over a summary of key changes that were added to this 2026 update. For the full guideline, make sure to check it out on guidelinecentral.com

Let’s get started. 

Starting with the section on Thyroid Physiology and Thyroid Function Testing

  • The guideline now discusses multiple testing options for the identification of (ab)normal thyroid hormone availability during pregnancy and outlines advantages and disadvantages of alternative testing methods that impact laboratory and trimester-specific free thyroxine (fT4) reference intervals. 
  • The guideline provides an update on risk factors for thyroid disease during pregnancy that can be used to support an indication for thyroid function testing during pregnancy, removed risk factors that had only limited potential to differentiate outcomes, and updated the definitions of the remaining previously used risk factors.

Next the section on Iodine

  • The guideline now places greater emphasis on the fact that there remains no valid biomarker for measuring long-term iodine status in an individual person and that risk factors for iodine deficiency on the individual-level should continue to be considered when applicable.

On to the section on Thyroid Dysfunction and Infertility

  • For women who are euthyroid but thyroperoxidase antibody (TPOAb) positive, levothyroxine (LT4) treatment should not be offered to women with infertility, those planning fertility treatment, or those with a history of recurrent miscarriages. Instead, thyroid function may be checked every 3–6 months preconception as there remains a 7–9% risk of developing overt or subclinical hypothyroidism before or during pregnancy. 
  • For subclinical hypothyroidism, diagnostic confirmation with repeat thyroid function testing may be considered before LT4 treatment, because many women with a single abnormal TSH will have a normal TSH upon retesting.

Moving on to the section on Hypothyroidism, Thyroid Autoimmunity, and Hypothyroxinemia
Preconception and In Pregnancy

  • TPOAb status is no longer used to guide LT4 treatment decision-making in women with subclinical hypothyroidism. 
  • Indication for, or consideration of, LT4 treatment should now be determined according to the timing of subclinical hypothyroidism diagnosis. 
  • The guideline emphasizes repeat thyroid function testing to verify that mild overt hypothyroidism or subclinical hypothyroidism is persistent. The absolute risk increase for adverse pregnancy or child outcomes is generally small for mild overt hypothyroidism and subclinical hypothyroidism. There is no established evidence of any harm related to a short delay in the start of LT4 treatment.

Next the section on Hyperthyroidism Preconception, In Pregnancy, and Postpartum

  • In the rare case of a pregnant patient who requires urgent thyroid surgery, this operation should be performed at the time required. While new anesthesia recommendations published since the previous iteration of these guidelines endorse that surgery requiring general anesthesia can be performed safely during any trimester, it is still best to proceed with such surgery in the second trimester if possible. First-trimester miscarriages may be incorrectly ascribed to surgery, and fetal monitoring is warranted during surgery in the third trimester when the fetus is postviability and there may be a risk of needing an urgent delivery. 
  • There is greater emphasis on the usefulness of serum TSH receptor antibodies (TRAb) and/or thyroid-stimulating immunoglobulin (TSI) titers in guiding when ATDs may be discontinued to provide the lowest chance of Graves’ disease relapse, which can be used in shared decision-making during preconception counseling.

Moving on to the section on Thyroid Nodules and Cancer Preconception, In Pregnancy, and Postpartum

  • Greater emphasis is placed on applying the same considerations in the management of thyroid cancer during pregnancy as one would make outside of pregnancy, particularly given that the vast majority of thyroid cancers are low-risk. 
  • In the rare case of a pregnant patient who requires urgent thyroid surgery, this operation should be performed at the time required. While new anesthesia recommendations published since the past iteration of these guidelines endorse that surgery requiring general anesthesia can be performed safely during any trimester, it is still best to proceed with such surgery in the second trimester if possible. First-trimester miscarriage may be incorrectly attributed to surgery, and fetal monitoring is warranted during surgery in the third trimester when the fetus is postviability and there may be a risk of needing an urgent delivery. 
  • Recent guidelines from the United States and United Kingdom advise that lactating women who undergo surgery can begin breastfeeding as soon as they are awake enough to hold the baby, which is different from prior recommendations that advise the disposal of breastmilk for 24 hours after receiving anesthesia.

And last the section on Thyroid Dysfunction Postpartum

  • The guideline now places greater emphasis on shared decision-making and the role of the patient to be better informed on the signs, symptoms, and natural time course of postpartum thyroiditis. 
  • The guideline also provided greater detail regarding differences in the recommended durations of breastfeeding cessation related to radiopharmaceutical use in lactating women, should it be required for diagnostic or treatment purposes in Graves’ disease or differentiated thyroid cancers.

And there you have it. Make sure to check out the full guideline from the American Thyroid Association and other related clinical decision support tools at guidelinecentral.com.

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