The American Thyroid Association (ATA) just released an update to its 2017 guideline Thyroid Disease in Preconception, Pregnancy, and Postpartum based on new evidence surrounding gestational thyroid physiology, thyroid function tests, risks related to thyroid disease, and treatment options. The guideline represents current best practices on the care of women with thyroid disease before, during, and after pregnancy.
Below are summaries of what is new in each section of the 2026 guideline update. For the most thorough look at the following recommendations, along with their accompanying good practice statements, view the full-text version of the ATA guideline.
Key Updates from the 2026 ATA Thyroid Disease in Preconception, Pregnancy, and Postpartum Update
Thyroid Physiology and Thyroid Function Testing
The guideline now covers multiple testing options for identifying abnormal thyroid hormone availability during preganancy. The guideline outlines advantages and disadvantages of alternate testing methods that impact lab and trimester-specific free thyroxine reference intervals. The updated section also discusses risk factors that can be used to support an indication for thyroid function testing during pregnancy, and more.
Iodine
In this update, the ATA emphasized that there is no valid biomarker for measuring long-term iodine status in individuals. When applicable, risk factors for iodine deficiency should continue to be considered.
Thyroid Dysfunction and Infertility
The 2026 update notes that for women who are euthyroid but thyroperoxidase antibody positive, levothyroxine treatment should not be offered to women with infertility, women planning fertility treatment, or women with a history of recurrent miscarriages. Instead, thyroid function may be checked every three to six months preconception as there is a 7-9% risk of developing overt or subclinical hypothyroidism before or during pregnancy. Regarding subclinical hypothyroidism, diagnostic confirmation via repeated thyroid function testing may be an option prior to levothyroxine treatment.
Hypothyroidism, Thyroid Autoimmunity, and Hypothyroxinemia Preconception and in Pregnancy
The update states that thyroperoxidase antibody status is no longer used to guide levothyroxine treatment decision-making in women with subclinical hypothyroidism. Indication for or consideration of levothyroxine treatment should be determined according to the timing of subclinical hypothyroidism diagnosis. The guideline update emphasizes repeated thyroid function testing to verify mild overt hypothyroidism or subclinical hypothyroidism is persistent.
Hyperthyroidism Preconception, in Pregnancy, and Postpartum
The ATA recommends that in the event of a pregnant patient requiring urgent thyroid surgery, the operation be performed at the time required, in the second trimester if possible. Additionally, there is greater emphasis on the usefulness of serum thyrotropin receptor antibodies in guiding when antithyroid drugs may be discontinued for the lowest opportunity of Graves’ disease relapse.
Thyroid Nodules and Cancer Preconception, in Pregnancy, and Postpartum
The ATA guideline recommends applying the same considerations in managing thyroid cancer during pregnancy as would be made outside of pregnancy since most thyroid cancers are low-risk. The ATA recommends that in the event of a pregnant patient requiring urgent thyroid surgery, the operation be performed at the time required, in the second trimester if possible.
Thyroid Dysfunction Postpartum
ATA emphasized shared decision-making and for the patient to be better informed regarding the symptoms, signs, and natural time course of postpartum thyroiditis. The update provides more detail on the differences in recommended durations of breastfeeding cessation tied to radiopharmaceutical use in lactating mothers, if necessary for treatment or diagnostic purposes in Graves’ disease or differentiated thyroid cancers.
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