New ATA Guidelines Redefine Thyroid Care in Pregnancy | The Medical Education Network

Metabolic & Endocrine Disorders| Review | Thyroid Disorders | Obstetrics & Gynaecology

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Review | Thyroid Updates 2025 | Obstetrics & Gynaecology

New American Thyroid Association Guidelines Redefine Thyroid Care in Pregnancy

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Time to listen: 07:19

Published on MedED: 15 April 2025
Type of article: Review
MedED Catalogue Reference: MMERD003
Category: Metabolic & Endocrine Disorders
Cross Reference: Obstetrics & Gynaecology
Keywords: Obstetrics & Gynaecology

Key Takeaways

1. Routine levothyroxine is no longer recommended for euthyroid, TPO-positive women who are trying to conceive

2. Subclinical hypothyroidism should be confirmed with repeat testing, and treatment options should be considered in relation to the trimester

3. While propylthiouracil (PTU) remains the preferred antithyroid drug for Hyperthyroidic patients in early pregnancy due to lower teratogenic risk, the decision to start, continue, or stop medication should involve the patient.

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Thyroid disorders are among the most common endocrine conditions affecting women of reproductive age. Appropriate diagnosis and treatment during pregnancy are essential, as both overtreatment and undertreatment carry potential risks for maternal and foetal outcomes.

The American Thyroid Association (ATA) last updated its guidelines on managing thyroid disease in pregnancy in 2017.

Since then, significant new research has prompted a comprehensive revision. The new guidelines—due for release in early 2025—reflect a more nuanced, evidence-based approach, with a strong emphasis on individualised care, risk stratification, and patient-provider shared decision-making.

Note: The SEMDSA/ACE-SA Guideline for the Management of Hypothyroidism in Adults, published in 2015, does not have specific guidelines for the management of thyroid disease in pregnant women.

The new ATA guidelines had not been published at the time of this review, and the summary below has been compiled from congress documents. Furthermore, the SEMDSA/ACE-SA Guidelines remain the de facto guidelines for the treatment of hypothyroidism patients in South Africa, and this summary in no way replaces, amends or is a substitute for the SEMDSA Guidelines.

A high-level summary of the amendments

The revised recommendations cover preconception care, subclinical and overt thyroid dysfunction during pregnancy, and the management of thyroid nodules and cancer.

A Summary of Key changes include:

Preconception care

The updated guidelines recommend that women who are euthyroid but have TPO antibodies—previously considered candidates for preventive levothyroxine—should no longer be routinely treated. While TPO positivity is associated with an increased risk of thyroid dysfunction, a number of recent trials have shown no benefit from early levothyroxine in these patients.

Testing during pregnancy in this group also remains advised. For preconception subclinical hypothyroidism, the guidelines reinforce the importance of reassessing thyroid function, with treatment using low-dose levothyroxine if the condition persists.

In TPO antibody–positive patients, the guidelines recommend TSH levels be tested every 3–6 months until pregnancy.

Reassessment of risk factors

In the previous guidelines, risk factors that warranted thyroid testing included patients aged over 30, morbid obesity (BMI ≥ 40), and high parity.

These have now been removed as risk factors based on new evidence showing poor predictive value. Instead, testing should be guided by clinical symptoms, past thyroid dysfunction, or the presence of thyroid antibodies.

Risk factors prompting thyroid testing at presentation include a history of subclinical or clinical thyroid dysfunction, postpartum thyroiditis, thyroid antibody positivity, symptoms of thyroid disease, goitre, and other relevant clinical indicators.

Management of subclinical hypothyroidism

A major change is the decoupling of TPO antibody status from treatment decisions.

The timing of diagnosis now plays a central role:

In the first trimester, levothyroxine may be initiated for subclinical hypothyroidism (TSH above the upper limit of pregnancy-specific reference ranges).
Treatment is generally not recommended for TSH levels under 10 mU/L in the second and third trimesters due to the minimal associated risk.

Nonetheless, it is important to apply the guidelines with consideration for the individual patient, particularly when managing borderline TSH levels.

Re-testing before treatment

The ATA now recommends repeat thyroid testing within three weeks before confirming a diagnosis or initiating treatment for subclinical or mild overt hypothyroidism in early pregnancy.

This approach reflects new evidence showing that many patients spontaneously normalise their TSH levels, especially by the third trimester. The guidelines recommend that physicians discuss the available options with the patients before retesting or starting low-dose levothyroxine.

Overt hypothyroidism

TSH values ≥10 mU/L remain a clear threshold for treatment, regardless of trimester, with levothyroxine strongly recommended to prevent maternal and foetal complications.

Hyperthyroidism and Graves’ disease

For patients with overt hyperthyroidism, particularly Graves’ disease, the guidelines place greater emphasis on patient engagement.

While propylthiouracil (PTU) remains the preferred antithyroid drug in early pregnancy due to lower teratogenic risk, the decision to start, continue, or stop medication should involve the patient.

The guidelines suggest considering discontinuation of antithyroid medications upon a positive pregnancy test, which may be considered under close monitoring, except in high-risk patients.

Relapse typically does not occur until around 12 weeks after the passing of the high-risk teratogenic period (weeks 5–15).

For high-risk hyperthyroid patients, current recommendations to continue treatment remain unchanged.

Thyroid nodules and cancer

No major changes were made in this section. Most nodules can be monitored without intervention during pregnancy, and treatment for thyroid cancer is typically deferred until postpartum unless there is evidence of rapid growth or local invasion.

In Conclusion

These forthcoming ATA guidelines represent a shift toward more personalised, less interventional care for pregnant women with thyroid dysfunction.

By removing outdated risk markers, discouraging routine treatment of euthyroid TPO-positive individuals, and recognising the self-limiting nature of many mild thyroid abnormalities during pregnancy, the guidelines aim to reduce overtreatment.

Shared decision-making features prominently, particularly in the management of hyperthyroidism, where the benefits and risks of medication must be balanced on a case-by-case basis. Additionally, the introduction of simplified presentation formats and visual aids is expected to improve uptake and application in clinical practice.

Overall, the new guidance underscores a move away from blanket treatment strategies and towards tailored care that reflects the dynamic nature of thyroid physiology during pregnancy.

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References

1 Osinga, J. A. J., Liu, Y., Männistö, T., et al (2024). Risk Factors for Thyroid Dysfunction in Pregnancy: An Individual Participant Data Meta-Analysis. Thyroid : official journal of the American Thyroid Association, 34(5), 646–658. https://doi.org/10.1089/thy.2023.0646

2. Dave, J., Klisiewicz, A., Bayat, Z., Ahmed Mohamed, N., Stevens, Z., & Kinvig, T. (2015). SEMDSA/ACE-SA Guideline for the Management of Hypothyroidism in Adults. South African Family Practice, 57(6), 7. doi:https://doi.org/10.4102/safp.v57i6.4399

Additional Source Material

8 November 2024 | Medscape| Conferences Updates| Update Coming for Thyroid Disease in Pregnancy Guidelines Retrieved 8 April 2025. https://www.medscape.com/viewarticle/update-coming-thyroid-disease-pregnancy-guidelines-2024a1000kfm

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