CHICAGO — A preview of much-anticipated updates to guidelines on managing thyroid disease in pregnancy shows key changes to recommendations in the evolving field, ranging from consideration of the chance of spontaneous normalization of thyroid levels during pregnancy to a heightened emphasis on shared decision-making and the nuances can factor into personalized treatment.
The guidelines, expected to be published in early 2025, have not been updated since 2017, and with substantial advances and evidence from countless studies since then, the new guidelines were developed with a goal to start afresh, said ATA Thyroid and Pregnancy Guidelines Task Force cochair Tim IM Korevaar, MD, PhD, in presenting the final draft guidelines at the American Thyroid Association (ATA) 2024 Meeting.
“Obviously, we’re not going to ignore the 2017 guidelines, which have been a very good resource for us so far, but we really wanted to start from scratch and follow a ‘blank canvas’ approach in optimizing the evidence,” said Korevaar, an endocrinologist and obstetric internist with the Division of Pharmacology and Vascular Medicine & Academic Center for Thyroid Diseases, Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands.
The guidelines, developed through a collaborative effort involving a wide variety of related medical societies, involved 14 systematic literature reviews. While the pregnancy issues covered by the guidelines is extensive, key highlights include:
Management in Preconception
Beginning with preconception, a key change in the guidelines will be that patients with euthyroid thyroid peroxidase (TPO) antibodies, which can be indicative of thyroid dysfunction, routine treatment with levothyroxine is not recommended, based on new evidence from randomized trials of high-risk patients showing no clear benefit from the treatment.
“In these trials, and across analyses, there was absolutely no beneficial effect of levothyroxine in these patients [with euthyroid TPO antibody positivity],” he said.
With evidence showing, however, that TPO antibody positivity can lead to subclinical or overt hypothyroidism within 1 or 2 years, the guidelines will recommend that TPO antibody–positive patients do have thyroid stimulating hormone (TSH) levels tested every 3-6 months until pregnancy, and existing recommendations to test during pregnancy among those patients remain in place, Korevaar reported.
In terms of preconception subclinical hypothyroidism, the guidelines will emphasize the existing recommendation “to always strive to reassess” thyroid levels, and if subclinical hypothyroidism does persist, to treat with low-dose levothyroxine.
During Pregnancy
During pregnancy, the new proposed recommendations will reflect the important change that three key risk factors, including age over 30 years, having at least two prior pregnancies, and morbid obesity (body mass index [BMI] at least 40 kg/m2), previously considered a risk for thyroid dysfunction in pregnancy, should not, on their own, suggest the need for thyroid testing, based on low evidence of an increased risk in pregnancy.
Research on the issue includes a recent study from Korevaar’s team showing these factors to in fact have low predictability of thyroid dysfunction.
“We deemed that these risk differences weren’t really clinically meaningful (in predicting risk), and so we have removed to maternal age, BMI, and parity as risk factors for thyroid testing indications in pregnancy,” Korevaar said.
Factors considered a risk, resulting in recommended testing at presentation include a history of subclinical or clinical hypo- or hyperthyroidism, postpartum thyroiditis, known thyroid antibody positivity, symptoms of thyroid dysfunction or goiter, and other factors.