Subclinical hypothyroidism in early pregnancy associated with more than quadrupled risk of reduced thyroid function within 5 years of delivery

 A new study has shown that subclinical hypothyroidism diagnosed before 21 weeks of pregnancy is associated with more than fourfold higher rates of overt hypothyroidism or thyroid replacement therapy within 5 years of delivery. The study is published in the peer-reviewed journal Thyroid^®, the official journal of the American Thyroid Association^® (ATA^®).

Subclinical hypothyroidism, or a change in the levels of thyroid-stimulating hormone (TSH) that isn’t severe enough to cause symptoms, is especially common during pregnancy, affecting as many as 1 in 4 pregnant people. While subclinical hypothyroidism isn’t inherently dangerous, overt hypothyroidism comes with serious symptoms including fatigue, depression, and heart problems.

Michael Varner, MD, professor of obstetrics and gynecology in the Spencer Fox Eccles School of Medicine at University of Utah Health, and his coauthors reported that progression to overt hypothyroidism was more common in individuals with thyroid-stimulating hormone levels that were more than twice the normal level.

People with higher levels of antibodies against a thyroid enzyme, which can indicate that the body is mounting an autoimmune response against the thyroid, were also at higher risk of hypothyroidism within 5 years after delivery compared to those with lower levels of the antibody.

The investigators found that diagnosis of hypothyroxinemia, a deficiency in the thyroid hormone thyroxine, before 21 weeks of pregnancy was not associated with the development of overt hypothyroidism after delivery.

“Studying the long-term associations of test results, as well as the impacts of our interventions, during pregnancy on the health and well-being of mothers and children is a particularly important aspect of clinical research in perinatal medicine,” Varner says. “While the parent NICHD Maternal-Fetal Medicine Units Network trials from which our data are derived showed no difference in 5-year neurodevelopmental outcomes in children from prenatal treatment of either subclinical hypothyroidism or hypothyroxinemia, our data lend further evidence to the postpartum time period as a time when autoimmune diseases, in this case, hypothyroidism, are more likely to be present.”

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Press release originally published by Kathryn Ryan / Mary Ann Liebert, Inc.

About University of Utah Health

University of Utah Health  provides leading-edge and compassionate care for a referral area that encompasses Idaho, Wyoming, Montana, and much of Nevada. A hub for health sciences research and education in the region, U of U Health has a $522 million research enterprise and trains the majority of Utah’s physicians, and more than 1,670 scientists and 1,460 health care providers at its Colleges of Health, Nursing, and Pharmacy and Schools of Dentistry and Medicine. With more than 20,000 employees, the system includes 12 community clinics and five hospitals. U of U Health is recognized nationally as a transformative health care system and provider of world-class care.

About the Journal
Thyroid^®, the official journal of the American Thyroid Association^®, (ATA^®) is an authoritative peer-reviewed journal published monthly online with open access options and in print. Led by Editor-in-Chief Anna M. Sawka, MD, PhD, University of Toronto, the Journal publishes original articles and timely reviews that reflect the rapidly advancing changes in our understanding of thyroid physiology and pathology, from the molecular biology of the cell to clinical management of thyroid disorders. Complete tables of content and a sample issue may be viewed on the Thyroid website. The complete Thyroid Journal Program includes the highly valued abstract and commentary publication Clinical Thyroidology^®, led by Editor-in-Chief Trevor E. Angell, MD and published monthly, and the groundbreaking videojournal companion VideoEndocrinology, led by Editor Catherine F. Sinclair, MD, FRACS.      Complete tables of content and sample issues may be viewed on the Thyroid website.

About the American Thyroid Association®
The American Thyroid Association® (ATA) is dedicated to transforming thyroid care through clinical excellence, education, scientific discovery and advocacy in a collaborative and diverse community. ATA® is an international professional medical society with over 1,800 members from 43 countries around the world. The ATA® promotes thyroid awareness and information through Clinical Thyroidology® for the Public, a resource that summarizes research for patients and families, and extensive, authoritative resources on thyroid disease and thyroid cancer in both English and Spanish. The ATA® website www.thyroid.org serves as a bonafide clinical resource for patients and the public who look for reliable thyroid-related information. 

About the Publisher
Mary Ann Liebert, Inc. is a global media company dedicated to creating, curating, and delivering impactful peer-reviewed research and authoritative content services to advance the fields of biotechnology and the life sciences, specialized clinical medicine, and public health and policy. For complete information, please visit the Mary Ann Liebert, Inc. website.