Semin Reprod Med 2016; 34(06): 323-330
DOI: 10.1055/s-0036-1593488
Review Article
Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

Overview of Hypothyroidism in Pregnancy

Jeffrey M. Kroopnick
1  Division of Endocrinology, Diabetes and Metabolism, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
,
Caroline S. Kim
2  Division of Endocrinology, Diabetes and Metabolism, Corporal Michael J. Crescenz VA Medical Center and Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
› Author Affiliations
Further Information

Publication History

Publication Date:
14 October 2016 (online)

Abstract

Overt hypothyroidism in pregnancy, defined as an elevated serum thyroid-stimulating hormone (TSH) and reduced serum free thyroxine or a TSH >10 mIU/L, is known to have adverse effects on pregnancy. Subclinical hypothyroidism is typically defined as an elevated TSH and normal FT4 levels. There remains much controversy on the benefit of starting levothyroxine for mothers diagnosed with subclinical hypothyroidism. Recent studies are redefining the normal range for TSH in pregnancy, and the data on whether treatment of subclinical hypothyroidism improves outcomes for the mother and fetus are unclear. One confounding variable is the presence of thyroid peroxidase antibodies, as it may be a surrogate marker for other autoimmune disorders detrimental to pregnancy. If levothyroxine treatment is initiated, the dosing and monitoring strategy is different from nonpregnant individuals. Randomized clinical trials are underway that may better elucidate whether treatment of subclinical hypothyroidism is warranted.