Subclinical hypothyroidism in pregnancy: an evolving and controversial landscape

This review aims to elucidate the developments in subclinical hypothyroidism (SCH) in pregnancy effects, management, and treatment. While mostly focusing on recent research, landmark studies are briefly reviewed to highlight major developments since their publication.

Research has continued to show an increased risk of adverse outcomes in pregnant women with SCH, with recent research showing an increased risk of both impaired glucose tolerance and hypertensive disorders of pregnancy. Research has continued to show unclear effects of SCH on neonatal outcomes, specifically in offsprings' intellectual development and ability. The benefit of treatment of SCH continues to be unclear; however, data suggest that treatment for thyroid stimulating hormone (TSH) 2.5-4 mU/l regardless of thyroid peroxidase antibodies status and TSH 4-10 mU/l in later pregnancy has not shown maternal or neonatal benefit.

With varying guidelines and inconsistent research outcomes, it is not surprising that SCH practices differ widely. Further research, with uniform definitions and criteria of SCH, is needed to elucidate the optimal management and treatment of this common pregnancy condition. Additionally, further research specifically aimed at optimizing TSH in preconception and early pregnancy is needed.